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V'.‘ ‘F. IE X E I TEXAS INSTRUMENTS
1
2
5
43
VIN SW
FB
EN
GND
L1: 2.2 PHVOUT
COUT: 10 PF
CIN: 4.7 PFLM3674-
ADJ
VIN
2.7V to 5.5V
C1
C2
R1
R2
1
2
5
4
3
VIN SW
FB
EN
GND
L1:2.2 PHVOUT
COUT
10 PF
CIN
4.7 PFLM3674
VIN
2.7V to 5.5V
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LM3674
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LM3674 2-MHz, 600-mA Step-Down DC-DC Converter in SOT-23
1 Features 3 Description
The LM3674 step-down DC-DC converter is
1 Input Voltage Range From 2.7 V to 5.5 V optimized for powering low-voltage circuits from a
600-mA Maximum Load Current single Li-Ion cell battery and input voltage rails from
Available in Fixed and Adjustable Output Voltages 2.7 V to 5.5 V. It provides up to 600-mA load current
Ranging From 1 V to 3.3 V over the entire input voltage range. There are several
fixed output voltages and adjustable output voltage
Operates From a Single Li-Ion Cell Battery versions.
Internal Synchronous Rectification for High The device offers superior features and performance
Efficiency for mobile phones and similar portable systems.
Internal Soft-Start During the Pulse Width Modulation (PWM) mode, the
0.01-µA Typical Shutdown Current device operates at a fixed-frequency of 2 MHz
2-MHz PWM Fixed Switching Frequency (typical) (typical). Internal synchronous rectification provides
high efficiency during the PWM mode operation. In
Current Overload Protection and Thermal shutdown mode, the device turns off and reduces
Shutdown Protection battery consumption to 0.01 µA (typical).
2 Applications The LM3674 is available in a 5-pin SOT-23 package.
A high switching frequency of 2 MHz (typical) allows
Mobile Phones use of only three tiny external surface-mount
• PDAs components, an inductor and two ceramic capacitors.
MP3 Players Device Information(1)
Portable Instruments PART NUMBER PACKAGE BODY SIZE (NOM)
• W-LAN LM3674 SOT-23 (5) 2.90 mm × 1.60 mm
Digital Still Cameras (1) For all available packages, see the orderable addendum at
Portable Hard Disk Drives the end of the data sheet.
Typical Application Circuit Typical Application Circuit for Adjustable Voltage
Option
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
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SNVS405G –DECEMBER 2005REVISED APRIL 2015
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Table of Contents
7.3 Feature Description................................................. 10
1 Features.................................................................. 17.4 Device Functional Modes........................................ 11
2 Applications ........................................................... 18 Application and Implementation ........................ 12
3 Description ............................................................. 18.1 Application Information............................................ 12
4 Revision History..................................................... 28.2 Typical Applications ................................................ 12
5 Pin Configuration and Functions......................... 39 Power Supply Recommendations...................... 17
6 Specifications......................................................... 410 Layout................................................................... 17
6.1 Absolute Maximum Ratings ...................................... 410.1 Layout Guidelines ................................................. 17
6.2 ESD Ratings.............................................................. 410.2 Layout Example .................................................... 18
6.3 Recommended Operating Conditions....................... 411 Device and Documentation Support ................. 19
6.4 Thermal Information.................................................. 411.1 Device Support...................................................... 19
6.5 Dissipation Ratings ................................................... 411.2 Trademarks........................................................... 19
6.6 Electrical Characteristics .......................................... 511.3 Electrostatic Discharge Caution............................ 19
6.7 Typical Characteristics.............................................. 611.4 Glossary................................................................ 19
7 Detailed Description.............................................. 912 Mechanical, Packaging, and Orderable
7.1 Overview ................................................................... 9Information ........................................................... 19
7.2 Functional Block Diagram......................................... 9
4 Revision History
Changes from Revision F (May 2013) to Revision G Page
Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional
Modes,Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1
Deleted "in leaded (Pb) and lead-free (no Pb) versions" ....................................................................................................... 1
Changes from Revision E (April 2013) to Revision F Page
Changed layout of National Data Sheet to TI format ........................................................................................................... 18
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VIN
1
GND
2
EN
3
FB
4
SW
5
LM3674
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SNVS405G –DECEMBER 2005REVISED APRIL 2015
5 Pin Configuration and Functions
DBV Package
5-Pin SOT-23
Top View
Note: The actual physical placement of the package marking will vary from part to part.
Pin Functions
PIN TYPE DESCRIPTION
NAME NUMBER
Enable input. The device is in shutdown mode when voltage to this pin is < 0.4 V and enable when > 1
EN 3 Digital V. Do not leave this pin floating.
Feedback analog input. Connect to the output filter capacitor, COUT, for fixed voltage versions. For
FB 4 Analog adjustable version, external resistor dividers are required (R1and R2). The internal resistor dividers are
disabled for the adjustable version.
GND 2 Ground Ground pin
SW 5 Analog Switching node connection to the internal PFET switch and NFET synchronous rectifier.
VIN 1 Power Power supply input. Connect to the input filter capacitor, CIN.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
VIN pin: voltage to GND 0.2 6 V
EN, FB, and SW pins GND 0.2 VIN + 0.2 V
Continuous power dissipation(3) Internally Limited
Junction temperature (TJ-MAX) 125 °C
Maximum lead temperature (soldering, 10 seconds) 260 °C
Storage temperature, Tstg –65 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) If Military- or Aerospace-specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications.
(3) In applications where high power dissipation and/or poor package resistance is present, the maximum ambient temperature may have to
be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX), the
maximum power dissipation of the device in the application (PD-MAX) and the junction-to-ambient thermal resistance of the package
(RθJA) in the application, as given by the following equation: TA-MAX = TJ-MAX – (RθJA × PD-MAX). See Dissipation Ratings for PD-MAX
values at different ambient temperatures.
6.2 ESD Ratings
VALUE UNIT
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) ±2000 V
Electrostatic
V(ESD) discharge Charged device model (CDM), per JEDEC specification JESD22-C101, all pins(2) ±200 V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)(1)
MIN MAX UNIT
Input voltage(2) 2.7 5.5 V
Recommended load current 0 600 mA
Junction temperature, TJ–30 125 °C
Ambient temperature,TA–30 85 °C
(1) All voltages are with respect to the potential at the GND pin.
(2) Input voltage range recommended for ideal applications performance for the specified output voltages are given below:
VIN = 2.7 V to 5.5 V for 1 V VOUT < 1.8 V
VIN = (VOUT + VDROP OUT) to 5.5 V for 1.8 VOUT 3.3 V, where VDROP OUT = ILOAD × (RDSON (P) + RINDUCTOR)
6.4 Thermal Information
LM3674
THERMAL METRIC(1) DBV (SOT-23) UNIT
5 PINS
4-layer board 130
RθJA Junction-to-ambient thermal resistance °C/W
2-layer board 250
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
6.5 Dissipation Ratings
over operating free-air temperature range (unless otherwise noted)
RθJA TA25°C (POWER RATING) TA= 60°C (POWER RATING) TA= 85°C (POWER RATING)
250°C/W (2-layer board) 400 mW 260 mW 160 mW
130°C/W (4-layer board) 770 mW 500 mW 310 mW
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6.6 Electrical Characteristics
Typical limits are TA= 25°C; unless otherwise noted, specifications apply to the LM3674 with VIN = EN = 3.6 V(1)(2)(3)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Feedback voltage(4)(5) IO= 10 mA, 30°C TJ125°C –4% 4%
VFB Line regulation 2.7 V VIN 5.5 V, IO= 100 mA 0.083 %/V
Load regulation 100 mA IO600 mA, VIN = 3.6 V 0.0010 %/mA
VREF Internal reference voltage See(6) 0.5 V
EN = 0 V 0.01
ISHDN Shutdown supply current µA
EN = 0 V, –30°C TJ125°C 1
No load, device is not switching (FB = 0 V) 300
IQDC bias current into VIN µA
No load, device is not switching (FB = 0 V) 600
–30°C TJ125°C
RDSON (P) Pin-to-pin resistance for PFET ISW = 200 mA 380 500 m
RDSON (N) Pin-to-pin resistance for NFET ISW = 200 mA 250 400 m
Open loop(7) 1020
ILIM Switch peak current limit mA
Open loop(7), –30°C TJ125°C 830 1200
VIH Logic high input –30°C TJ125°C 1 V
VIL Logic low input –30°C TJ125°C 0.4 V
0.01
IEN Enable (EN) input current µA
–30°C TJ125°C 1
PWM mode 2
FOSC Internal oscillator frequency MHz
PWM mode, 30°C TJ125°C 1.6 2.6
(1) All voltages are with respect to the potential at the GND pin.
(2) Minimum and maximum limits are specified by design, test, or statistical analysis. Typical numbers represent the most likely values.
(3) The parameters in the Electrical Characteristics are tested at VIN = 3.6 V unless otherwise specified. For performance curves over the
input voltage range, see Typical Characteristics.
(4) ADJ configured to 1.5-V output.
(5) For VOUT < 2.5 V, VIN = 3.6 V; for VOUT 2.5 V, VIN = VOUT + 1.
(6) For the ADJ version the resistor dividers should be selected such that at the desired output voltage, the voltage at the FB pin is 0.5 V.
(7) See Typical Characteristics for closed loop data and its variation with regards to supply voltage and temperature. Electrical
Characteristics reflect open loop data (FB = 0 V and current drawn from the SW pin ramped up until cycle-by-cycle current limit is
activated). Closed-loop current limit is the peak inductor current measured in the application circuit by increasing output current until
output voltage drops by 10%.
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l TEXAS INSTRUMENTS 420 0,40 i 400 F 350 z E 360 K TA : 25° c 8 ,_ 3A0 E g 32° TA : ‘90°C u: 3 300 G 250 TA = -3o°c 260 25 30 35 A0 45 so 55 so SUPPLV VOLTAGE (V) 0 1 52 I [ vow = 1 5v g E 1 51 V 0 E g IOUT 00 mA m J m g 1 so 3 F 0 :1 w :L g ’5 m o 149 CW: 00 mA— 1 4e 730 u 30 so 90 120 25 so 35 40 45 50 55 so TEMPERATURE (°C) SUPPLY VOLTAGE (V) 1 52 1 54 \4N : 3 av 15: Vow: ‘ 5V V1N=36V A A v ' = 1'5v Z 7 00 A E OUY $150 IOWA m 0152 5 75 O 5 > 1 49 > 5 I0 : 600 mA 'ow = M E \\ l m g \\ S 148 >— 1 SD 0 3 1 47 1 4s 1 4B 730 o 30 so 90 o 100 200 300 400 soo soo TEMPERATURE (°C) OUTPUT CURRENT (mA)
-10 10 30 50 70 90
TEMPERATURE (°C)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
SHUTDOWN CURRENT (PA)
-30
EN = GND
VIN = 3.6V
VIN = 2.7V
VIN = 5.5V
LM3674
SNVS405G –DECEMBER 2005REVISED APRIL 2015
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6.7 Typical Characteristics
(unless otherwise stated: VIN = 3.6 V, VOUT = 1.5 V, TA= 25°C)
FB = 0 V, No Switching
Figure 1. Quiescent Current vs Supply Voltage Figure 2. IQShutdown vs Temperature
Figure 3. Feedback Bias Current vs Temperature Figure 4. Output Voltage vs Supply Voltage
Figure 5. Output Voltage vs Temperature Figure 6. Output Voltage vs Output Current
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l TEXAS INSTRUMENTS sun 2m 30 2o 10 10 100 1000 OUTPUT CURRENT (mA) Ame. oco 100 100 so so so so $3 70 $3 70 > > g 60 g 60 U U 9 50 9 50 k k m 40 m 40 30 30 20 20 VIN=45V 10 10 10 100 1000 10 100 1000 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 100 100 vom=1av so so so V‘N: W 80 § 70 § 70 >- >- 3 so 3 so “.1 “.1 9 so 9 so u u b 40 b 40 10 100 1000 OUTPUT CURRENT (mA)
-10 10 30 50 70 90 110
TEMPERATURE (°C)
100
150
200
250
300
350
400
450
500
550
600
RDS(ON) (m:)
-30
NFET
VIN = 4.5V
PFET
VIN = 2.7V
VIN = 4.5V VIN = 3.6V
VIN = 3.6V
VIN = 2.7V
LM3674
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SNVS405G –DECEMBER 2005REVISED APRIL 2015
Typical Characteristics (continued)
(unless otherwise stated: VIN = 3.6 V, VOUT = 1.5 V, TA= 25°C)
Figure 7. RDSON vs Temperature Figure 8. Switching Frequency vs Temperature
VOUT = 1.2 V, L = 2.2 µH, DCR = 200 mVOUT = 1.5 V, L = 2.2 µH, DCR = 200 m
Figure 9. Efficiency vs Output Current Figure 10. Efficiency vs Output Current
VOUT = 1.8 V, L = 2.2 µH, DCR = 200 mVOUT = 3.3 V, L = 2.2 µH, DCR = 200 m
Figure 11. Efficiency vs Output Current Figure 12. Efficiency vs Output Current
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l TEXAS INSTRUMENTS CURRENT UMIT (mA) 1200 CLOSE LOOP I150 1100 1050 10““ v‘N = 3 av OPEN LOOP 950 900 -AU -2u 0 20 Au 6U 80 100 TEMPERATURE (”C) Vow 20 mv/DIV AC Coupled 3.6V VIN 3.0V vow : 1.5V lou-r = 400 mA 40 ys/DIV 2V/DIV 20 mV/DIV AC Coupled 400 mA 200 mA \iw '3.sv Vaut = 1.5V sz w 5V/DIV fl 1V/DIV ‘ 5v zuu mA/DIV Vow ”ff EN 2V/DIV 40 ps/DIV 20 psiDlV ZV/DIV mow zoo mA/DIV ZV/DIV 40 us/DIV
LM3674
SNVS405G –DECEMBER 2005REVISED APRIL 2015
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Typical Characteristics (continued)
(unless otherwise stated: VIN = 3.6 V, VOUT = 1.5 V, TA= 25°C)
Figure 14. Line Transient Response
Figure 13. Open or Closed Loop Current Limit vs
Temperature
Output Current = 300 mA
Figure 16. Start-Up
Figure 15. Load Transient
Output Current = 10 mA
Figure 17. Start-Up
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‘Nv ""'"""""""""""I' 5 Errov Amp
+
-
2 MHz
Oscillator
Soft
Start
Ramp
Generator
+
-
Thermal
Shutdown
Undervoltage
Lockout
VREF +
-
0.5V
Error
Amp Control Logic Driver
Current Limit
Comparator
Ref1
SW
FB
EN VIN
PWM Comparator
GND
Bandgap
+
-
Vcomp
1.0V
Frequency
Compensation
Adjustable Version
Fixed Version
LM3674
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SNVS405G –DECEMBER 2005REVISED APRIL 2015
7 Detailed Description
7.1 Overview
The LM3674, a high-efficiency, step-down, DC-DC switching buck converter, delivers a constant voltage from a
single Li-Ion battery and input voltage rails from 2.7 V to 5.5 V to portable devices such as cell phones and
PDAs. Using a voltage mode architecture with synchronous rectification, the LM3674 has the ability to deliver up
to 600 mA depending on the input voltage, output voltage, ambient temperature, and the inductor chosen.
Additional features include soft-start, undervoltage protection, current overload protection, and thermal overload
protection. As shown in Typical Application Circuit, only three external power components, CIN, COUT, and L1, are
required for implementation.
The part uses an internal reference voltage of 0.5 V. It is recommended to keep the part in shutdown mode until
the input voltage is 2.7 V or higher.
7.2 Functional Block Diagram
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VOUT
TIME (200 ns/DIV)
200 mA/DIV
IL
VSW 2V/DIV
10 mV/DIV
AC Coupled
VIN = 3.6V
VOUT = 1.5V IOUT = 400 mA
-VOUT
L
VIN-VOUT
L
LM3674
SNVS405G –DECEMBER 2005REVISED APRIL 2015
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7.3 Feature Description
7.3.1 Circuit Operation
During the first portion of each switching cycle, the control block in the LM3674 turns on the internal PFET
switch. This allows current to flow from the input through the inductor to the output filter capacitor and load. The
inductor limits the current to a ramp with a slope of:
(1)
by storing energy in a magnetic field. During the second portion of each cycle, the controller turns the PFET
switch off, blocking current flow from the input, and then turns the NFET synchronous rectifier on. The inductor
draws current from ground through the NFET to the output filter capacitor and load, which ramps the inductor
current down with a slope of:
(2)
The output filter stores charge when the inductor current is high, and releases it when the inductor current is low,
smoothing the voltage across the load.
The output voltage is regulated by modulating the PFET switch-on time to control the average current sent to the
load. The effect is identical to sending a duty-cycle modulated rectangular wave formed by the switch and
synchronous rectifier at the SW pin to a low-pass filter formed by the inductor and output filter capacitor. The
output voltage is equal to the average voltage at the SW pin.
7.3.2 PWM Operation
During PWM operation, the converter operates as a voltage-mode controller with input voltage feed-forward. This
allows the converter to achieve excellent load and line regulation. The DC gain of the power stage is proportional
to the input voltage. To eliminate this dependence, feed-forward inversely proportional to the input voltage is
introduced.
While in PWM mode, the output voltage is regulated by switching at a constant frequency and then modulating
the energy per cycle to control power to the load. At the beginning of each clock cycle, the PFET switch is turned
on and the inductor current ramps up until the comparator trips and the control logic turns off the switch.
The current limit comparator can also turn off the switch in case the current limit of the PFET is exceeded. Then
the NFET switch is turned on and the inductor current ramps down. The next cycle is initiated by the clock
turning off the NFET and turning on the PFET.
Figure 18. PWM Operation
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Feature Description (continued)
7.3.2.1 Internal Synchronous Rectification
While in PWM mode, the LM3674 uses an internal NFET as a synchronous rectifier to reduce rectifier forward
voltage drop and associated power loss. Synchronous rectification provides a significant improvement in
efficiency whenever the output voltage is relatively low compared to the voltage drop across an ordinary rectifier
diode.
7.3.2.2 Current Limiting
A current limit feature allows the LM3674 to protect itself and external components during overload conditions.
PWM mode implements current limiting using an internal comparator that trips at 1020 mA (typical). If the output
is shorted to ground, then the device enters a timed current-limit mode where the NFET is turned on for a longer
duration until the inductor current falls below a low threshold, ensuring inductor current has more time to decay,
and thereby preventing runaway.
7.4 Device Functional Modes
There are two modes of operation depending on the current required: Pulse Width Modulation (PWM) and
shutdown. The device operates in PWM mode throughout the IOUT range. Shutdown mode turns off the device,
offering the lowest current consumption (ISHUTDOWN = 0.01 µA, typical). Additional features include soft-start,
undervoltage protection, and current overload protection.
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l TEXAS INSTRUMENTS WT”.
1
2
5
4
3
VIN SW
FB
EN
GND
L1:2.2 PHVOUT
COUT
10 PF
CIN
4.7 PFLM3674
VIN
2.7V to 5.5V
LM3674
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Soft-Start
The LM3674 has a soft-start circuit that limits in-rush current during start-up. During start-up the switch current
limit is increased in steps. Soft-start is activated only if EN goes from logic low to logic high after VIN reaches 2.7
V. Soft-start is implemented by increasing switch current limit in steps of 70 mA, 140 mA, 280 mA, and 1020 mA
(typical switch current limit). The start-up time thereby depends on the output capacitor and load current
demanded at start-up. Typical start-up times with 10-µF output capacitor and a 300-mA load current is 350 µs
and with a 10-mA load current is 240 µs.
8.1.2 Low-Dropout (LDO) Operation
The LM3674-ADJ can operate at 100% duty-cycle (no switching, PMOS switch completely on) for low-dropout
support of the output voltage. In this way the output voltage will be controlled down to the lowest possible input
voltage. When the device operates near 100% duty-cycle, the output voltage supply ripple is slightly higher,
approximately 25 mV.
The minimum input voltage needed to support the output voltage is:
VIN,MIN = ILOAD × (RDSON (P) + RINDUCTOR)+VOUT
where:
• ILOAD is load current
• RDSON (P) is drain-to-source resistance of PFET switch in the triode region
• RINDUCTOR is inductor resistance (3)
8.2 Typical Applications
8.2.1 Typical Application for Fixed Voltage Configuration
Figure 19. Fixed-Voltage Typical Application Circuit
8.2.1.1 Design Requirements
DESIGN PARAMETER EXAMPLE VALUE
Input voltage 3.6 V
Output voltage 1.5 V
Output current 300 mA
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l TEXAS INSTRUMENTS w 7&7] T)
where VIN - VOUT
2 x L
IRIPPLE = VOUT
VIN
1
f¹
·
©
§
¹
·
©
§
¹
·
©
§
IRIPPLE
IOUTMAX +ISAT >
LM3674
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8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Inductor Selection
There are two main considerations when choosing an inductor:
The inductor should not saturate.
The inductor current ripple should be small enough to achieve the desired output voltage ripple.
Different saturation current rating specifications are followed by different manufacturers so attention must be
given to details. Saturation current ratings are typically specified at 25°C. However, ratings at the maximum
ambient temperature of the application should be requested from the manufacturer. The minimum value of
inductance to ensure good performance is 1.76 µH at ILIM (typical) DC current over the ambient temperature
range. Shielded inductors radiate less noise and should be preferred.
There are two methods to choose the inductor saturation current rating:
Method 1:
The saturation current is greater than the sum of the maximum load current and the worst case average to peak
inductor current. This can be written as:
(4)
and
• IRIPPLE is average-to-peak inductor current
• IOUTMAX is maximum load current (600 mA)
• VIN is maximum input voltage in application
L is minimum inductor value including worst case tolerances (30% drop can be considered for method 1
f is minimum switching frequency (1.6 MHz)
• VOUT is output voltage (5)
Method 2:
A more conservative and recommended approach is to choose an inductor that has saturation current rating
greater than the maximum current limit of 1200 mA.
A 2.2-µH inductor with a saturation current rating of at least 1200 mA is recommended for most applications. The
resistance of the inductor should be less than 0.3 for good efficiency. Table 1 lists suggested inductors and
suppliers. For low-cost applications, an unshielded bobbin inductor is suggested. For noise critical applications, a
toroidal or shielded-bobbin inductor should be used. A good practice is to lay out the board with overlapping
footprints of both types for design flexibility. This allows substitution of a low-noise toroidal inductor in the event
that noise from low-cost bobbin models is unacceptable.
Table 1. Suggested Inductors and Their Suppliers
MODEL VENDOR DIMENSIONS L×W×H (mm) D.C.R (maximum) (m)
DO3314-222MX Coilcraft 3.3 x 3.3 x 1.4 200
LPO3310-222MX Coilcraft 3.3 x 3.3 x 1.0 150
ELL5GM2R2N Panasonic 5.2 x 5.2 x 1.5 53
CDRH2D14NP-2R2NC Sumida 3.2 x 3.2 x 1.55 94
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l TEXAS INSTRUMENTS ,: — V‘N OUT Vow a
VPP-RMS = VPP-C2 + VPP-ESR2
VOUT = VPP-ESR = IPP * RESR
VPP-C = Iripple
f x 4 x C
IRMS OUTMAX x x (1 - VOUT
VIN
VOUT
VIN
= I
=
r)
+12
2
The worst case is when
OUT
V
VIN
( ) OUT
V
VIN
r-x
Lf
x x x VIN = 2 x OUT
V
OUTMAX
I
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SNVS405G –DECEMBER 2005REVISED APRIL 2015
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8.2.1.2.2 Input Capacitor Selection
A ceramic input capacitor of 4.7 µF, 6.3 V is sufficient for most applications. Place the input capacitor as close as
possible to the VIN pin of the device. A larger value may be used for improved input voltage filtering. Use X7R or
X5R types; do not use Y5V. DC bias characteristics of ceramic capacitors must be considered when selecting
case sizes like 0805 and 0603. The minimum input capacitance to ensure good performance is 2.2 µF at 3-V DC
bias; 1.5 µF at 5-V DC bias including tolerances and over ambient temperature range. The input filter capacitor
supplies current to the PFET switch of the LM3674 in the first half of each cycle and reduces voltage ripple
imposed on the input power source. The low equivalent series resistance (ESR) of a ceramic capacitor provides
the best noise filtering of the input voltage spikes due to this rapidly changing current. Select a capacitor with
sufficient ripple current rating. The input current ripple can be calculated as:
(6)
8.2.1.2.3 Output Capacitor Selection
A ceramic output capacitor of 10 µF, 6.3 V is sufficient for most applications. Use X7R or X5R types; do not use
Y5V. DC bias characteristics of ceramic capacitors must be considered when selecting case sizes like 0805 and
0603. DC-bias characteristics vary from manufacturer to manufacturer and DC-bias curves should be requested
from them as part of the capacitor selection process.
The minimum output capacitance to ensure good performance is 5.75 µF at 1.8 V DC bias including tolerances
and over ambient temperature range. The output filter capacitor smoothes out current flow from the inductor to
the load, helps maintain a steady output voltage during transient load changes, and reduces output voltage
ripple. These capacitors must be selected with sufficient capacitance and sufficiently low ESR to perform these
functions.
The output voltage ripple is caused by the charging and discharging of the output capacitor and by the RESR and
can be calculated as:
Voltage peak-to-peak ripple due to capacitance can be expressed as:
(7)
Voltage peak-to-peak ripple due to ESR:
(8)
Because these two components are out of phase, the root mean squared (rms) value can be used to get an
approximate value of peak-to-peak ripple.
Voltage peak-to-peak ripple, rms:
(9)
Note that the output ripple is dependent on the current ripple and the equivalent series resistance of the output
capacitor (RESR).
The RESR is frequency-dependent (as well as temperature-dependent); make sure the value used for calculations
is at the switching frequency of the part.
14 Submit Documentation Feedback Copyright © 2005–2015, Texas Instruments Incorporated
Product Folder Links: LM3674
l TEXAS INSTRUMENTS
1
2
5
43
VIN SW
FB
EN
GND
L1: 2.2 PHVOUT
COUT: 10 PF
CIN: 4.7 PFLM3674-
ADJ
VIN
2.7V to 5.5V
C1
C2
R1
R2
LM3674
www.ti.com
SNVS405G –DECEMBER 2005REVISED APRIL 2015
Table 2. Suggested Capacitors and Their Suppliers
MODEL TYPE VENDOR VOLTAGE RATING (V) CASE SIZE [Inch (mm)]
10 µF for COUT
GRM21BR60J106K Ceramic, X5R Murata 6.3 0805 (2012)
C2012X5R0J106K Ceramic, X5R TDK 6.3 0805 (2012)
JMK212BJ106K Ceramic, X5R Taiyo-Yuden 6.3 0805 (2012)
4.7 µF for CIN
GRM21BR60J475K Ceramic, X5R Murata 6.3 0805 (2012)
JMK212BJ475K Ceramic, X5R Taiyo-Yuden 6.3 0805 (2012)
C2012X5R0J475K Ceramic, X5R TDK 6.3 0805 (2012)
8.2.1.3 Application Curves
Table 3. Related Plots
PLOT TITLE FIGURE
Output Voltage vs Supply Voltage Figure 4
Output Voltage vs Temperature Figure 5
Output Voltage vs Output Current Figure 6
Efficiency vs Output Current Figure 9
Efficiency vs Output Current Figure 10
Efficiency vs Output Current Figure 11
Efficiency vs Output Current Figure 12
Line Transient Response Figure 14
Load Transient Figure 15
Start-Up Figure 16
Start-Up Figure 17
8.2.2 Typical Application Circuit for Adjustable Voltage Option
Figure 20. Typical Application Circuit for Adjustable Voltage Option Schematic
8.2.2.1 Design Requirements
DESIGN PARAMETER EXAMPLE VALUE
Output voltage 1.5 V
Copyright © 2005–2015, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Links: LM3674
l TEXAS INSTRUMENTS 7+1) R2
Fz = 1
(2 * S * R1 * C1)
Fp = 1
2 * S * (R1 R2) * (C1+C2)
C2 =1
2 x S x R2 x 45 kHz
C1 =1
2 x S x R1 x 45 kHz
VOUT = R1
R2
VFB * + 1
( )
LM3674
SNVS405G –DECEMBER 2005REVISED APRIL 2015
www.ti.com
8.2.2.2 Detailed Design Procedure
8.2.2.2.1 Output Voltage Selection for Adjustable (LM3674-ADJ)
The output voltage of the adjustable parts can be programmed through the resistor network connected from VOUT
to FB then to GND. VOUT will be adjusted to make FB equal to 0.5 V. The resistor from FB to GND (R2) should
be 200 kto keep the current drawn through this network small but large enough that it is not susceptible to
noise. If R2is 200 k, and given the VFB is 0.5 V, then the current through the resistor feedback network will be
2.5 µA. The output voltage formula is:
where:
• VOUT = Output voltage (V)
• VFB = Feedback voltage (0.5 V typical)
• R1= Resistor from VOUT to FB ()
• R2= Resistor from FB to GND () (10)
For any output voltage greater than or equal to 1.0 V, a frequency zero must be added at 45 kHz for stability.
The formula is:
(11)
For output voltages greater than or equal to 2.5 V, a pole must also be placed at 45 kHz as well. If the pole and
zero are at the same frequency the formula for calculation of C2 is:
(12)
The formula for location of zero and pole frequency created by adding C1,C2 are given below. It can be seen
that by adding C1, a zero as well as a higher frequency pole is introduced.
(13)
See Table 4.
Table 4. Adjustable LM3674 Configurations for Various VOUT
VOUT (V) R1 (k) R2 (k) C1 (pF) C2 (pF) L (µH) CIN (µF) COUT (µF)
1.0 200 200 18 None 2.2 4.7 10
1.1 191 158 18 None 2.2 4.7 10
1.2 280 200 12 None 2.2 4.7 10
1.5 357 178 10 None 2.2 4.7 10
1.6 442 200 8.2 None 2.2 4.7 10
1.7 432 178 8.2 None 2.2 4.7 10
1.8 464 178 8.2 None 2.2 4.7 10
1.875 523 191 6.8 None 2.2 4.7 10
2.5 402 100 8.2 None 2.2 4.7 10
2.8 464 100 8.2 33 2.2 4.7 10
3.3 562 100 6.8 33 2.2 4.7 10
16 Submit Documentation Feedback Copyright © 2005–2015, Texas Instruments Incorporated
Product Folder Links: LM3674
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LM3674
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SNVS405G –DECEMBER 2005REVISED APRIL 2015
8.2.2.3 Application Curves
Table 5. Related Plots
PLOT TITLE FIGURE
Output Voltage vs Supply Voltage Figure 4
Output Voltage vs Temperature Figure 5
Output Voltage vs Output Current Figure 6
Efficiency vs Output Current Figure 9
Efficiency vs Output Current Figure 10
Efficiency vs Output Current Figure 11
Efficiency vs Output Current Figure 12
Line Transient Response Figure 14
Load Transient Figure 15
Start-Up Figure 16
Start-Up Figure 17
9 Power Supply Recommendations
The LM3674 requires a single supply input voltage. This voltage can range between 2.7 V to 5.5 V and be able
to supply enough current for a given application.
10 Layout
10.1 Layout Guidelines
PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance
of a DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce, and resistive voltage loss
in the traces. These can send erroneous signals to the DC-DC converter device, resulting in poor regulation or
instability.
Good layout for the LM3674 can be implemented by following a few simple design rules, as illustrated in
Figure 21.
1. Place the LM3674, inductor and filter capacitors close together and make the traces short. The traces
between these components carry relatively high switching currents and act as antennas. Following this rule
reduces radiated noise. Special care must by given to place the input filter capacitor very close to the VIN and
GND pin.
2. Arrange the components so that the switching current loops curl in the same direction. During the first half of
each cycle, current flows from the input filter capacitor, through the LM3674 and inductor to the output filter
capacitor and back through ground, forming a current loop. In the second half of each cycle, current is pulled
up from ground, through the LM3674 by the inductor, to the output filter capacitor and then back through
ground, forming a second current loop. Routing these loops so the current curls in the same direction
prevents magnetic field reversal between the two half-cycles and reduces radiated noise.
3. Connect the ground pins of the LM3674, and filter capacitors together using generous component-side
copper fill as a pseudo-ground plane. Then, connect this to the ground-plane (if one is used) with several
vias. This reduces ground-plane noise by preventing the switching currents from circulating through the
ground plane. It also reduces ground bounce at the LM3674 by giving it a low-impedance ground connection.
4. Use wide traces between the power components and for power connections to the DC-DC converter circuit.
This reduces voltage errors caused by resistive losses across the traces.
5. Route noise sensitive traces, such as the voltage feedback path, away from noisy traces between the power
components. The voltage feedback trace must remain close to the LM3674 circuit and should be direct but
should be routed opposite to noisy components. This reduces the EMI radiated onto the voltage feedback
trace of the DC-DC converter. A good approach is to route the feedback trace on another layer and to have a
ground plane between the top layer and layer on which the feedback trace is routed. In the same manner for
the adjustable part it is desired to have the feedback dividers on the bottom layer.
6. Place noise sensitive circuitry, such as radio IF blocks, away from the DC-DC converter, CMOS digital blocks
Copyright © 2005–2015, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: LM3674
I TFJms INSTRUMENTS
LM3674
SNVS405G –DECEMBER 2005REVISED APRIL 2015
www.ti.com
Layout Guidelines (continued)
and other noisy circuitry. Interference with noise-sensitive circuitry in the system can be reduced through
distance.
In mobile phones, for example, a common practice is to place the DC-DC converter on one corner of the board,
arrange the CMOS digital circuitry around it (because this also generates noise), and then place sensitive
preamplifiers and IF stages on the diagonally opposing corner. Often, the sensitive circuitry is shielded with a
metal pan and power to it is post-regulated to reduce conducted noise by using low-dropout linear regulators.
10.2 Layout Example
Figure 21. Board Layout Design Rules for the LM3674
18 Submit Documentation Feedback Copyright © 2005–2015, Texas Instruments Incorporated
Product Folder Links: LM3674
l TEXAS INSTRUMENTS
LM3674
www.ti.com
SNVS405G –DECEMBER 2005REVISED APRIL 2015
11 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.2 Trademarks
All trademarks are the property of their respective owners.
11.3 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.4 Glossary
SLYZ022 TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
Copyright © 2005–2015, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Links: LM3674
I TEXAS INSTRUMENTS Samples Samples Samples Samples Samples Sample: Sample: Samples Samples Samples Samples
PACKAGE OPTION ADDENDUM
www.ti.com 30-Sep-2021
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM3674MF-1.2/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLRB
LM3674MF-1.5/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLSB
LM3674MF-1.8/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLHB
LM3674MF-1.875/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SNNB
LM3674MF-2.8/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLZB
LM3674MF-ADJ NRND SOT-23 DBV 5 1000 Non-RoHS
& Green Call TI Level-1-260C-UNLIM -30 to 85 SLTB
LM3674MF-ADJ/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLTB
LM3674MFX-1.2/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLRB
LM3674MFX-1.5/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLSB
LM3674MFX-1.8/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLHB
LM3674MFX-1.875/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SNNB
LM3674MFX-ADJ/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -30 to 85 SLTB
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
I TEXAS INSTRUMENTS
PACKAGE OPTION ADDENDUM
www.ti.com 30-Sep-2021
Addendum-Page 2
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
l TEXAS INSTRUMENTS REEL DIMENSIONS TAPE DIMENSIONS 7 “K0 '«Pt» Reel Dlameter A0 Dimension designed to accommodate the component Width ED Dimension designed to accommodate the component tengtn K0 Dimension designed to accommodate the component thickness 7 w Overau Width onhe carrier tape i P1 Pitch between successive cavtty centers f T Reel Width (W1) QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE C) O O D O O D O SprocketHotes ,,,,,,,,,,, ‘ User Dtrecllon 0' Feed Pockel Quadrants
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LM3674MF-1.2/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MF-1.5/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MF-1.8/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MF-1.875/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MF-2.8/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MF-ADJ SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MF-ADJ/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MFX-1.2/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MFX-1.5/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MFX-1.8/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MFX-1.875/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM3674MFX-ADJ/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
PACKAGE MATERIALS INFORMATION
www.ti.com 21-Oct-2021
Pack Materials-Page 1
l TEXAS INSTRUMENTS TAPE AND REEL BOX DIMENSIONS
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM3674MF-1.2/NOPB SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MF-1.5/NOPB SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MF-1.8/NOPB SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MF-1.875/NOPB SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MF-2.8/NOPB SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MF-ADJ SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MF-ADJ/NOPB SOT-23 DBV 5 1000 208.0 191.0 35.0
LM3674MFX-1.2/NOPB SOT-23 DBV 5 3000 208.0 191.0 35.0
LM3674MFX-1.5/NOPB SOT-23 DBV 5 3000 208.0 191.0 35.0
LM3674MFX-1.8/NOPB SOT-23 DBV 5 3000 208.0 191.0 35.0
LM3674MFX-1.875/NOPB SOT-23 DBV 5 3000 208.0 191.0 35.0
LM3674MFX-ADJ/NOPB SOT-23 DBV 5 3000 208.0 191.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 21-Oct-2021
Pack Materials-Page 2
www.ti.com
PACKAGE OUTLINE
C
0.22
0.08 TYP
0.25
3.0
2.6
2X 0.95
1.9
1.45
0.90
0.15
0.00 TYP
5X 0.5
0.3
0.6
0.3 TYP
8
0 TYP
1.9
A
3.05
2.75
B
1.75
1.45
(1.1)
SOT-23 - 1.45 mm max heightDBV0005A
SMALL OUTLINE TRANSISTOR
4214839/F 06/2021
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. Refernce JEDEC MO-178.
4. Body dimensions do not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.25 mm per side.
0.2 C A B
1
34
5
2
INDEX AREA
PIN 1
GAGE PLANE
SEATING PLANE
0.1 C
SCALE 4.000
www.ti.com
EXAMPLE BOARD LAYOUT
0.07 MAX
ARROUND 0.07 MIN
ARROUND
5X (1.1)
5X (0.6)
(2.6)
(1.9)
2X (0.95)
(R0.05) TYP
4214839/F 06/2021
SOT-23 - 1.45 mm max heightDBV0005A
SMALL OUTLINE TRANSISTOR
NOTES: (continued)
5. Publication IPC-7351 may have alternate designs.
6. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
SYMM
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:15X
PKG
1
34
5
2
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
SOLDER MASK
DEFINED
EXPOSED METAL
METAL
SOLDER MASK
OPENING
NON SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
EXPOSED METAL
www.ti.com
EXAMPLE STENCIL DESIGN
(2.6)
(1.9)
2X(0.95)
5X (1.1)
5X (0.6)
(R0.05) TYP
SOT-23 - 1.45 mm max heightDBV0005A
SMALL OUTLINE TRANSISTOR
4214839/F 06/2021
NOTES: (continued)
7. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
8. Board assembly site may have different recommendations for stencil design.
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
SCALE:15X
SYMM
PKG
1
34
5
2
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