PMP7993.2: ±5 @ 100mA, ±15V @ 50mA, 7 ~ 32V in


This Flybuck reference design uses the LM5017 buck regulator to generate four isolated outputs: ±15V@50mA and ±5V@100mA. The regulation is done on the primary side, and thus no opto-coupler is needed. The overall load/line regulation for each output is within +/-5%. The input voltage range is from 17V to 32V. It's suitable for applications requiring multiple positive and negative bias voltage rails.

The LM5017 is a 100 V, 600 mA synchronous step- down regulator with integrated high side and low side MOSFETs. The constant-on-time (COT) control scheme employed in the LM5017 requires no loop compensation, provides excellent transient response, and enables very low step-down ratios. The on-time varies inversely with the input voltage resulting in nearly constant frequency over the input voltage range. A high voltage startup regulator provides bias power for internal operation of the IC and for integrated gate drivers.


Manufacturer Texas Instruments
Category AC/DC and DC/DC Conversion
Sub-Category DC/DC SMPS - Multi Output
Eval Board Part Number 1512-1007-ND
Eval Board Supplier American P.C.B Company
Eval Board -
Topology Step Down
Outputs and Type 4 Isolated
Voltage Out: Highest Current First ±5V, ±15V
Current Out 100mA, 50mA
Voltage In 17 ~ 32 V
Efficiency @ Conditions >75%, 24V in, 80 ~ 100% load
>75%, 17V in, 75 ~ 100% load
>70%, 32V in, 65 ~ 100% load
Voltage Out Range - Fixed
Features Current Limit (Adj. or Fixed)
Shutdown, Enable, Standby
Thermal Protection
Under Voltage Protection, Brown-Out
Switching Frequency 260 kHz
Standby Current [Typical] 50 µA
Quiescent Current [Typical] 1.75 mA
Component Count + Extras 30 + 13
Internal Switch Yes
Design Author Texas Instruments
Application / Target Market Automotive
Auxiliary Power Supply
Standby Current [Maximum] 225 µA
Quiescent Current [Maximum] - Not Given
Main I.C. Base Part LM5017
Date Created By Author 2013-08
Date Added To Library 2014-12

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