LM5157-Q1: LM5157QRTERQ1 schematic review

Corey Axelowitz

Prodigy 40 points

Part Number: LM5157-Q1
Other Parts Discussed in Thread: LM5157

Please help review this schematic and provide feedback for LM5157QRTERQ1 SMPS - set up as a boost controller.

Input voltage (PBUS) is provided by a 3S battery = 8.1V to 12.6V

Output voltage = 24V

over 2 years ago

0 Brigitte over 2 years ago

TI__Guru 65390 points

Hello Corey,

The schematic seems to be ok, but I would recommend changing some components for a first prototype:

- Add a resistor in series to the VCC capacitor as mentioned in the datasheet.

- Add a resistor divider to the UVLO input to have the possibility to change the UVLO voltage if needed (you can populate just the upper one with 0 ohm at the beginning). Starting at the lowest UVLO voltage means high current at startup.

- Add a resistor to a high voltage to the MODE pin. If you do not need it fine, but if you find out you need it, it is good to have the place to add it.

In addition, I recommend using the quickstart calculator for checking the external values: https://www.ti.com/lit/zip/snvr511

Best regards,
Brigitte

0 Corey Axelowitz over 2 years ago

Prodigy 40 points

Hey Brigitte,

Here is with the updates you asked for, please provide feedback. I ran the calculator on my inductor and current ripple ratio will be ~11%, which sounds good to me.