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# LM5170EVM-BIDIR: LM5170-Q1-Board Startup

Part Number: LM5170EVM-BIDIR
Other Parts Discussed in Thread: LM5170-Q1

Hello

1. I am using EVM board for my application using as a boost mode 24/48 V, I have given a supply of 24 Volts and 2 A current in the begining with a load of 7 ohm, But there were no flash light ON for a boost mode. I did jumper settings right according to user guide. I can see some waveforms through ossciloscope but with distoritons.

2. What is the minimum current required to start-up the board?

Thank You

1. With a load of 7 ohm at 48V output, it will draw ~14A at 24V input. You need to set current limit more than 14A to power up the board.

2. I would recommend to set the current limit to more than 20A.

Best regards,

Feng Ji

• Hello Feng Ji

Thank you for the clarification, I do not understand how 14A it will draw, If I am not wrong for one phase it draw 48/7 = 6.8A and for two phase around 14A right?

But the input current is much less than this right? How can I calculate exactly through formula for inductor current ripples and input currents for the EVM?

The input power is almost the same as output power, so it will draw 13.6A from 24V input with 48V/6.8A output current.

Please find equation 43 of LM5170-Q1 datasheet for the current ripple.

Best Regards,

Feng Ji

• Thank You Feng JI

It is started now. But at the pins V48SN ans V12SN I cannot received the output and input voltages, I think it is OVP which is just less than 2 volts?

and, during boost mode I checked the LO pwm CYCLE has peak 10 Volts? Is that fine?

You can find these answers from the schematic.

V48SN and V12SN are signals used for OVP.

VCC is power by 10V, so you will see LO has a 10V amplitude.

Best Regards,

Feng Ji

• Thank You Feng Ji

But how can I measure the real output voltage at HV side? Because I did not see the testpoint for that.