LT3471 simulation issue in LTspice

Rkhedkar986 on Apr 11, 2019

Hi,

I'm simulating LT3471 to give output of +/- 6V at 50mA each from 3.3V input supply. Negative side convertor is OK working at 1.2Mhz but positive side is working at around 7 Khz.

Is my converter going into some low frequency mode ? Why is it so ?

Thanks.

Top Replies

ADIApproved
Apr 12, 2019 in reply to Rkhedkar986 +1 verified
I would recommend you use the inductance values shown in the typical application, datasheet page 1, only adjust the feedback resistor values for 6V.

From the schematic you've sent it appears you are overloading…

0 ADIApproved

on Apr 11, 2019 2:10 PM
Hi,

This part has no low frequency mode. Your simulation is probably oscillating, skipping cycles, or it's simply hooked up wrong.

If you send a a copy of your simulation/schematic, it would help solve this riddle.

Cheers!
Cancel
Up 0 Down

Reply

Verify Answer

Cancel
0 Rkhedkar986 on Apr 12, 2019 7:06 AM in reply to ADIApproved

Blue trace is +6V which has ripples at around 7khz and green trace is -6V output. I want 40% inductor ripple current. Nominal load current is 100mA. I have kept higher inductor value to reduce ripple current but this is too high. Please advise.
Cancel
Up 0 Down

Reply

Verify Answer

Cancel
0 ADIApproved

on Apr 12, 2019 6:57 PM in reply to Rkhedkar986
I would recommend you use the inductance values shown in the typical application, datasheet page 1, only adjust the feedback resistor values for 6V.

From the schematic you've sent it appears you are overloading the positive supply, as R7 represents a 500mA load, and then you also have an additional load pulsing scheme.

The large inductance values you are using are not necessary for the 100mA load you say you need, and will make your converter more prone to oscillations.

I hope this helps.
Cancel
Up +1 Down

Reply

Reject Answer

Cancel