problem with dc-dc driver using TPS61165

emil jose

Prodigy 170 points

Other Parts Discussed in Thread: TPS61165

Dear all

i'm going to done a dc dc driver using TPS61165

Vin-3 to 5V dc

Vout- 12V

Iout - 350mA

But, when i connect the supply 3V or 5V the output is just only 5V. and the curent is not controlled, it varies from 3V input to 5V input dc. Here me attached my circuit with component values.

over 12 years ago

0 Avi Chami1 over 12 years ago

Mastermind 7395 points

Did you check he voltage at FB?

0 emil jose over 12 years ago in reply to Avi Chami1

Prodigy 170 points

as per calculation (Vfb= ILED*REST), feed back voltage is 0.21V. but i didn't get that voltage, using oscilloscope measuring. How can i achieve, that calculated feed back voltage.

COMP pin voltage is in milli voltage range, only the control pin voltage is high (5V)

0 emil jose over 12 years ago in reply to emil jose

Prodigy 170 points

reply me please.............................................

0 David Do over 12 years ago in reply to emil jose

Prodigy 10 points

You may want to check the inductor for saturation rating. The inductance drops when it is saturated then it will trigger the current limit.

0 Dave Neale over 12 years ago

Prodigy 60 points

Hi Emil, the physical layout of the TPS61165 is critical. ALL connections between the chip itself, Input supply, the inductor, diode and output cap need to be short and heavy tracks otherwise noise can be induced on the feedback pin causing erratic sensing of the output current. Ask your TI rep for an Analog Evaluation Module for this device and you will get some idea of what is required for correct operation. This chip does work well if given the correct conditions.

Regards, Dave Neale

0 marc caus over 12 years ago in reply to Dave Neale

Prodigy 20 points

I think its' ok. If there 's an 0.21v in fb it equla at 0.21V/0.57ohms=368mA. Can you tell us which does leds are?

marc

Power management

Power management forum

problem with dc-dc driver using TPS61165