TPS61196: The TPS61196 can not work

xu xuan

Part Number: TPS61196

The TPS61196 does not work. The schematic like this. We never make it to the point where the buck converter turns on (never saw a single pulse on the gate of Q1). The Boost switcher can not turn on and the output voltage(VCC_LED) before the Boost switcher turns on is around 23V (24V -diode drop). The LEDs are on a different board where we terminate each LED string (16 of them) with a 10M to ground, Each string is composed 16 LEDs. The voltage drop across each LED is 3V.

over 6 years ago

0 Sean Zhou over 6 years ago

TI__Mastermind 22745 points

Hi Xuan sir,

For the debug side of view, I suggest to disable five channels and only leave one channel to re-test. And I upload one calculation tools for your reference.

TPS61196-Calculation-Tool_update.xlsx

Regards
Sean

0 xu xuan over 6 years ago in reply to Sean Zhou

Prodigy 40 points

Hi Sean,

Thank you. I disable the other five channels and only leave one channel to re-test, but the problem still exists. The TPS61196 does not work, but the VDD pin is ok and the voltage is 5.98V. The Boost switcher can not turn on and the output voltage(VCC_LED) before the Boost switcher turns on is around 23V (24V -diode drop).

0 Sean Zhou over 6 years ago in reply to xu xuan

TI__Mastermind 22745 points

Hi Xuan,

I suggest requesingt a TPS61196EVM http://www.ti.com/tool/tps61196evm-600 to compare with your board, that mat help you quickly identify the issue.

Regards

Sean

0 xu xuan over 6 years ago in reply to Sean Zhou

Prodigy 40 points

Hi Sean，

Thank you. According to the circuit of a typical application, the schematic is mainly based on the test board (TPS61196EVM). The current of each channel is set to 150 mA and the voltage is 70 V. But only a single channel works, not two or more channels. If more than one channel work, the chip will be broken (10 pieces have broken). Can you give detailed advice？

0 Sean Zhou over 6 years ago in reply to xu xuan

TI__Mastermind 22745 points

Hi Xuan,

Since one channel can work fine and more than one channel dones't work fine, it may has trggered the internal current limit, you can observed the current waveforms of the inductor to make sure whether it has triggered the current limit. I suggest to increase the supply voltage or increase the inductor to 47uH or 68uH to test whether this phenomenon still there or not.

Regards

Sean

0 xu xuan over 6 years ago in reply to Sean Zhou

Prodigy 40 points

Hi Sean,

When the tps61196 power on, it will be broken within 10s and it can no longer work. So, I can not observe the current waveforms of the inductor. By the way, the supply voltage is 24 V that high enough to increase again. But the inductor is 22uH (current limit is10A). I can not sure the resson is the inductor.

0 Sean Zhou over 6 years ago in reply to xu xuan

TI__Mastermind 22745 points

Hi Xuan,

Actually I don't know what's wrong with your problem, it maybe helpful if you could share some waveforms.

Regards

Sean

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TPS61196: The TPS61196 can not work