TPS40211: Driver stops after a short time

Stefan Strobl

Part Number: TPS40211

Hello,
i use the TPS40211 with the electric diagramm shown here.
The LEDs start to light, but after a short time (0,2 to 1 sec.) something turn the driver off.
I tried to decrease the current sense resistors but no change.
Any idea?

Thank you
Ewald

Pathfinder_Front(Page2).pdf

over 7 years ago

0 Youhao Xi over 7 years ago

TI__Guru* 78400 points

Its not clear what is connected to the dimming control FET's gate (T3 of your schematic. There should be a pull-down resistor (say 10k to 100k) from the gate to gnd.

0 Stefan Strobl over 7 years ago in reply to Youhao Xi

Prodigy 70 points

A PWM output of my CPU board is connected to the gate. Pulling it to GND makes no difference in the behaviour.

0 Garrett Roecker over 7 years ago in reply to Stefan Strobl

TI__Mastermind 21720 points

Hi Stefan,

Please try removing D5 and R18. The best way to implement over voltage protection is to use the FB pin not the ISNS pin. Please take a look at PMP10291 using the TPS40211. The over voltage zener is connected to the FB pin between two resistors

Also Reducing R11 to 100 Ohm is advised.

Thanks,

Garrett

0 Stefan Strobl over 7 years ago in reply to Garrett Roecker

Prodigy 70 points

Thank you.
It works fine now.

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TPS40211: Driver stops after a short time