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Forum Post: TPS65072 -- backlight fails to turn back on after being powered off

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I have the same Problem like this old post: http://e2e.ti.com/support/power_management/pmu/f/200/p/139079/519274.aspx#519274

If I switch on the backlight driver all goes well, but if I switch off and on nothing happens (the time between of and on has no influence). The boost voltage is rising but the current sinks are without function.

My configuration on the own PCB is:

  • TPS65072
  • ISET1 = 124K
  • ISET2 = 249K
  • Inductor = VLF3010AT-220MR33 Datasheet: http://www.mouser.com/ds/2/400/e531_vlf3010a-18306.pdf
  • Both sinks connected together
  • Displaybacklight with 4 LEDs @ 20mA ~12,4V boost voltage

I have the same Problem with the TPS65070EVM-430. Changes on the demoboard:

  • ISET1 = 124K (10mA for every sink)
  • ISET2 = 249K (5mA for every sink)
  • ISET(Batt) = 1,13K
  • original LEDs disconnected 
  • Both sinks connected together
  • Displaybacklight with 4 LEDs @ 20mA ~12,4V boost voltage

I have connected 3/5 display LEDs together. -> No problems here on demoboard or own PCB

Any suggestions would be most appreciated!


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