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TPS1H200A-Q1: Fault Detection Issue

Songzhen Guo
Intellectual 2840 points
Part Number: TPS1H200A-Q1

Hi Experts,

TPS1H200A-Q1 is under evaluation on customer side. There are several issues occur on customer side, could you help on those issue? Thanks. 

  1. When the device is Latch-off mode, when the overcurrent occurs, it takes tcl(deg)+tdl1+tdl2 to shut the output. When the overcurrent time is less than tcl(deg)+tdl1+tdl2, the output still work well and the fault is high. Is it normal? We didn’t see this scenario description in datasheet.
  2. Basing on the test result and understanding of scenario 1, we find that: when the overcurrent is occur, the overcurrent time is less than tcl(deg)+tdl1+tdl2 and bigger than tcl(deg), the fault will enter low level then go back to High level, then the overcurrent occur again in the middle of tcl(deg) ~ tcl(deg)+tdl1+tWe find that the fault go to low level and the OUT is down due to the fault low level. See the left picture below: CDelay=4.7uF. The tdl1+tdl2 ­is set to 2mS. Could you comment on this?

            

Best Regards

Songzhen Guo

  • 0
    TI__Mastermind 32650 points

    Hi Songzhen,

    How is the fault implemented on the device? Is the customer using an eload here? Please ask the customer to not use an eload especially if it is set to the constant current mode.

    In the latch off mode, current has to flow through the device for the delay duration in the current clamping state for it to turn off and then latch off. The green waveform shows that the current goes down to 0 after the turn on event. The FLT pin is responding to the current limit fault and this may take up to 500us to respond after turn on but since the current limit goes away, then the fault recovers.

    Please note that this device also has open load detection in the on state, so if no current flows through the device, the FLT pin will pull low.

    Then if there is a second current limit fault espescially one that triggers when the channel is enabled, this can lead to a high inrush of current through the device. The response to this situation is to immediately turn off. This is to allow time for the closed loop protection to engage. 

    The the device recovers by turning on into the current limit. Do note that the device also turns off due to thermals and if the device hits the thermal shutdown threshold before the delay time, it will still turn off.

    Thanks,

    Shreyas