TPS24710: why the gate of TPS24710 is alway low?

user5908676

Prodigy 20 points

Part Number: TPS24710
Other Parts Discussed in Thread: TPS24701,

Hi,

Following is the schematic of the power input circuit which uses TPS24701 as the hot swap controller.

the input voltage is 12VDC, and the max. current is about 15A-16A.

the design parameters in following figure is calculated according to the datasheet of TPS2471x.

Now, the Gate is always low after power on.

The voltage of EN pin is about 1.5V.

the output of FLTB is low, and that of PGB is high.

the wave of the Timer pin is zigzag wave.

BNX022 is a LC filter.

Why is TPS24710 always in Latch mode (the wave of the Timer pin is zigzag wave)?

Thank you.

over 6 years ago

0 Praveen GD over 6 years ago

TI__Guru 57737 points

Hi,

Welcome to e2e!

FLTB low and PGB high indicates that TPS24710 has remained in current limit long enough for the fault timer to expire and the Gate is pulled low.

While in latch mode, the TIMER pin continues to charge and discharge the attached capacitor periodically. This is not an issue. Refer to figure 34 in Datasheet.

Looks like you have a failed startup. What is the load during startup ?

Please use the design calculator available here : http://www.ti.com/product/TPS24710/toolssoftware and share it with us once filled.

0 user5908676 over 6 years ago in reply to Praveen GD

Prodigy 20 points

Hi Praveen，

Thank you for your rapid reply.

I tried two case during the startup:

1 no load

2 insert one daughter card as the load which the max power dissipation is about 180W(max current is about 15A ).

the debug results under above two cases are same, the output of GATE pin is always low.

thank you.

0 Praveen GD over 6 years ago in reply to user5908676

TI__Guru 57737 points

Hi,

It is possible to have a failed start up if the output doesn't charge before timer expires. Please fill the design calculator and share it with us to understand your system better/

Also please share startup waveform similar to figure 27 in datasheet with following signals - Vin, Gate, Vout, and Timer. This will help us understand why the GATE signal is going low.

0 Praveen GD over 6 years ago in reply to Praveen GD

TI__Guru 57737 points

Hi,

Can you please share the design calculator and waveforms as requested in above message.

0 Praveen GD over 6 years ago in reply to Praveen GD

TI__Guru 57737 points

Hi,

Hope your query is solved. In case you still have questions, reply to this thread or create a new one.

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TPS24710: why the gate of TPS24710 is alway low?