TPS61178: TPS611781 OFF Delay Time issue

Hi Vincent,

There is no spec about the delay time.

I can give you a test result for reference.

From EN pin11(Low) to SW pin7(stop) 270ns.

From EN pin11(Low) to DISDRV_ pin9 (High) the time is not able to test.

The DISDRV pin gets an internal 55 µA (typical) sink current. It will not go to high as you mentioned.

When the EN is low, the sink current stop to sink and it becomes high resistance.

the DISDRV voltage changes with the resister and capacity on the gate.

Best Regards

Fergus

Dear Sir:

1.From EN pin11(Low) to SW pin7(stop) 270ns.

--> From EN pin11(Low): It means the EN (pin11) Low is VEN_L (EN Logic Low threshold) 0.4V(min).

Is it correct?

2.Regarding the TPS611781 start time.

Soft Start:

2-1 tSTARTUP Startup time typical 3.2 ms.

Does Startup time define the Max and Min Startup time?

2-2 Pre charge time:

tPRE_CHARG Pre charge time typical 2.6 ms.

Does Pre charge time define the Max and Min Startup time?

3.The input VIN(P12) power(BAT_IN) of TPS611781:4V (Always be powered- Connect Battery ).

The output VOUT(P8) power(VBUS) of TPS611781:5V.

When the EN pin11 changes from Low(0V) to High(>=1.2V(max)).

It will turn on the soft -start Time. Is it correct?

[ VEN_H EN Logic high threshold: 1.2V(max).]

4.Due to the VIN(P12) power(BAT_IN) of TPS611781:4V (Always be powered- Connect Battery ).

The soft start time has the tSTARTUP (Startup time) only.

The soft start time excludes the tPRE_CHARG (Pre charge time).

Is it correct?

Please check to reply us asap.

Thanks a lot.

Best regards,

Vincent

Hi Vincent,

1. Yes.

2. The Min and Max Startup time are 3ms and 3.4ms,

and the Min and Max Pre charge time are 1.8ms and 3.4ms.

3. No. it will still go through pre charge(2.6ms) and soft start(3.4ms).

Total start time will be 6ms.

4. The soft start will always include the pre charge time.

Best Regards

Fergus

Dear Fergus:

Q:

3.No. it will still go through pre charge(2.6ms) and soft start(3.4ms).

Total start time will be 6ms.

-->

1.The soft-start time includes the pre charge(2.6ms-typ.) and Startup time(3.2ms)

Total soft-start time will be 5.8ms.( 2.6ms+3.2ms )

Is it correct?

2.The input VIN(P12) power(BAT_IN) of TPS611781:4V (Always be powered- Connect Battery ).

The output VOUT(P8) power(VBUS) of TPS611781:5V.

When the EN pin11 changes from Low(0V) to High(>=1.2V(max)).

It will start the soft -start Time(5.8ms). [ includes the pre charge and Startup time(3.2ms).

After the soft -start Time(5.8ms) (VOUT(P8) low(0V))done.

The output VOUT(P8) power(VBUS) will start from low(0V) to high(VBUS).

Is it correct?

[ VEN_H EN Logic high threshold: 1.2V(max).]

Please check to reply it asap.

Thanks

B.R

Vincent