TPS568215: PG start-up delay

Aaron Hsu

Intellectual 565 points

Part Number: TPS568215
Other Parts Discussed in Thread: TPS568230

Dear All

What is the PG delay(PG start-up delay ) of TPS568215?

I think it is Delay 200us after FB PIN reaches 0.558V, but the measurement result is not

1. Delay 200us after FB pin reaches 0.6V

2. Delay 200us after FB PIN reaches 0.558V?

FB pin =0.6V 100%

FB pin =0.558V 93%

CH1 FB

CH2 PG

over 4 years ago

0 Xueliang Zhang over 4 years ago

TI__Expert 4360 points

Hi Aaron

Could you measure the delay of Vout relative to PG? We usually do not measure the FB pin directly, because noise may not be introduced. Thanks!

Xueliang Zhang

0 Aaron Hsu over 4 years ago in reply to Xueliang Zhang

Intellectual 565 points

Hi Xueliang

VOUT=3.3V

VIN=12V

CH1 =VIN

CH2=EN

CH3=VOUT

CH4=PG(POWER GOOD)

0 Xueliang Zhang over 4 years ago in reply to Aaron Hsu

TI__Expert 4360 points

Hi Aaron

The 200us delay from FB to PG is during the normal working regulation period. When the chip is started, the chip is in the soft start period, and the delay time is not necessarily 200us.

Xueliang Zhang

0 Aaron Hsu over 4 years ago in reply to Xueliang Zhang

Intellectual 565 points

Hi Xueliang

Can we simply regard it as Delay 200us after FB pin reaches 0.6V?

0 Xueliang Zhang over 4 years ago in reply to Aaron Hsu

TI__Expert 4360 points

Hi Aaron

1. This understanding of 200us delay is wrong. For example, when the chip is working, when FB is lower than 84%, PG becomes low. When FB returns to 93%, it will delay 200us, and then PG becomes a high state.
2. When the power is turned on, the delay of FB and PG cannot be determined.

xueliang

0 Aaron Hsu over 4 years ago in reply to Xueliang Zhang

Intellectual 565 points

Hi Xueliang

What is the PG delay(PG start-up delay ) of TPS568215?

So PG delay can't provide it?

Why can TPS568230 provide it?

+1 Xueliang Zhang over 4 years ago in reply to Aaron Hsu

TI__Expert 4360 points

Hi Aaron

Sorry make you confusion about item2 I mentioned in last response, The delay of PG should be considererd in design but just not shown in the datasheet. I checked on EVM board. the delay from Vout ready(100%) to PG high is about 200us. hope this data will be helpful for you.

VIN=12V, Vout= 1.2V, CH1=PGOOD, CH2=SS, CH3=Vout, no load

Xueliang

Power management

Power management forum

TPS568215: PG start-up delay