TPS92692-Q1: about the tps92692 Start Time issue

qinlei

Part Number: TPS92692-Q1
Other Parts Discussed in Thread: TPS92692

hello

when i use the TPS92692, i found that The start-up time of the chip varies with different PWM input duty cycles.

please refer to the follow picture.

the blue line is the input voltage ,and the yellow line is the output current, left picture the pwm duty is 15%,and the right picture pwm duty is 50%,

It is obvious that there is a significant difference in startup time,please help Analyze the reasons.

thank you

best regards

over 1 year ago

0 Tuan Tran74 over 1 year ago

TI__Mastermind 18890 points

Hello,

This is the expected response from the TPS92692. During PWM LO the part will tri-state the COMP pin and the Soft-Start pin. We do this so we have soft-start even thru PWM dimming.

Thanks Tuan

0 qinlei over 1 year ago in reply to Tuan Tran74

Intellectual 430 points

hello, what this Sentence mean? please help explain

"During PWM LO the part will tri-state the COMP pin and the Soft-Start pin"

0 Tuan Tran74 over 1 year ago in reply to qinlei

TI__Mastermind 18890 points

Hello Qinlei,

That means that if PWM input is LO then there is no current to ramp up Soft-Start. Soft-Start will only ramp up and be active if PWM is HI and this is why you get time for Soft-Start with different PWM inputs.

Thanks Tuan

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TPS92692-Q1: about the tps92692 Start Time issue