TLV62569: Overshoot during Power OFF

Hello Brain,

Thank you for reaching out,

Let me look into other waveforms such as VFB, SW and inductor current at the point of overshoot to understand the cause. I will perform the measurements tomorrow and and get back to you.

Thank you & regards,

Moheddin.

Hi Moheddin

I measure VFB, SW and inductor current at the at the point of overshoot for reference.

R1: 150K, R2: 33K, C5: 100pF, No Load

R1: 9.1K, R2: 2K, C5: 10nF, No Load

C5 is for Load transient: 0.15A~1.35A, 0.5ms/0.5ms, 1A/us, Vo = 3.135~3.465V

Thanks~

Hello Brain,

Thank you for providing the waveforms,

This short period of overshoot is due to the 100% duty cycle mode operation when the Vin is very close to Vout. You can observe this in the below waveform, If I shut down the device by shutting down the power supply keeping the EN high, the device still operate until the Vin is above UVLO and in this condition you can observe this behavior.

In other case if you shutdown the device by keeping the VIN high and and pulling the EN low you don't see this behavior as shown below.

If it's a new project I would recommend to use our value line hero device TPS62A02 data sheet, product information and support | TI.com

Thank you & regards,

Moheddin.

Hi Moheddin

May I know why there is no overshoot on TLV62565? 

I use the same circuit design.

Thanks~

Hello Ted,

There will be internal threshold of Vin - Vout which defines the device to enter into 100% duty cycle mode. The Vout overshoot also depends upon at what point you are entering 100% duty cycle mode based upon the internal threshold of the device. 

Ted Yang said:

May I know why there is no overshoot on TLV62565? 

This might be due to the lower threshold value.

Thank you & regards,

Moheddin.