TPS65921: VRTC.OUT without 1uF cap impact

Gunter Schmer

Part Number: TPS65921

Hi,

a customer is chasing an AM37xx USB EHCI reset lock issue (this is NOT using the USB PHY in the TPS65921), but we are checking all power rails for this. During that investigation we found that the VRTC.OUT did not have the 1uF cap in the customer HW. What could be the impact of that missing cap?

Regards,

--Gunter

over 9 years ago

0 Tuan Tran74 over 9 years ago

TI__Mastermind 18890 points

Hi Gunter,

The TPS65921 uses VRTC.OUT as an internal power supply for some of our digital circuits such as the 32KHz oscillator and the PLL circuit. We rely on the 1uF capacitor to both filter the voltage and keep it stable so you can get the reset issue you are having without this capacitor.

Thanks Tuan

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TPS65921: VRTC.OUT without 1uF cap impact