TPS65170: Power On/Off sequencing

Zhen Luo18

Part Number: TPS65170

Dear all,

I'm working on a power management solution for source driver IC of LCD panel. I wish to use TPS651XX family chips to implement the correct power on and off sequencing defined by source driver IC provider.

The power on/off sequencing is as following:

Actually, the power on sequencing of TPS65170 based on its datasheet is matched with the required sequence. However, there is no information of power off sequencing mentioned on its datasheet. I ordered one EVM board for testing and here is my result. As you can see, Vlogic goes away before Vs goes to GND. The load is open in my test. Could any expert could help me how to control the power off sequencing of TPS65170. And is this chip the best option to implement the power management of SDIC?

over 7 years ago

0 Liaqat Khan over 7 years ago

TI__Mastermind 18550 points

Hello,
I will try to find the power down sequencing information and will provide my feedback in the next couple of days.
Kind Regards,
Liaqat

0 Zhen Luo18 over 7 years ago in reply to Liaqat Khan

Prodigy 60 points

Hi Liaqat,

Thanks in advance. The schematic of TPS65170EVM is as following:

0 Liaqat Khan over 7 years ago in reply to Zhen Luo18

TI__Mastermind 18550 points

Hello Zhen Luo,
I looked into it and in fact TPS65170 only has power up sequencing and no specific power down sequencing. Basically, as you are seeing in your scope plots, all supplies are disabled at about the same time and which one goes down first vs others is a function of what voltage that supply was at before shutdown, the output capacitance on that supply and any leakage load path. TPS65170 does not control the power down of supplies in any particular order.
Kind Regards,
Liaqat

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TPS65170: Power On/Off sequencing