TPS65981: External reset signal, MRESET and RESETZ

Oba

Genius 15750 points

Part Number: TPS65981

Hello,

I can’t understand the role of MRESET and RESETZ of TPS65981.

What I actually want to do is to reset TPS65981 externally like putting external reset IC.

But RESETZ is output and I feel MRESET is not a kind of usual H/W reset input like usual reset input of MCU.

What is the role of MRESET and RESETZ?

Is it possible to reset this device by external signal?

Regards,

Oba

over 5 years ago

0 Kedar Manishankar over 5 years ago

TI__Mastermind 24075 points

Hi Oba,
Yes, RESETZ is output and MRESET is input. A hard reset happens when VIN_3V3 drops below the undervoltage threshold, and when this occurs it sets the external RESETZ indicator. Another way to set RESETZ output is with the use of MRESET. MRESET is a digital I/O pin which forces RESETZ to assert, and by default MRESET is active high. (can also be configured to be active low). MRESET can be used to reset a co-processor and just affects the RESETZ output.
To do a hard reset with an external MCU you can write over I2C, the 4CC comamand for Hardware reset of TPS65981 (GAID cold reset request).

0 Oba over 5 years ago in reply to Kedar Manishankar

TI__Genius 15750 points

Hello Kedar,

Thanks for your reply.
So MRESET is not hardware reset to TPS65981. It is just input to control RESETZ output.
There is no way to assert hardware reset to TPS65981 except for VIN_3V3 POR or sending certain I2C command.

Correct?

Regards,
Oba

0 Kedar Manishankar over 5 years ago in reply to Oba

TI__Mastermind 24075 points

Hi Oba,
You are correct in your understanding. VIN_3V3 removed or GAID 4CC command over I2C are the 2 ways you can implement hard resets.

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TPS65981: External reset signal, MRESET and RESETZ