TPS62864: registers and set voltage issue on TPS62864

Hi Chris,

      For VID version,   when pulling up or down the VID pin, we can use two Vout registers. Low for reg1 and high for reg2. Both registers could be set to regulate the Vout. But you said the reg 2 always has 0.9V which makes me confused. what are the differences on the these registers expect the I2C address? and why we have two vout registers?

Chris Glaser said:

Vout register 1 is loaded with the voltage from the VSET resistor. Vout register 2 always has 0.9V. You can change both of these voltages with I2C and use the VID function to switch between them during operation (if you want to).

  yours

nan

Hi Nan,

Vout register 2 always starts with 0.9Vout loaded, but you can change that value with I2C.

Chris

Hi Chris,

     According to your answer, that is the reason why the reg 2 set 900mV as default value.

     But when i pull down the DIV pin(to use reg1 without default value), what kind of voltage would the TPS62864  output?

Hi Nan,

This app note, found on the product page, explains how this dual function (VSET and VID) works: https://www.ti.com/lit/an/slvaf64a/slvaf64a.pdf 

You need to attach a resistor to GND on the pin, and then drive it high or low after startup.

Chris

And the resistor sets the startup voltage and the Vout 1 register values.  So, the register values change with different resistor values, according to table 8-1.

Chris