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TPS62868: Vout register

Hong Jieun
Prodigy 240 points
Part Number: TPS62868
Other Parts Discussed in Thread: TPSM82864A, TPS62865

Hi,

According to datasheet, output voltage can be selected between two output voltage registers by the VID pin.

For TPS628680ARQY, the VSET/VID pin is connected to external resistor to set start-up voltage. 

Then after start-up period, Is output voltage set by Table 8-6?

How to set if I use same value after start-up, with start-up voltage?

  • 0
    TI__Guru*** 144230 points

    Hi,

    The VSET resistor setting sets the voltage in the Vout1 register.  So, you can set the voltage with the VSET resistor, and the device will operate at that voltage before and after startup.

    Does that answer your question?

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 240 points

    Hi, 

    1) Then, Can I use same voltage before and after startup by just setting the VSET resistor without using I2C?

    For example, If I use 0.55V both before and after startup, I need to connect 205kohm to VSET pin.

    Then, 0x8C(0.55V) value is set in Vout register1 automatically?

    (I want to set same voltage between before start up and after startup without changing the register value by I2C)

    2) Then Vout2 register is set only by PG device?(VID pin is pulled up to high) ex)TPS6286800CRQY

    3) I was wondering if I could know what situation change the vout after start up?

    Could you let me know the example?

  • 0 in reply to Hong Jieun
    TI__Guru*** 144230 points

    Hi,

    Yes, you don't need the I2C to operate the device.  If you don't want the I2C, you might look at the TPS62865 or the power module versions, TPSM82864A.

    1. Yes

    2. The Vout2 register is fixed at 0.9V.  You can only change this voltage through I2C.  For versions with PG, this register is not used at all since there is no VID pin to select it.

    3. Many processors dynamically change their voltage to change their performance.  Section 4 of this app note shows an example: https://www.ti.com/lit/an/sluaae9b/sluaae9b.pdf

    Chris

  • 0 in reply to Chris Glaser
    Prodigy 240 points

    Hi,

    Thanks for recommendation, but I need a buck converter which is Vout=0.55V for LPDDR5 VDDQ.

  • 0 in reply to Hong Jieun
    TI__Guru*** 144230 points

    Ah, you're right.  0.55V is just below what those 2 devices can output.

    Chris