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TPS65086: Programmable Vout Steps & Power On State

Go Bravos
Expert 6090 points
Part Number: TPS65086

Hi team,

The data sheet states that the adjustable Vout steps can be either 10mV or 25mV programmable at the factory. How do we indicate that in the part number ordering?

Also when the part is first powered on and  before being programmed, do all the regulators default to 0V output?

Thank you.

  • 0
    TI__Genius 17380 points

    Hi Brad,

    I've included below a summary of the TPS650860 OTP which wasn't well documented. Newer OTPs like the TPS650864 family have been and will be better documented and eventually we will go back and update the TPS650860 datasheet to be more descriptive.

    Note that for now this part's non volatile memory is only factory programmable. We are working to make it customer programmable but it is a complicated process that is still likely several months away. For setting the volatile memory settings, they default to the values below, however if the CTLx pins are all kept low, then only LDOA1 will turn on by default. At that point the microcontroller can set all the settings (BUCK1_VID = x, BUCK1_SLPVID = x, BUCK2_VID = y, BUCK2_SLPVID = y, etc) and then enable each rail (BUCK1_EN = '1', BUCK2_EN = '1', etc.) in the desired sequence. If power is lost or a power fault occurs, the part will lose these settings, so the microcontroller needs to set them again.

    Voltages:  
    BUCK1 1.05
    BUCK1 (alternate) 1.05
    BUCK2 3.3
    BUCK2 (alternate) 3.3
    BUCK3 2.5
    BUCK3 (alternate) 2.5
    BUCK4 2.8
    BUCK4 (alternate) 2.8
    BUCK5 1.8
    BUCK5 (alternate) 1.8
    BUCK6 1.5
    BUCK6 (alternate) 1.5
    BUCK6 (alternate 2) 1.5
    LDOA1 3.3
    LDOA2 0.7
    LDOA2 (alternate) 0.7
    LDOA3 1.2
    LDOA3 (alternate) 1.2
     
    Buck Step Size:  
    BUCK1 10 mV
    BUCK2 25 mV
    BUCK3 25 mV
    BUCK4 25 mV
    BUCK5 25 mV
    BUCK6 10 mV
     
    Alternate Voltage Pin  
    BUCK1 CTL3 (masked)
    BUCK2 CTL3 (masked)
    BUCK3 CTL3 (masked)
    BUCK4 CTL3
    BUCK5 CTL3
    BUCK6 CTL6
    LDOA2 CTL3
    LDOA3 CTL3
     
    LDOA1 / SWB2 Setup:  
    LDOA1 in sequence? No
    SWB1 and SWB2 merged? No
    SWB2 or LDOA1 Emergency Shutdown Behavior Yes
     
    Load Switch Power Good Setting:  
    SWA1 PG Voltage 3.3 V
    SWB1 PG Voltage 1.8 V
    SWB2 PG Voltage 1.8 V
     
    GPO Setting:  
    GPO1 by PG or I2C? Default state if I2C? I2C, High
    GPO2 by PG or I2C? Default state if I2C? I2C, Low
    GPO3 by PG or I2C? Default state if I2C? Power good 
    GPO4 by PG or I2C? Default state if I2C? Power good 
     
    BUCK AUTO or Force PWM:  
    BUCK1 Auto
    BUCK2 Auto
    BUCK3 Auto
    BUCK4 Auto
    BUCK5 Auto
    BUCK6 Auto
     
    Discharge Resistor Setting:  
    BUCK1 100 Ohm
    BUCK2 100 Ohm
    BUCK3 100 Ohm
    BUCK4 100 Ohm
    BUCK5 100 Ohm
    BUCK6 100 Ohm
    LDOA1 100 Ohm
    LDOA2 100 Ohm
    LDOA3 100 Ohm
    SWA1 100 Ohm
    SWB1 100 Ohm
    SWB2 100 Ohm
    VTT No
     
    Power Fault Masked by Default:  
    BUCK1 No
    BUCK2 No
    BUCK3 No
    BUCK4 No
    BUCK5 No
    BUCK6 No
    LDOA1 Yes
    LDOA2 Yes
    LDOA3 No
    SWA1 Yes
    SWB1 Yes
    SWB2 Yes
    VTT No
    V5ANA Yes
     
    GPO Type  
    GPO1 Push Pull
    GPO2 Open Drain
    GPO3 Open Drain
    GPO4 Open Drain
  • 0 in reply to Kevin LaRosa
    TI__Expert 6090 points

    Hi Kevin,

    Can you confirm the device is fully programmable by the microcontroller (including step size & output voltages)? You mentioned above the microcontroller can set all the settings, but I read that the step sizes are fixed to the default values and these cannot be modified by a microcontroller – from the datasheet sect 5.3, page 21:

    Thanks for your help.

  • 0 in reply to Go Bravos
    TI__Genius 17380 points
    Hi Brad,

    You are correct, step size is not a user accessible setting. For BUCK3/4/5, they support full range with 25 mV step size, but BUCK1/2/6 need to be chosen carefully since BUCK1 and BUCK6 can only go up to 1.67V and BUCK2 can only go as low as 1V.
  • 0 in reply to Kevin LaRosa
    TI__Expert 6090 points
    Hi Kevin,
    Is the limiting factor on BUCKS 1, 2 and 6 the step size being fixed at 10mV and the 25mv step size is not available for these?
    In the data sheet Fig 1-1 it appears that there are two ranges 1V-3.35V for 25mv steps and 0.41-1.67V for 10mV step sizes. Also I think this is confirmed by tables 5-1, 2, and 3. What have I missed here?

    Thank you.
  • 0 in reply to Go Bravos
    TI__Genius 17380 points
    Hi Brad,

    BUCK1 and BUCK6 are fixed at 10 mV step size for this OTP and BUCK2 is fixed at 25 mV step size for this OTP. So BUCK1 and BUCK6 have the low range (0.41 to 1.67) and BUCK2 has the high range (1 to 3.575). If the customer application requires VOUT > 1.67 V options than we can support with TPS650860, the TPS65086470 (same part, just different OTP settings) has BUCK6 also with 25 mV step size. However, the TPS65086470 doesn't have LDOA1 on by default so it can't power a microcontroller.

    I just mean to say that if customer design requires 3.3V, 1V, and 1.2V with high current (>3A), then BUCK2 should be 3.3V, BUCK1 should be 1V, and BUCK6 should be 1.2V.

    By the way, if you check out the TPS65086470 datasheet you'll see that we qualified 3.3V input to the converters (BUCK3/4/5) so you could have BUCK2 feed back into them as long as it is enabled first. This may help simplify designs. Haven't gotten around to updating the TPS650860 datasheet yet.
  • 0 in reply to Kevin LaRosa
    TI__Expert 6090 points
    Hi Kevin,
    I am working with P/N TPS650860A0RSK. If I understanding your comments we don’t have an issue.
    We need the following:
    • BUCK 1 25mv Steps
    • BUCK 2 25mv Steps
    • BUCK 3 25mv Steps
    • BUCK 4 25mv Steps
    • BUCK 5 25mv Steps
    • BUCK 6 25mv Steps or 10mv steps.
    • We need LDOA1

    If my understanding of your comments is correct then P/N TPS650860A0RSK should meet the above requirements. Please confirm. As for
    TPS65086470 according to the data sheet the BUCK 1 is set to 10mV.

    Thank you.
  • 0 in reply to Go Bravos
    TI__Genius 17380 points
    Hi Brad,

    From above, the TPS650860 is set up like this:

    Buck Step Size:
    BUCK1 10 mV
    BUCK2 25 mV
    BUCK3 25 mV
    BUCK4 25 mV
    BUCK5 25 mV
    BUCK6 10 mV
  • 0 in reply to Kevin LaRosa
    TI__Expert 6090 points
    Hi Kevin,
    It looks like there will be an issue with BUCK1. Am I misreading this or what would you advise as the best way to accomplish this?

    Thank you.
  • 0 in reply to Go Bravos
    TI__Genius 17380 points
    Hi Brad,

    If you need 2 controllers with 25 mV and 1 with 10 mV, then the TPS65086470 may be a better option, just swap the rails assigned to BUCK1 and BUCK6; would that work?
  • 0 in reply to Kevin LaRosa
    TI__Expert 6090 points
    Hi Kevin,
    Thanks for the clarification. What would be the ramifications for BUCK 1 if the feedback voltage is ½ the output voltage through a voltage divider?
    Would we be able to have 20mV steps and therefore Vout 0.82V to 3.34V? This would give us what we want and save an LDO to power the controller.

    Thank you.
  • 0 in reply to Go Bravos
    TI__Genius 17380 points
    Hey Brad,

    Ramifications would be expected to be minimal as long as the resistances aren't too big. Our internal resistor divider is ~400kΩ minimum so the external will probably want to be in the range of ~40kΩ to avoid having too much error. We haven't done full validation on external resistor divider so it's not guaranteed, but we don't expect issues. As long as customer does some testing on the EVM (we have spots on it for external resistor divider), it should be fine.
  • 0 in reply to Kevin LaRosa
    TI__Expert 6090 points
    Hi Kevin,
    In follow-up to your comment above, what is the maximum value of the internal resistor divider?
  • 0 in reply to Go Bravos
    TI__Genius 17380 points

    Hi Brad,

    For controllers, internal feedback is done with a circuit which uses a nominal 3.32 uA (10 mV) or 8.31 uA (25 mV), so resistance is voltage setting dependent. For 1.05V (10 mV step size) / 3.32 uA, resistance should be approximately 316 kohm. If VID value is set to 1.67 (max), then the resistance should be around 500 kohm.