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TPS652170: TPS652170 replaced TPS65217C, not working as expected.

Ryan G
Prodigy 60 points
Part Number: TPS652170
Other Parts Discussed in Thread: AM3358, TPS65217,

Hello,

In a design we orginally were using the TPS65217C, due to availibility reasons we decided to switch to the TPS652170. They have the same footprints/pinouts, nearly identical datasheets but there is a major difference that is causing a problem. 

Upon bootup, the TPS65217C SYS automatically comes up and outputs 5V, sending power to the rest of the LDOs and VDCs to turn on. The AM3358 can then configure the TPS65217C  via I2C to output the desired voltages.

When using the TPS652170 in replace of the 217C, upon bootup there is no output voltage on SYS, which then prevents the other LDOs and VDCs from turning on as well as preventing the AM3358 from powering and cannot reconfigure the PMIC via i2C. Does the the 2170 need a seperate self powered device to configure it with I2C?

Are there any other differences I am missing?

  • +1
    TI__Mastermind 32340 points

    Hi Ryan, 

    The key difference between the TPS65217C and TPS652170 is that the TPS652170 is a user programmable version of the device. It therefore does not have the power up sequence preprogrammed the same way the TPS65217C does.

    This can be seen in the register map section of the TPS652170 datasheet. The sequence registers, which begin on page 65, are default set to all 0's whereas the power up sequence is defined on the TPS65217C. 

    When the TPS652170 device boots up there should be an output on VSYS, but no output is expected from any of the LDOs or BUCK regulators. It appears you will need to use a separate powered device to enable the various outputs via I2C, then the AM3358 can be used to do the rest of the I2C configuration. 

    Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 60 points

    I appreciate the quick response. That is a good catch. It'd be nice if it were worded somewhere clearly that this device has no default boot sequence because that requires a design change in order to get proper functionality. The two datasheets are worded nearly identical with no mention of it not having a default boot sequence. In the TPS652170 datasheet on page 18, it shows "Figure 4: Default Power-Up Sequence for the TPS65217A Device". This made me think that the default power sequence was the same as the 217A, and that the customer could change it as needed. In the description of page 18's figure 4, it says to look at the "The Powering the AM335x with the TPS65217x" PDF to see the power sequences of each device, but it also does not mention anything about the 2170 device.

  • 0 in reply to Ryan G
    TI__Mastermind 32340 points

    Hi Ryan, 

    Thank you for the feedback. I have made note and will work to either adjust the datasheet or create new documentation to make the difference between the TPS652170 and TPS65217x devices more clear. 

    Best Regards,

    Garrett