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TPS65910 Questions

Paul Joseph
Expert 2795 points
Other Parts Discussed in Thread: AM3703, TPS65910

Developing a new system based on the AM3703 Microprocessor

and selected the TPS65910 for power sequencing. The primary system requirements

include the following;

 

Power Supply Main (VBAT) = 5.0V (switched)

Boot Time Total                  = 500mS max (from VBAT insertion).

 

There are several issues, encountered, with this system that need to be resolved.

 Issue #1 Auto Power-On: Can the TPS65910 be configured for auto power-on,

using PWRON & PWERHOLD or other means, when the VBAT supply is inserted?

There is no on/off switch in the design.

 Issue #2 Power-Down Timing: The system main power is switch-off at the end of the

work day. Can memory corruption or damage result in this action? A backup capacitor

is not included in the design.

 Issue #3 32.768 KHz Clock Stabilization Time: The crystal clock mode stabilization

time is ~2 seconds, which is too slow. An external oscillator is a consideration, with

BOM cost and board space penalties. Is there other possibilities, such as the internal

RC oscillator, that may be viable?

  • 0
    TI__Genius 15100 points

    Hi,

    #1: The default setting is such that the device powers up on valid VBAT. Device has a power switch option (PWRON), this switch will power ON the device on a negative transition and will power OFF the device on long press.

    #2: This would be an abrupt shutdown for the device, I dont see any reason why there would be any corruption. On next power on the device will power up as expected and will power on the processor. A back up option is possible - coin cell or super cap.

    #3: That is the max time, it also depends on which crystal you are using. Internal oscillator is an option but is not available in this part number.

  • 0 in reply to Gandhar Dighe
    Expert 2795 points

    Gandhar:

    Thank you for the response.  

    A potential two second startup time is way more than our system requirements, we need about 500ms, could be stretched somewhat.

    It would have been great if the internal RC oscillator was available for the TPS65910 mode.  It's available for the other boot mode of the device, strange that it's not for this processor, are there any other options?

  • 0 in reply to Paul Joseph
    Expert 2795 points

    Gandhar:

     

    Also, wondering, if there was not a technical reason for not using the internal oscillator, could the EEPROM in the device be reprogrammed?

     
    Just to be clear, we need to running from a power-on in about 500ms",  Thanks again.
  • 0 in reply to Paul Joseph
    TI__Genius 15100 points

    None of the customers we worked with wanted an internal RC and hence we didnt program it that way.

    EEPROM can be reprogrammed but this cannot be done by the customers. Its too complex to go to test mode and then use an external FPGA to program the new code.