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AM5708: AM5708

Jeff Cohen
Prodigy 150 points
Part Number: AM5708
Other Parts Discussed in Thread: TPS65916

Good day,

I have an AM5709 system that is powered from the TPS659163 PMIC. The unit is in production but there are  yield issues.

The AM5708 boots from a USD card connected to MMC1. LDO1 of the TPS659163 is connected to the MMC1 supply on pins N8 and P8 of the AM5708. LDO1 is set to 3.3V Supply Voltage, but the USD Card is connected to another 3.3V supply that turns on 8ms after LDO1. The USD DATA, COMMAND and CARD_DETECT are pulled up with the LDO3 supply, before the USD card is powered. The other supply is turned on by the REGEN1 control output of the PMIC. 

1) Section 5.4.2.3 of the TPS65916 data sheet seems to indicate that it is recommended to power the SD card IO from LDO1 and LDO2, but what is the recommendation for the SD Card?

2)  Is there a reference design for AM5709 that uses the TPS659163 and boots from MMC1?  

3) How much time is allowed between MMC1 being powered up and the SD Card being powered? Is there a min/max specification?

Thank you for your help and support.

Jeff Cohen, Hubbell Utility Systems Boonton, NJ 07005

  • +1
    Prodigy 150 points

    According to section 3.4.1 of the SDA Physical Layer Specification, Version 3.01, power must be applied to the VDD pin before any I/O pin is set to logic HIGH. ​ In other words, CMD, CLK, and DAT0-3 must be at zero (0) volts when power is applied to the VDD pin. ​ This is to ensure proper initialization and prevent any unknown states in the device. Based on this it seems that the SD Card.

    I still do not know the timing of REGEN1 going active to the turning on of LDO1.

    Jeff Cohen