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TPS65216: Power output cycall by cycall

user4237065
Prodigy 20 points
Part Number: TPS65216
Other Parts Discussed in Thread: AM4377, , TLV62569

Project context

Use tps65216 to supply power to AM4377. The circuit diagram is as follows

problem description

Power output cycall by cycall: first LDO1\DCDC3\DCDC4 can be output to the set value, when DCDC1\DCDC2 output reaches the set value, all the power supply falls to 0V, and then repeat the above phenomenon in a 500ms cycle. The value of ENABLE1 Register is 0x3C read through the I2C interface, The results show that DCDC1\DCDC2 is not enabled.

  • 0
    TI__Mastermind 30260 points

    Do you have a scope shot showing all rails powering up, according to the power-up sequence in the TPS65216 datasheet? It is on page 25 in Figure 4-8. Typical Power-Up Sequence of the Main Output Rails

    I am unclear how the PMIC is starting the power-up sequence at all because your schematic shows AC_DET = 5V and there is no push-button connected to PB pin. When no push-button is present, AC_DET = GND will allow the PMIC to begin the power-up sequence.

    If you are reading 0x3C from I2C, it could be that you are reading the status of this register before DCDC1/2 are enabled. If the device has a fault on a DCDCx or LDO1 rail, the ENABLE register would typically toggle between 0x00 and 0x3F, but it would be very difficult to read 0x3C without lucky timing.

  • 0 in reply to Brian Berner
    Prodigy 20 points

    HI Brian

    Our product is not portable, we try to connect AC_DET to the ground, but the problem is still the same.Our system is composed of FPGA+AM377. FPGA is powered by TLV62569PDDC, ARM4377 is powered by TPS65216, and FPGA is controlled by PGOOD enable of TPS65216 to enable FPGA to  after ARM powe rup.During the experiment, we found that the system worked normally when the PGOOD was removed and the FPGA and ARM were started independently.

    Thanks & Best Regards,

    LI

  • 0 in reply to user4237065
    TI__Mastermind 30260 points

    Li,

    You are powering both FPGA AND AM4377 from the TPS65216 PMIC? 

    Have you considered that the FPGA is adding too much load to the system and the fault is due to over-current or low-voltage on one of the DCDCx or LDO1 rails?

    FPGA cannot be powered by TLV62569 alone. TLV62569 is a single-rail DC-DC converter and can only provide power to 1 rail of FPGA (core rail, maybe VCCINT). FPGAs will also require 1.8V, 3.3V, and sometimes other voltage rails.

    Unless the FPGA power is completely separated from AM4377 power, my conclusion is that one of the FPGA rails is over-loading the TPS65216 PMIC.