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TPS65185: Schottky diodes or not

Markus Mayer53
Prodigy 80 points
Part Number: TPS65185
Other Parts Discussed in Thread: TPS65165

Hello,

while comparing the functional block diagram (Figure 20. of the TPS65165 datasheet of Feb 2017) with the reference design of the TPS65165EVM in slvu548 I noticed that in the datasheet the diodes connecting to VN and VB_SW seem to be Schottky diodes. Also Table 21 of the datasheet, section 9.2.2, two Schottky diodes are listed (BAS3010, MBR130T1). In the reference design of the TPS65165EVM all diodes are Schottky diodes MBR1301T. In my design I am using all BAS3010, and that doesn't seem to be working. Is it critical to have the MBR1301T diodes to VN and VB_SW?

More precisely, are Table 21 and Figure 20 to be understood in the sense that the diodes to VN and VB_SW should be one of the Schottky diodes (BAS3010, MBR130T1) and all other diodes (at or near VDDH_D and VEE_D) may be any of the three, i.e. either Schottky or the non-Schottky BAV99?

Thanks,

Markus

  • 0
    TI__Intellectual 810 points

    Hi Markus,

    I want to confirm that you in fact have your diodes tied to the proper pins, such that VN is tied to VN_SW and VB is tied to VB_SW? From what you indicated above it appears you may have connected VN to VB_SW. If possible, would you mind proving your schematic over email? The MBR1301T diode are not critical but are recommended due to their high reverse voltage, low forward voltage drop, and the peak current ratings. The MBR1301T and BAS3010 have similar performance.

    -Raymundo Hernandez-Toscano

  • 0
    TI__Intellectual 810 points
    Hi Markus,

    I received the schematic, thank you. In the schematic you sent I don't see the 100nF capacitors, did you mean the 10nF on the VDDH_DRV and VEE_DRV? Can you confirm through test point W11 that the PMIC is actually being supplied 3.3V? If so, can you communicate with the PMIC via I2C? Also, I noted that the input capacitance on VIN_P the inverting buck-boost(DCDC2) is about 4.7uF. To ensure that there is not a UVLO condition being triggered that forces a shutdown can you replace this with a larger capacitor, maybe 10uF or so?

    -Raymundo Hernandez-Toscano