Hello,
If none of the BQ7694201's internal LDOs (REG1, REG2) are configured. Does the SPI bus use REG18?
If so, is it push-pull or open drain configuration for the MISO pin.
Alternatively can REG1 be externally powered from an external regulator to force SPI to use REG1.
I am interfacing the BQ7694201 via SPI to an STM32 and am deciding whether I need a level shifter or I can get away with direct connections.
Cheers,
K
Hello Keshav,
The BQ7694201 uses REG1 LDO for SPI. However, LDOs are OFF by default. 
Alternatively can REG1 be externally powered from an external regulator to force SPI to use REG1.
Yes, but let me explain. The regulators REG1 and REG2 are fed from the REGIN pin. The REGIN pin can be externally powered. Simply ensure that a steady voltage of at least 5.5V is supplied to the REGIN pin.
Another alternative is to use the integrated regulator (REG0) which drives the base of an external NPN BJT (using the BREG pin) to provide the 5.5 V REGIN pin voltage. This is what our Evaluation Module Board uses.
More details are explained in Section 6.3.1 Preregulator Control of the Technical Reference Manual (TRM)
I don't think a level shifter is needed. You can configure the REG1 to 3.3V and connect MISO pin to REG1 (if not already connected)
Regards,
Jose Couso
