Tool/software:
In my design, I have 5V and 3.3V power supply from LDOs. I do not need any supply from BQ76952, which is being used for voltage measurement and balancing only.
I am using BQ7695204PFBR version with default SPI and 5V on REG1.
I have shorted BREG and REGIN to ground and have left REG1 floating in my design.
I am not getting any signal of MISO line of IC. I have checked on oscilloscope. CS, MOSI and CLK signals are available and in good shape, but MISO signal is not coming.
From where does the SPI block gets its power supply? The voltage on REG18 is 1.8V
I know that my code is correct because in my previous version of design, I had connected 5V to BREG and REGIN and a capacitor to REGIN. Below is a snipped from the previous design in which the complete system was working.
I had changed the design because going through the datasheet I realized that 5V at REG1 (or any other value) may not be required as it was intended to power up other ICs on board. Since I already had LDOs for that, I removed the connections to simplify the design.
What is wrong with the new design as in the first figure? Does 1.8V internal voltage drive the SPI block of the IC or a voltage is required at REG1?
