In the datasheet for the max77958 it states:
"Default sink PDOs: 5V/3A, 9V/3A, and 15V/3A. If there are multiple source PDOs matching to the MAX77958 sink PDO list, the MAX77958 requests the highest power of PDO."
I'm trying to limit the requested voltage in the SNK PDOs to 5V (i.e. remove the 9V and 15V PDOs that are the default since my circuit can only handle up to 5V on Vbus. The only way I can find to change this is via the Op Code commmand 0x3F (SNK PDO Set) shown in the user guide
My issue is that I have no idea what the reset or default values for the AP_DATAOUT1-32 (aka ADDR 0x22 - 41) should be as there are no RESET values provided. Is there any reference for what values these should take? In other words, how can I take a design parameter like having a SNK PDO of 5V/3A and convert that to the appropriate binary/hex values to populate these Op Code commands?
I just had a look through the RTOS firmware provided by Maxim and it looks like they are writing the
snkPDOVoltage_L within an array passed to the
0x56 Customer Configuration Write OpCode command. See
max77958_driver.c lines 694-695.
customer_info.custm_bits.snkPDOVoltage_H = 0x64; /* 5000mV */
customer_info.custm_bits.snkPDOVoltage_L = 0x64; /* 5000mV */
This seems to be in conflict with what is stated in the user guide
As the guide only specifies ADDR up to 0x38, and the firmware shows bits following the SID4 ADDR. This would imply that the opcode-command-guide is out of date or the firmware is just radically wrong. Hopefully the guide is outdated and I can simply update the SNK PDO voltages using the 0x56 Customer Configuration Write Opcode as is exemplified with the RTOS firmware.