4.10 VSETx and VSETLx Resistor Decoder

The default start-up voltage for each power channel is configured using the VSETx/VSETLx pins. A resistor can either be connected from the pin to ground or short the pin to GND or SVIN. This provides 16 configuration options per channel:

• Pin shorted to GND: reserved to disable the corresponding power channel during the start-up sequence. The EN, SEQEN and RCON&REN bits are internally masked when the corresponding VSET[5:0] value is set to 0. To enable a channel that was disabled during the start-up phase, the user must program the corresponding VSET[5:0] register to the required output voltage, according to the selected mode of operation. For example, if the user changes only the VSET[5:0] value for Active mode, the channel will be enabled exclusively during Active mode. In the I2C Monitor graphical user interface, the VOUT associated with each operating mode will display “N/A” when the VSETx/VSETLx pin is shorted to ground. To enable this channel, the user should set VOUT to the desired value and then click Write Modified or Write All.
• All the other options: select 15 different start-up voltage levels (see the Configuring MCP16503 Default Start-Up Voltage Table from the Data Sheet).

The resistor values connected to the VSETx/VSETLx pins are decoded only once during the initialization phase. Specifically, after power is applied and the Finite State Machine (FSM) enters the INIT (Initialization) state (see Finite State Machine (FSM) States Diagram), the device begins decoding the resistor configuration.

When the decoding process is complete, the detected start-up voltage settings are stored in the VSET[5:0] fields of the OUTx-A and LDOx-A registers. These values are then copied to the corresponding VSET[5:0] fields in OUTx-LPM, OUTx-HIB, OUTx-HPM, LDOx-LPM, LDOx-HIB and LDOx-HPM. After this point, each channel's output voltage can be changed only via I²C (see Voltage Codes Definition Bits VSET[5:0] from the Data Sheet).