Maxim Integrated MAX15301 PMBus Command Set - Manual (Page 10)

MAX15301 PMBus Command Set User’s Guide
Rev 1 Page 10 of 53
Output Voltage Related Commands
VOUT_MODE
Reference: Standard Command Lockable: No
Command Code: 0x20 Format: Mixed: bit-field and 2’s complement
Data Bytes: 1 Units: N/A
Transfer: Read Byte Factory Value: 0x14 (Linear Mode, exponent -12)
Description/Notes: See Section 8.2 of the PMBus Specification Part II.
The MAX15301 only supports Linear Mode values for output voltage related commands. The
VOUT_MODE command is read-only and the value cannot be changed.
The 5-bit exponent for output voltage data is -12, or two’s-complement 10100. This means that
voltage command data sent to and from the MAX15301 using either the 2-byte unsigned integer
mantissa or Direct mantissa formats must be divided by 4096 to determine the actual voltage value.
VOUT_COMMAND
Reference: Standard Command Lockable: Yes
Command Code: 0x21 Format: Unsigned integer mantissa
Data Bytes: 2 Units: V
Transfer: Read/Write Word Factory Value: 0x0001 (see Description)
Description/Notes: See Section 8.2 of the PMBus Specification Part II.
VOUT_COMMAND mantissa data sent to and from the MAX15301 must be divided by 4096 to
determine the actual voltage value, according to the fixed value of
VOUT_MODE .
The factory value of 0x0001 (0.244mV) will be overridden during initialization by the hardware (pin-
strap) value determined by the resistance to ground detected at the SET pin, unless a specific value
has been written to the User Store. The value of the SET pin resistance is measured only once during
initialization (power-up).
In the MAX15301, there are seven possible output voltage ranges based on seven corresponding
internal feedback divider taps. The value of VOUT_COMMAND is retained and read back from volatile
memory, regardless of limitations imposed by the feedback divider range.
New values of VOUT_COMMAND can be written at any time, but large changes (specifically, those
that require a different feedback divider selection;, see Table 7 of the MAX15301 data sheet) will
require the output to be disabled for the feedback divider to change.
VOUT_TRIM
Reference: Standard Command Lockable: Yes
Command Code: 0x22 Format: Linear
Data Bytes: 2 Units: V
Transfer: Read/Write Word Factory Value: 0x0000 (0V)
Description/Notes: See Section 13.3 of the PMBus Specification Part II.
In the MAX15301, the value of VOUT_TRIM is summed with the value of VOUT_COMMAND and