Output voltage-related commands, Vout_mode, Vout_command – Maxim Integrated MAX15303 PMBus Command Set User Manual
Page 9: Vout_trim
MAX15303 PMBus Command Set User’s Guide
Page 9 of 52
Output Voltage-Related Commands
VOUT_MODE
Reference:
Standard Command
Lockable:
No
Command Code:
0x20
Format:
Mixed: bit-field and two’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 MAX15303 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 MAX15303 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:
0x1334 (1.200V)
Description/Notes: See Section 8.2 of the PMBus Specification Part II.
VOUT_COMMAND mantissa data sent to and from the MAX15303 must be divided by 4096 to
determine the actual voltage value, according to the fixed value of
The factory value of 0x1334 (1.200V) 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 MAX15303, 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 MAX15303 IC 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 MAX15303, the value of VOUT_TRIM is summed with the value of