Instruction Manual
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 VOUT_MODE.
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 VOUT_COMMAND and