Analog Devices Linear LTM 4700 User Manual page 80

LTM4700
PMBus COMMAND DETAILS
ON_OFF_CONFIG
The ON_OFF_CONFIG command specifies the combination of RUNn pin input state and PMBus commands needed to
turn the PWM channel on and off.
Supported Values:
VALUE MEANING
0x1F OPERATION value and RUNn pin must both command the device to start/run. Device executes immediate off when commanded off.
0x1E OPERATION value and RUNn pin must both command the device to start/run. Device uses TOFF_ command values when commanded off.
0x17 RUNn pin control with immediate off when commanded off. OPERATION on/off control ignored.
0x16 RUNn pin control using TOFF_ command values when commanded off. OPERATION on/off control ignored.
Programming an unsupported ON_OFF_CONFIG value will generate a CML fault and the command will be ignored.
This command has one data byte.
OPERATION
The OPERATION command is used to turn the unit on and off in conjunction with the input from the RUNn pins. It
is also used to cause the unit to set the output voltage to the upper or lower MARGIN VOLTAGEs. The unit stays in
the commanded operating mode until a subsequent OPERATION command or change in the state of the RUNn pin
instructs the device to change to another mode. If the part is stored in the MARGIN_LOW/HIGH state, the next RESET
or POWER_ON cycle will ramp to that state. If the OPERATION command is modified, for example ON is changed
to MARGIN_LOW, the output will move at a fixed slope set by the VOUT_TRANSITION_RATE. The default operation
command is sequence off. If V
configuration pins are not installed, the outputs will be commanded off.
The part defaults to the Sequence Off state.
This command has one data byte.
Supported Values:
VALUE MEANING
0xA8 Margin high.
0x98 Margin low.
0x80 On (V back to nominal even if bit 3 of ON_OFF_CONFIG is not set).
OUT
0x40* Soft off (with sequencing).
0x00* Immediate off (no sequencing).
*Device does not respond to these commands if bit 3 of ON_OFF_CONFIG is not set.
Programming an unsupported OPERATION value will generate a CML fault and the command will be ignored.
This command has one data byte.
MFR_RESET
This command provides a means to reset the LTM4700 from the serial bus. This forces the LTM4700 to turn off both
PWM channels, load the operating memory from internal EEPROM, clear all faults and then perform a soft-start of
both PWM channels, if enabled.
This write-only command has no data bytes.
80
is applied to a part with factory default programming and the VOUT_CONFIG resistor
IN
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Rev. B