Datasheet

LTC3880/LTC3880-1
66
3880fc
For more information www.linear.com/LTC3880
ON/OFF/MARGIN
COMMAND NAME
CMD
CODE DESCRIPTION TYPE PAGED
DATA
FORMAT UNITS NVM
DEFAULT
VALUE
ON_OFF_CONFIG 0x02 RUN pin and PMBus bus on/off command configuration. R/W Byte Y Reg Y 0x1E
OPERATION 0x01 Operating mode control. On/off, margin high and margin
low.
R/W Byte Y Reg Y 0x80
MFR_RESET 0xFD Commanded reset without requiring a power-down. Send Byte N NA
ON_OFF_CONFIG
The ON_OFF_CONFIG command configures the combination of RUNn pin input and serial bus commands needed to
turn the unit on and off. This includes how the unit responds when power is applied.
The only bits allowed to be changed are as follows:
3: Controls how the unit responds to commands received via the serial bus
0: RUN pin action when commanding the unit to turn off. If bit 0 is set to one, the part will stop transferring power to
the output stage as fast as possible. This will have the effect of the load discharging the output capacitor. Setting
bit 0 to a zero will cause the regulator to use the programmed turn-off delay and fall times. If the part is in continu
-
ous mode, the programmed turn-off response may pull the output to zero volts considerably faster than removing
power immediately from the load.
Changing the value of bits 4, 2 or 1, will generate a CML fault.
This command has one data byte.
Table 3. ON_OFF_CONFIG Detailed Register Information
ON_OFF_CONFIG Data Contents
BITS(S) SYMBOL OPERATION
b[7:5] Reserved Don’t care. Always returns 0.
b[3] On_off_config_use_pmbus Controls how the unit responds to commands received via the serial bus.
0: Unit ignores the Operation command b[7:6].
1: Unit responds to Operation command b[7:6]. The unit also requires the RUNn pin to be asserted for the
unit to start.
b[0] On_off_config_control_fast_off RUNn pin turn off action when commanding the unit to turn off.
0: Use the programmed TOFF_DELAY.
1: Turn off the output and stop transferring energy as quickly as possible. The device does not sink current
in order to decrease the output voltage fall time.
Note: A high on the RUN pin is always required to start power conversion. Power conversion will always stop with a low on RUN.
PMBus COMMAND DETAILS