Datasheet

LTC2974
45
2974fc
For more information www.linear.com/LTC2974
pMbus coMManD DescripTion
VOUT_COMMAND, VOUT_MAX, VOUT_MARGIN_HIGH, VOUT_MARGIN_LOW, VOUT_OV_FAULT_LIMIT,
VOUT_OV_WARN_LIMIT, VOUT_UV_WARN_LIMIT, VOUT_UV_FAULT_LIMIT, POWER_GOOD_ON and
POWER_GOOD_OFF
These commands provide various ser
vo, margining and supervising limits for a channel’s output voltage.
MFR_VOUT_DISCHARGE_THRESHOLD
This register contains the coefficient that multiplies VOUT_COMMAND in order to determine the OFF threshold volt
-
age
for the associated output. If the output voltage has not decayed below MFR_VOUT_DISCHARGE_THRESHOLD •
VOUT_COMMAND prior to the channel being commanded to enter/re-enter the ON state, the Status_mfr_discharge bit
in the STATUS_MFR_SPECIFIC register will be set and the ALERTB pin will be asserted low
. In addition, the channel
will not enter the ON state until the output has decayed below its off-threshold voltage. Setting this to a value greater
than 1.0 effectively disables DISCHARGE_THRESHOLD checking, allowing the channel to turn back on even if it has
not decayed at all.
Other channels can be held-off if a particular output has failed to discharge by using the bidirectional FAULTBn pins
(refer to the MFR_FAULTBn_RESPONSE and MFR_FAULTBn_PROPOGATE registers).
MFR_DAC
This command register allows the user to directly program the 10-bit DAC. Manual DAC writes require the channel
to be in the ON state,TON_RISE to have expired and MFR_CONFIG_LTC2974 b[5:4] = 10b or 11b. Writing MFR_
CONFIG_LTC2974 b[5:4] = 10b commands the DAC to hard connect with the value in Mfr_dac_direct_val. Writing
b[5:4] = 11b commands the DAC to soft-connect. Once the DAC has soft-connected, Mfr_dac_direct_val returns the
value that allowed the DAC to be connected without perturbing the power supply. MFR_DAC writes are ignored when
MFR_CONFIG_LTC2974 b[5:4] = 00b or 01b.
MFR_DAC Data Contents
BIT(S) SYMBOL OPERATION
b[15:10] Reserved Read only, always returns 0.
b[9:0] Mfr_dac_direct_val DAC code value.