Datasheet

LTC2977
45
2977fa
For more information www.linear.com/LTC2977
MANUFACTURER SPECIFIC COMMANDS
MFR_CONFIG_LTC2977
This command is used to configure various manufacturer specific operating parameters for each channel.
MFR_CONFIG_LT C 2977 Data Contents
BIT(S) SYMBOL OPERATION
b[15:14] Mfr_config_chan_mode Select channel specific sequencing mode.
00 = Channel uses PMBus delay sequencing with immediate off upon fault.
01 = Channel uses PMBus delay sequencing with sequence off upon fault.
1x = Channel is a slave in a tracked power supply system.
b[13:12] Reserved Don’t care. Always returns 0.
b[11] Mfr_config_fast_servo_off Disables fast servo when margining or trimming output voltages:
0: fast-servo enabled.
1: fast-servo disabled.
b[10] Mfr_config_supervisor_resolution Selects supervisor resolution:
0: high resolution = 4mV/LSB, range for V
VSENSEPn
– V
VSENSEMn
is 0V to 3.8V.
1: low resolution = 8mV/LSB, range for V
VSENSEPn
– V
VSENSEMn
is 0V to 6.0V.
b[9] Mfr_config_adc_hires Selects ADC resolution for odd channels. This is typically used to measure current. Ignored for even
channels (they always use low resolution).
0: low resolution = 122µV/LSB.
1: high resolution = 15.6µV/LSB.
b[8] Mfr_config_controln_sel Selects the active control pin input (CONTROL0 or CONTROL1) for this channel.
0: Select CONTROL0 pin.
1: Select CONTROL1 pin.
b[7] Mfr_config_servo_continuous Select whether the UNIT should continuously servo V
OUT
after it has reached a new margin or nominal
target. Only applies when Mfr_config_dac_mode = 00b.
0: Do not continuously ser
vo V
OUT
after reaching initial target.
1: Continuously servo V
OUT
to target.
b[6] Mfr_config_servo_on_warn Control re-servo on warning feature. Only applies when Mfr_config_dac_mode = 00b and
Mfr_config_servo_continuous = 0.
0: Do not allow the unit to re-ser
vo when a V
OUT
warning threshold is met or exceeded.
1: Allow the unit to re-servo V
OUT
to nominal target if
V
OUT
≥ V(Vout_ov_warn_limit) or
V
OUT
≤ V(Vout_uv_warn_limit).
b[5:4] Mfr_config_dac_mode Determines how DAC is used when channel is in the ON state and TON_RISE has elapsed.
00: Soft-connect (if needed) and servo to target.
01: DAC not connected.
10: DAC connected immediately using value from MFR_DAC command. If this is the configuration after a
reset or RESTORE_USER_ALL, MFR_DAC will be undefined and must be written to desired value.
11: DAC is soft-connected. After soft-connect is complete MFR_DAC may be written.
b[3] Mfr_config_vo_en_wpu_en V
OUT_EN
pin charge-pumped, current-limited pull-up enable.
0: Disable weak pull-up. V
OUT_EN
pin driver is three-stated when channel is on.
1: Use weak current-limited pull-up on V
OUT_EN
pin when the channel is on.
For channels 4-7 this bit is treated as a 0 regardless of its value.
b[2] Mfr_config_vo_en_wpd_en V
OUT_EN
pin current-limited pull-down enable.
0: Use a fast N-channel device to pull down V
OUT_EN
pin when the channel is off for any reason.
1: Use weak current-limited pull-down to discharge V
OUT_EN
pin when channel is off due to soft stop by the
CONTROLn pin and/or OPERATION command. If the channel is off due to a fault, use the fast pull-down on
V
OUT_EN
pin.
For channels 4-7 this bit is treated as a 0 regardless of its value.
PMBus COMMAND DESCRIPTION