LT7182S

19

Rev. 0

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OPERATION

PGOOD Pins

The open-drain PGOOD pins are each pulled low if the

corresponding channel is off for any reason, during

soft-start and soft-stop, or if the output voltage is below

VOUT_UV_FAULT_LIMIT.

ALERT Pin

The SMBALERT_MASK command configures which

warning and fault indicators cause the LT7182S to pull

down the open-drain ALERT pin.

Once the LT7182S pulls down the ALERT pin, the device

will continue to hold the pin low until one of the following

occurs:

• The faulted channel is disabled then re-enabled

• A CLEAR_FAULTS, RESTORE_USER_ALL or MFR_

RESET command is received

• All unmasked status bits are cleared by writing a 1 to

each bit

• The LT7182S successfully transmits its address during

a PMBus ARA

Fault Event Logging

If a fault condition occurs that is configured to turn off

the regulator output, an event is written in the fault log

in EEPROM. Any preceeding warning or fault that is not

configured to turn off the output is written as a sub-

event when an event is written. A timestamp is written

with each event and subevent. The fault log stores up

to three fault-off events. The fault log may be read by

the MFR_FAULT_LOG command. The fault log is cleared

from EEPROM by writing the MFR_FAULT_LOG_CLEAR

command. The fault log function is enabled by default and

may be disabled by clearing bit 7 of MFR_CONFIG_ALL.

See the MFR_FAULT_LOG command in the LT7182S

Table 1. Factory-Default Warning and Fault Behavior (Note 1)

WARNING OR FAULT TYPE

DETECTION METHOD

DEFAULT THRESHOLD

DEFAULT REGULATOR

RESPONSE

DEFAULT PIN RESPONSE

PGOOD

FAULT

ALERT

Comparator

VOUT_COMMAND –6.5%

Continue Operation

Pull Low

Comparator

VOUT_COMMAND +7.5%

Continue Operation

Pull Low

Comparator

VOUT_COMMAND –7%

Continue Operation

Pull Low

Pull Low

Comparator

VOUT_COMMAND +10%

Shutdown and Retry

Pull Low Pull Low Pull Low

Comparator

23.3V

Shutdown and Retry

Pull Low Pull Low Pull Low

ADC

–1.0V (Disabled)

Continue Operation

Pull Low

Overtemperature (OT) Warning

ADC

140°C

Continue Operation

Pull Low

OT Fault

ADC

160°C

Shutdown and Retry

Pull Low Pull Low Pull Low

ADC

Continue Operation

Pull Low

Valley Comparator

Continue Operation

Comparator and Timer

5ms without Exceeding

VOUT_UV_FAULT_LIMIT

Continue Operation

Pull Low

Pull Low

ADC and Timer

0 (Disabled)

N/A

Pin Configuration Error (Note 3)

I/O

N/A

Lock Off Until Next Reset Pull Low Pull Low Pull Low

EEPROM Error

CRC, ECC

N/A

Lock Off Until Next Reset Pull Low

Pull Low

Internal Reference Fault

ADC and 2nd Reference

±5%

Shutdown and Retry

Pull Low Pull Low Pull Low

Logic

N/A

N/A

Pull Low

Note 2. The IOUT_OC_FAULT valley current threshold is controlled by MFR_PWM_MODE_LT7182S bits [10:9].

Note 3. When a pin configuration error is detected during initialization, the device pulls low the following pins: FAULT0, FAULT1, RUN0, RUN1, SHARE_CLK,

PGOOD0, PGOOD1, and ALERT.