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Maxim Integrated Products, Inc.

VT1697SB

Theory of Operation

The slaves include protection circuits that shut down the slave

operating range. If either of these circuits is tripped during

operation, the slave will stop switching and a fault signal

(TS_FAULTB pulled LOW) will be sent to the master.

Temperature Sensing and Overtemperature

Protection

Each smart slave IC incorporates an accurate die tempera-

ture sensor. The temperature sense signal is sent to the mas-

ter as an analog signal via the temperature sense pin. The

actual temperature of each smart slave device is then made

available via the SMBus of the master. The smart slave IC

also includes overtemperature protection. If the trip point is

reached, the IC immediately shuts down and the fault is

reported to the master via the TS_FAULTB pin.

VX Short Protection

The smart slave ICs include a VX short detection to detect a

If such a fault is detected, the slave shuts down and commu-

nicates a fault to the master via the TS_FAULTB pin.

TS_FAULTB Signal

If a fault is detected, the smart slave sends a signal to the

master by pulling the TS_FAULTB pin to ground. Under nor-

mal conditions, this pin is used to send an accurate analog

representation of the slave temperature. If a fault is detected,

this pin is asserted LOW to indicate that a fault condition was

detected by a slave IC. Table 1 shows the faults that result in

this signal being asserted. For a latching fault, the fault must

non-latching faults, see note below the Table 1.). Please refer

to the applicable master IC data sheet for details about han-

Table 1: Fault Detection and Protection Circuits

Fault

Description

Type

Fault Flag (TS_FAULTB)

Boost UVLO

Undervoltage Lockout on Boost Supply

Shutdown*

Asserted

Shutdown*

Asserted

Shutdown*

Asserted

Shutdown*

Asserted

Shutdown

Asserted

POCP (Sourcing)

Positive/Sourcing Overcurrent Protection

Cycle-by-Cycle Current Limit

Not Asserted

NOCP (Sinking)

Negative/Sinking Overcurrent Protection

Cycle-by-Cycle Current Limit

Not Asserted

OTP

Overtemperature Protection

Shutdown

Asserted

*

VDDH_UVLO, VDDH_OVLO, VBST_UVLO and VDD_UVLO are non-latching faults. If a non-latching fault is detected by the slave, it will assert TS_FAULTB

signal low and stop switching. The slave resumes switching and de-asserts TS_FAULTB around 37µs from when the fault condition is removed. Please refer

to the master data sheet for master response to TS_FAULTB asserted LOW by the slave device.