FAULT RESPONSE

UNDERVOLTAGE LOCKOUT (UVLO)

ENABLE (EN OR EN)

THERMAL SENSE

TPS2552

TPS2553, TPS2552-1, TPS2553-1

The FAULT open-drain output is asserted (active low) during an overcurrent, overtemperature or reverse-voltage

condition. The TPS2552/53 asserts the FAULT signal until the fault condition is removed and the device resumes

normal operation. The TPS2552-1/53-1 asserts the FAULT signal during a fault condition and remains asserted

while the part is latched-off. The FAULT signal is de-asserted once device power is cycled or the enable is

toggled and the device resumes normal operation. The TPS2552/53 and TPS2552-1/53-1 are designed to

eliminate false FAULT reporting by using an internal delay "deglitch" circuit for overcurrent (7.5-ms typ) and

reverse-voltage (4-ms typ) conditions without the need for external circuitry. This ensures that FAULT is not

accidentally asserted due to normal operation such as starting into a heavy capacitive load. The deglitch circuitry

delays entering and leaving fault conditions. Overtemperature conditions are not deglitched and assert the

FAULT signal immediately.

The undervoltage lockout (UVLO) circuit disables the power switch until the input voltage reaches the UVLO

turn-on threshold. Built-in hysteresis prevents unwanted on/off cycling due to input voltage drop from large

current surges.

The logic enable controls the power switch, bias for the charge pump, driver, and other circuits to reduce the

supply current. The supply current is reduced to less than 1-

µA when a logic high is present on EN or when a

logic low is present on EN. A logic low input on EN or a logic high input on EN enables the driver, control circuits,

and power switch. The enable input is compatible with both TTL and CMOS logic levels.

The TPS2552/53 and TPS2552-1/53-1 have self-protection features using two independent thermal sensing

circuits that monitor the operating temperature of the power switch and disable operation if the temperature

exceeds recommended operating conditions. The TPS2552/53 device operates in constant-current mode during

an overcurrent conditions, which increases the voltage drop across power-switch. The power dissipation in the

package is proportional to the voltage drop across the power switch, which increases the junction temperature

during an overcurrent condition. The first thermal sensor turns off the power switch when the die temperature

exceeds 135°C (min) and the part is in current limit. Hysteresis is built into the thermal sensor, and the switch

turns on after the device has cooled approximately 10 °C.

The TPS2552/53 and TPS2552-1/53-1 also have a second ambient thermal sensor. The ambient thermal sensor

turns off the power-switch when the die temperature exceeds 155°C (min) regardless of whether the power

switch is in current limit and will turn on the power switch after the device has cooled approximately 10 °C. Both

the TPS2552/53 and TPS2552-1/53-1 families continue to cycle off and on until the fault is removed.

The open-drain fault reporting output FAULT is asserted (active low) immediately during an overtemperature

shutdown condition.

12

Submit Documentation Feedback

Copyright © 2008–2009, Texas Instruments Incorporated

Product Folder Link(s): TPS2552 TPS2553 TPS2552-1 TPS2553-1