US3X77

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

5 of 10

www.unisonic.com.tw

QW-R502-568.B

FUNCTIONAL DESCRIPTION

OVERCURRENT PROTECTION

When the output load exceeds the current-limit threshold, The Over Current Protection will be triggered. The

typical current limit value of UTC US3077/US3277/US3377/US3477 is 1A, 1.5A, 2A, 2.5A. There is foldback of

current limit when short-circuit being encountered.

OC RESPONSE

The OC open-drain output is asserted (active low) when an over current or over-temperature shutdown condition

is encountered after a 9-ms deglitch timeout. The output remains asserted until the over-current or over-temperature

condition is removed.

THERMAL SHUTDOWN

Thermal shutdown protects UTC US3X77 from excessive power dissipation. If the die temperature exceeds 135°C,

the MOSFET switch is shut off. 20°C of hysteresis prevents the switch from turning on until the die temperature

drops to 115°C. Thermal shutdown circuit functions only when the switch is enabled.

UNDERVOLTAGE LOCKOUT (UVLO)

UVLO (under-voltage lockout) prevents the output MOSFET from turning on until IN (input voltage) exceeds 2.5V

typically. After the switch turns on, if the voltage drops below 2.3V typically, UVLO shuts off the output MOSFET.