HIGH PRECISION PRECISION LOW POWER SWITCH

DESCRIPTION

USRB04 is a high performance, high precision and low cost

PWM Power switch for non-isolated buck and buck-boost

application. It combines a dedicated current mode PWM

controller with a high voltage power Bipolar in SOP8 package. Its

built-in error amplifier is optimized for good overshoot and

dynamic response for low cost and component count. With

precise inner resistor divider, precise reference of EA, constant

voltage regulation of 5.0V at universal AC input can be

guaranteed. Frequency reduction and burst mode control is

implemented for high efficiency at light load. Good EMI

performance is achieved with On-Bright proprietary frequency

shuffling technique and soft base driver design. Low startup

current and low operating current contribute to a reliable power

on startup and low standby power consumption with USRB04.

Constant power operation is supported at over load application

with USRB04, which makes it suitable for small home appliance

application where instant large power consumption is required

such as start-up of a fan.

USRB04 offers power on soft start control and protection

coverage with auto-recovery features including cycle-by-cycle

current limiting, output short circuit protection, FB pin open loop

protection, on-chip Over Temperature Protection (OTP), VDD

Over Voltage Protection (OVP) and VDD Under Voltage Lockout

Protection (UVLO). The tone energy at below 20KHz is minimized

in the design so that audio noise is eliminated during operation.

FEATURES

* Universal AC input range and 5.0V output voltage

* Constant power mode operation at over load application

* Low cost and less BOM for buck and buck-boost applications

* 40kHz (typical) maximum switching frequency

* Frequency shuffling for EMI improvement

* Power on soft-start

* Built-in Leading Edge Blanking(LEB)

* Cycle-by-cycle current limiting

* FB pin open loop protection

* Output short-circuit protection

* VDD Under Voltage Lockout with Hysteresis

* VDD OVP

* On-Chip OTP

* LED Lighting System