ACT4455 Active-Semi Product Brief, 28-Jun-11 36V/5A Step Down DC/DC Converter FEATURES APPLICATIONS • • • • • • • Wide 7.5V to 36V Operating Input Range • Automotive Industry 5A Continuous Output Current • Digital Set Top Boxes Integrated 45mΩ High-Side Power MOSFET • LCD-TV Output Adjustable from 0.8V to 28V • Broadband Communications 90% Efficiency at 5V/3A Output Switching Frequency 230kHz GENERAL DESCRIPTION Stable with Low ESR Ceramic Output Capacitors ACT4455 is a wide input voltage step-down DC/DC converter with high-side MOSFET integrated. It provides up to 5A continuous output current with optional dual over current protection for dual outputs. It runs at 230kHz switching frequency and achieves high efficiency and excellent load and line regulation. The protection features includes Cycleby-Cycle current limit, UVP and thermal shutdown. The device is available in SOP-8EP package. • 3ms Internal Soft Start • Low Standby Input Current • Internal Cycle-by-Cycle Over Current Protection • Input Under Voltage Lockout • Dual OCP Setting for Dual Outputs with External Current Sensing Resistors • Under Voltage at Over Current • Auto Restart at Output Over Current or Short Circuit • Frequency Foldback with Output Voltage • SOP-8EP Package TYPICAL APPLICATION CIRCUITS a: Dual Outputs with individual OCP Innovative PowerTM -1- Active-Semi Confidential―Do Not Copy or Distribute ActiveSwitcherTM is a trademark of Active-Semi. www.active-semi.com Copyright © 2011 Active-Semi, Inc. ACT4455 Product Brief, 28-Jun-11 7.5V to 36V C4 HSB VIN L1 3.3V/5A VOUT SW IN ACT4455 COMP GND CS1 R1 FB CS2 R3 C1 R2 C3 D1 C2 GND b: Single Output with Cycle-by-Cycle Current Limit PIN CONFIGURATION PIN DESCRIPTIONS PIN NAME DESCRIPTION 1 CS1 The output current of VOUT1 is sensed by this pin. When the voltage on this pin reaches 115mV for 150µs, the IC shuts down for 3 seconds and then restarts. 2 SW Switch Output. Connect this pin to the switching end of the external inductor. Note that a 22nF to 100nF capacitor is required from SW to HSB power the high-side switch. 3 HSB Bootstrap Input. This pin acts as the positive rail for the high-side switch’s gate driver. Connect a 22nF or greater capacitor between HSB and SW pins. 4 GND Ground. 5 COMP 6 FB Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive voltage divider from the output voltage. The feedback threshold is 0.8V. See Setting the Ouput Voltage. 7 IN Input Supply. Bypass this pin to GND with a low ESR capacitor. Drive IN with a 7.5V to 36V power source. 8 CS2 EP Innovative Power Compensation Node. COMP is used to compensate the regulation control loop. The output current of VOUT2 is sensed by this pin. When the voltage on this pin reaches 115mV for 150µs, the IC shuts down for 2.5 seconds and then restarts. Exposed Pad. Connect this pad to thick copper plane. TM -2- Active-Semi Confidential―Do Not Copy or Distribute ActiveSwitcherTM is a trademark of Active-Semi. www.active-semi.com Copyright © 2011 Active-Semi, Inc.