RT8289GSP Richtek

RT8289 5A, 32V, 500kHz Step-Down Converter General Description Features High Output Current up to 5A The RT8289 is a step-down regulator with an internal Power Internal Soft-Start MOSFET. It achieves 5A of continuous output current over 100m Internal Power MOSFET Switch a wide input supply range with excellent load and line Internal Compensation Minimizes External Parts regulation. Current mode operation provides fast transient Count response and eases loop stabilization. High Efficiency up to 90% The RT8289 provides protections such as cycle-by-cycle 25A Shutdown Current current limiting and thermal shutdown. In shutdown mode, Fixed 500kHz Frequency the regulator draws 25A of supply current. Thermal Shutdown Protection The RT8289 requires a minimum number of external Cycle-by-Cycle Over Current Protection components, to provide a compact solution. Wide 5.5V to 32V Operating Input Range Adjustable Output Voltage from 1.222V to 26V The RT8289 is available in a SOP-8 (Exposed Pad) Available in an SOP-8 (Exposed Pad) Package package. RoHS Compliant and Halogen Free Ordering Information RT8289 Applications Package Type Distributive Power Systems SP : SOP-8 (Exposed Pad-Option 1) LCD TV Lead Plating System DSL Modems G : Green (Halogen Free and Pb Free) Pre-regulator for Linear Regulators Note : Battery Charger Richtek products are : RoHS compliant and compatible with the current require- Pin Configurations ments of IPC/JEDEC J-STD-020. (TOP VIEW) Suitable for use in SnPb or Pb-free soldering processes. BOOT 8 SW 2 7 NC VIN Marking Information GND 3 6 NC GND RT8289GSP : Product Number 9 4 5 FB EN RT8289 YMDNN : Date Code GSPYMDNN SOP-8 (Exposed Pad) Typical Application Circuit V 7 1 IN BOOT VIN 5.5V to 32V C L C BOOT IN RT8289 10H 10nF 4.7F x 2 V 8 OUT SW 5V/5A Chip Enable 5 D EN R1 B550C 10k C OUT Open 4 47Fx2 = Automatic Startup 6, Exposed Pad (9) FB GND (POSCAP) R2 3.16k Copyright 2014 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8289-02 October 2014 www.richtek.com 1RT8289 Functional Pin Description Pin No. Pin Name Pin Function High Side Gate Drive Bootstrap Input. BOOT supplies the drive for the high side 1 BOOT N-MOSFET switch. Connect a 10nF or greater capacitor from SW to BOOT to power the high side switch. 2, 3 NC No Internal Connection. Feedback Input. FB senses the output voltage to regulate said voltage. Drive FB 4 FB with a resistive voltage divider from the output voltage. The value of the divider resistors also sets loop bandwidth. The feedback threshold is 1.222V. Chip Enable (Active High). EN is a digital input that turns the regulator on or off. 5 EN Drive EN higher than 1.4V to turn on the regulator, lower than 0.4V to turn it off. For automatic startup, leave EN unconnected. 6, Ground. The exposed pad must be soldered to a large PCB and connected to GND 9 (Exposed Pad) GND for maximum power dissipation. Power Input. VIN supplies the power to the IC, as well as the step-down 7 VIN converter switches. Drive V with a 5.5V to 32V power source. Bypass V to IN IN GND with a suitably large capacitor to eliminate noise on the input to the IC. Power Switching Output. SW is the switching node that supplies power to the 8 SW output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BOOT to power the high side switch. Function Block Diagram VIN Current Sense Ramp Amplifier - Generator + BOOT Oscillator Regulator S EN 500kHz Q Driver + R - Error Reference PWM SW Amplifier Comparator + FB - Bootstrap 12k OC Limit 30pF Control Clamp 400k GND 13pF Copyright 2014 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS8289-02 October 2014 2