RT8110BGJ8

RT8110B Compact Wide Input Range Synchronous Buck DC/DC PWM Controller General Description Features zz z zz 10V to 28V Wide Input Voltage Range The RT8110B is a compact fixed-frequency PWM controller zz z zz 0.8V Internal Reference with integrated MOSFET drivers for single power rail zz z zz Internal Soft Start synchronous single-phase buck converter. This part zz z zz High DC Gain Voltage Mode PWM Control features an internal regulator that allows wide input voltage zz z zz Fixed 400kHz Switching Frequency range operation. The RT8110B utilizes voltage-mode zz z zz Fast Transient Response control with internal compensation to simplify the zz z zz Fully Dynamic 0 to 80% Duty Cycle converter design. An internal 0.8V reference voltage allows zz z zz Over Current Protection low output voltage application. The switching frequency zz z zz Under Voltage Protection is fixed at 400kHz to reduce the external passive zz z zz Over Temperature Protection component size to save board space. The RT8110B zz z zz Tiny Package TSOT-23-8 provides under voltage protection, current limit, over current zz z zz RoHS Compliant and Halogen Free protection and over temperature protection. The low-side MOSFET R is used to sense the inductor current DS(ON) Applications for over current protection. z Set-top Box Power Supplies Ordering Information z PC Subsystem Power Supplies RT8110B z Cable Modems, DSL Modems z DSP and Core Communication Processor Power Package Type J8 : TSOT-23-8 Supplies Lead Plating System z Memory Power Supplies G : Green (Halogen Free and Pb Free) z Personal Computer Peripherals Note : z Industrial Power Supplies Richtek products are : z Low Voltage Distributed Power Supplies RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Pin Configurations Suitable for use in SnPb or Pb-free soldering processes. (TOP VIEW) Marking Information For marking information, contact our sales representative 8 7 6 5 directly or through a Richtek distributor located in your 2 34 area. TSOT-23-8 DS8110B-02 April 2011 www.richtek.com 1 VCC FB LGATE VIN GND PHASE UGATE BOOT+ + V IN C2 C C4 IN D RT8110B C BOOT 1 5 VCC BOOT C1 4 UGATE Q1 L 6 7 PHASE V OUT VIN C5 R3 C3 2 C OUT LGATE Q2 3 8 FB GND R1 R2 RT8110B Typical Application Circuit Functional Pin Description Pin No. Pin Name Pin Function Internal regulator output pin, typically 5.5V. VIN is regulated to VCC by the internal regulator. VCC is the main bias supply of the IC. This pin also provides power for the low 1 VCC side MOSFET gate driver. Connect a ceramic capacitor to this pin. The voltage at this pin is monitored for power on reset (POR). 2 LGATE Gate Drive Pin for Low-Side MOSFET. Signal and Power Ground of the IC. All voltage levels are referenced with respect to this 3 GND pin. 4 UGATE Gate Drive Pin for High Side MOSFET. This pin provides power to the high-side MOSFET gate driver. A bootstrap circuit is used 5 BOOT to drive the high side MOSFET. Switching Node of the Buck Converter. This pin is also used to monitor the voltage drop 6 PHASE across the low side MOSFET for over current protection. This pin is internally connected to the collector of integrated BJT, which is designed to 7 VIN withstand 28V to provide a regulated 5.5V voltage to VCC pin. Inverting Input of the Error Amplifier. This pin is connected to the joint of output voltage 8 FB divider resistors to set the output voltage. The voltage at this pin is also monitored for under voltage protection. www.richtek.com DS8110B-02 April 2011 2