RT8295BHGSP Richtek

RT8295B 2A, 23V, 1.2MHz Synchronous Step-Down Converter General Description Features zz z zz 1.5% High Accuracy Feedback Voltage The RT8295B is a high-efficiency, monolithic synchronous zz z zz 4.5V to 23V Input Voltage Range step-down DC/DC converter that can deliver up to 2A zz z zz 2A Output Current output current from a 4.5V to 23V input supply. The zz z zz Integrated N-MOSFET Switches RT8295B s current mode architecture and external zz z zz Current Mode Control compensation allow the transient response to be zz z zz Fixed Frequency Operation : 1.2MHz optimized over a wide range of loads and output capacitors. zz z zz Adjustable Output from 0.8V to 15V Cycle-by-cycle current limit provides protection against zz z zz Up to 95% Efficiency shorted outputs and soft-start eliminates input current zz z zz Programmable Soft-Start surge during start-up. The RT8295B also provides under zz z zz Stable with Low-ESR Ceramic Output Capacitors voltage protection and thermal shutdown protection. The zz z zz Cycle-by-Cycle Over Current Protection low current (<3A) shutdown mode provides output zz z zz Input Under Voltage Lockout disconnection, enabling easy power management in zz z zz Output Under Voltage Protection battery-powered systems. The RT8295B is available in a zz z zz Thermal Shutdown Protection SOP-8 (Exposed Pad) package. zz z zz RoHS Compliant and Halogen Free Ordering Information Applications RT8295B Package Type z Wireless AP/Router SP : SOP-8 (Exposed Pad-Option 1) z Set-Top-Box Lead Plating System z Industrial and Commercial Low Power Systems G : Green (Halogen Free and Pb Free) z LCD Monitors and TVs Z : ECO (Ecological Element with z Green Electronics/Appliances Halogen Free and Pb free) z Point of Load Regulation of High-Performance DSPs H : UVP Hiccup L : UVP Latch-Off Pin Configurations Note : (TOP VIEW) Richtek products are : RoHS compliant and compatible with the current require- 8 BOOT SS ments of IPC/JEDEC J-STD-020. 2 7 VIN EN Suitable for use in SnPb or Pb-free soldering processes. GND 3 6 SW COMP 9 4 5 GND FB SOP-8 (Exposed Pad) Marking Information RT8295BxZSP RT8295BxGSP RT8295BxGSP : Product Number RT8295BxZSP : Product Number RT8295Bx RT8295Bx x : H or L x : H or L GSPYMDNN ZSPYMDNN YMDNN : Date Code YMDNN : Date Code DS8295B-03 March 2011 www.richtek.com 1RT8295B Typical Application Circuit 1 V 2 IN VIN BOOT 4.5V to 23V C C BOOT IN L RT8295B 10F 100nF 3.6H V 3 OUT SW 3.3V/2A R 100k EN R1 7 EN 75k C OUT 8 5 SS FB 22F x 2 C C C R SS C R2 0.82nF 32k 0.1F 4, 9 (Exposed Pad) 24k 6 GND COMP C P Open Table 1. Recommended Component Selection V (V) R1 (kW) R2 (kW) R (kW) C (nF) L (mH) C (mF) OUT C C OUT 8 27 3 75 0.82 10 22 x 2 5 62 11.8 47 0.82 6.8 22 x 2 3.3 75 24 32 0.82 3.6 22 x 2 2.5 25.5 12 25.5 0.82 3.6 22 x 2 1.5 10.5 12 15 0.82 2 22 x 2 1.2 12 24 12 0.82 2 22 x 2 1 3 12 10 0.82 2 22 x 2 Functional Pin Description Pin No. Pin Name Pin Function Bootstrap for High Side Gate Driver. Connect a 0.1F or greater ceramic 1 BOOT capacitor from BOOT to SW pins. Input Supply Voltage 4.5V to 23V. Must bypass with a suitably large ceramic 2 VIN capacitor. 3 SW Switch Node. Connect this pin to an external L-C filter. 4, Ground. The exposed pad must be soldered to a large PCB and connected to GND 9 (Exposed Pad) GND for maximum power dissipation. Feedback Input. This pin is connected to the converter output. It is used to set the output of the converter to regulate to the desired value via an internal 5 FB resistive voltage divider. For an adjustable output, an external resistive voltage divider is connected to this pin. Compensation Node. COMP is used to compensate the regulation control 6 COMP loop. Connect a series RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. Chip Enable (Active High). A logic-low forces the RT8295B into shutdown 7 EN mode reducing the supply current to less than 3A. Attach this pin to VIN with a 100k pull up resistor for automatic startup. Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor 8 SS from SS to GND to set the soft-start period. A 0.1F capacitor sets the soft-start period to 13.5ms. www.richtek.com DS8295B-03 March 2011 2