RT8295AHZSP Richtek

RT8295A 2A, 23V, 340kHz Synchronous Step-Down Converter General Description Features zz z zz 1.5% High Accuracy Feedback Voltage The RT8295A 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 RT8295A 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 : 340kHz optimized over a wide range of loads and output capacitors. zz z zz Adjustable Output from 0.8V to 20V 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 RT8295A also provides under zz z zz Stable with Low-ESR Ceramic Output Capacitors voltage protection and thermal shutdown prptection. 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 RT8295A 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 RT8295A 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 2 ments of IPC/JEDEC J-STD-020. 7 VIN EN GND 3 6 SW COMP Suitable for use in SnPb or Pb-free soldering processes. 9 4 5 GND FB SOP-8 (Exposed Pad) Marking Information RT8295AxZSP RT8295AxGSP RT8295AxZSP : Product Number RT8295AxGSP : Product Number RT8295Ax x : H or L RT8295Ax x : H or L ZSPYMDNN GSPYMDNN YMDNN : Date Code YMDNN : Date Code DS8295A-03 March 2011 www.richtek.com 1RT8295A Typical Application Circuit 1 V 2 IN VIN BOOT 4.5V to 23V C C BOOT IN L RT8295A 10F 100nF 10H 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 3.3nF 13k 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 27 3.3 22 22 x 2 5 62 11.8 20 3.3 15 22 x 2 3.3 75 24 13 3.3 10 22 x 2 2.5 25.5 12 9.1 3.3 6.8 22 x 2 1.5 10.5 12 4.7 3.3 3.6 22 x 2 1.2 12 24 3.6 3.3 3.6 22 x 2 1 3 12 3 3.3 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 Phase 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 high enables the converter a logic low forces the RT8295A into shutdown mode reducing the supply current to less 7 EN 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 DS8295A-03 March 2011 2