FAN8303

FAN8303 — 2A 23V Non-Synchronous Step-Down DC/DC Regulator December 2008 FAN8303 2A 23V Non-Synchronous Step-Down DC/DC Regulator Features 2A Output Current 0.22Ω Internal Power MOSFET Switch W ide 5V to 23V Operating Input Range Output Adjustable from 0.6 to 20V Stable with Low ESR Output Ceramic Capacitors Up to 90% Efficiency Less than 40µA Shutdown Current Fixed 370kHz Frequency Thermal Shutdown with Hysteresis Cycle-by-Cycle Over-Current Protection Available in 8-Pin SOIC Package Description The FAN8303 is a monolithic, non-synchronous, stepdown (buck) regulator with internal power MOSFETs. It achieves 2A continuous output current over a wide input supply range with excellent load and line regulation. Current-mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. The regulator draws less than 40µA shutdown current. FAN8303 requires a minimum number of readily available standard external components. External compensation, enable, and programmable soft-start features allow design optimization and flexibility. Cycle-by-cycle current limit, frequency foldback, and thermal shutdown provide protection against shorted outputs. CBS 10 nF Applications Set-Top Box DSL and Cable Modems Distributed Power Systems Consumer Appliances (DVD) Auxiliary supplies INPUT 5~23V C IN 10 µF VIN ENABLE SHUTDOWN EN BS SW L1 15 µ H OUTPUT 2.5V/2A D1 FAN8303 SS GND CSS 10 nF FB COMP R2 18 k R3 RC 22 k 5.6 k COU T 22 µF CA OPEN CC 1nF Figure 1. Typical Application Ordering Information Part Number FAN8303MX Eco Status RoHS Operating Temperature Range -40°C to +85°C Package 8-SOIC Packing Method Reel For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html. © 2008 Fairchild Semiconductor Corporation FAN8303 • Rev. 1.0.0 www.fairchildsemi.com FAN8303 — 2A 23V Non-Synchronous Step-Down DC/DC Regulator Internal Block Diagram Figure 2. Functional Block Diagram © 2008 Fairchild Semiconductor Corporation FAN8303 • Rev. 1.0.0 www.fairchildsemi.com 2 FAN8303 — 2A 23V Non-Synchronous Step-Down DC/DC Regulator Pin Configuration BS VIN SW GND Figure 3. SS EN COMP FB Pin Configuration (Top View) Pin Definitions Name BS VIN SW Pin # 1 2 3 Type Bootstrap Supply Voltage Switch Description High-Side Drive BOOT Voltage. Connect through capacitor (CBS) to SW. The IC includes an internal synchronous bootstrap diode to recharge the capacitor on this pin to VCC when SW is LOW. Power Input. This pin needs to be closely decoupled to the GND pin with a 10µF or greater ceramic capacitor. Power Switching Output. SW is the switching node that supplies power to the output. Power Return and Signal Ground for the IC. All internal control voltages are referred to this pin. Tie this pin to the ground island / plane through the lowest impedance connection. This pin is the ground reference for the regulated output voltage. Feedback Input. This pin is the center tap of the external feedback voltage resistive divider across the output. Compensation Node. Frequency compensation is accomplished at this node by connecting a series R-C to ground. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN HIGH to turn on the regulator, drive it LOW to turn it off. For automatic startup, leave EN unconnected. External Soft-Start. A capacitor connected between this pin and GND can be used to set soft-start time. GND 4 Ground FB COMP EN SS 5 6 7 8 Feedback Compensation Enable Soft Start © 2008 Fairchild Semiconductor Corporation FAN8303 • Rev. 1.0.0 www.fairchildsemi.com 3 FAN8303 — 2A 23V Non-Synchronous Step-Down DC/DC Regulator Absolute Maximum Ratings Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. All voltage values, except differential voltages, are given with respect to the network ground terminal. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device Symbol VIN VSW VBS VFB VEN VCOMP VSS ΘJA ΘJC TJ TL TSTG ESD Supply Voltage, VIN to GND Switch Voltage, SW to GND Boost Voltage Feedback Voltage Enable Voltage Compensation Voltage Soft-Start Voltage Parameter Min. -0.3 -0.3 -0.3 -0.3 -0.3 Max. 25 VIN+0.3 VSW + 6 6.0 6.0 6.0 6.0 105 40 Unit V V V V V V V °C/W °C/W °C °C °C kV Thermal Resistance, Junction-Air Thermal Resistance, Junction-Case Operating Junction Temperature Lead Temperature (Soldering, 5 Seconds) Storage Temperature Range Human Body Model, JEDEC JESD22-A114 Electrostatic Discharge Charged Device Model, JEDEC JESD22Protection Level C101 -65 3.0 2.5 -40 +125 +260 +150 Recommended Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to absolute maximum ratings. Symbol VIN TA Supply Voltage Parameter Operating Ambient Temperature Min 5 -40 Max. 23 +85 Unit V °C © 2008 Fairchild Semiconductor Corporation FAN8303 • Rev. 1.0.0 www.fairchildsemi.com 4 FAN8303 — 2A 23V Non-Synchronous Step-Down DC/DC Regulator Electrical Characteristics VIN=12V, TA= -40 to +85°C, unless otherwise noted. Symbol VFB RON_H RON_L ILKG IPK fOSC VUVLO fSHORT DMAX TON_MIN VEN VEN_H IOFF IQ GCS GEA AVEA ISS TSD Parameter Feedback Voltage Upper Switch On Resistance Lower Switch On Resistance Upper Switch Leakage Current Peak Inductor Current Oscillator Frequency Under-Voltage Lockout Short Circuit Frequency Maximum Duty Cycle Minimum On Time Enable Threshold Enable Threshold Hysteresis Supply Current (Shutdown) Supply Current (Quiescent) Current Sense Gain Error Amplifier Transconductance Error Amplifier Voltage Gain Soft-Start Current Thermal Shutdown Temperature Condition 25°C, 5V