Features Wide 3.6V to 32V Input Voltage Range Output Adjustable from 0.8V to 30V Maximum Duty Cycle 100% Minimum Drop Out 0.6V Fixed 300KHz Switching Frequency 12A Constant Output Current Capability Internal Optimize Power MOSFET High efficiency Excellent line and load regulation Built in thermal shutdown function Built in current limit function Built in output short protection function Available in TO-220 package Applications LCD Monitor and LCD TV Digital Photo Frame Set-up Box ADSL Modem Telecom / Networking Equipment General Description The FS2012 is a 300 KHz fixed frequency PWM buck (step-down) DC/DC converter, capable of driving a 12A load with high efficiency, low ripple and excellent line and load regulation. Requiring a minimum number of external components, the regulator is simple to use and include internal Frequency compensation and a fixedfrequency oscillator. The PWM control circuit is able to adjust the duty ratio linearly from 0 to 100%. An over current protection function is built inside. When short protection function happens, the operation frequency will be reduced from 300KHz to 60KHz. An internal compensation block is built in to minimize external component count. Figure1. Package Type of FS2012 1
Pin Configurations Figure2. Pin Configuration of FS2012 (Top View) Table 1 Pin Description Pin Number Pin Name Description 1 GND 2 FB 3 SW Ground Pin. Care must be taken in layout. This pin should be placed outside of the Schottky Diode to output capacitor ground path to prevent switching current spikes from inducing voltage noise into FS2012. Feedback Pin (FB). Through an external resistor divider network, FB senses the output voltage and regulates it. The feedback threshold voltage is 0.8V. Power Switch Output Pin (SW). SW is the switch node that supplies power to the output. 4 NC No connected. 5 VIN Supply Voltage Input Pin. FS2012 operates from a 3.6V to 32V DC voltage. Bypass Vin to GND with a suitably large capacitor to eliminate noise on the input. 2
Function Block Figure3. Function Block Diagram of FS2012 Typical Application Circuit Figure4. FS2012 Typical Application Circuit 15V-5V/12A 3
Ordering Information Package Temperature Range Part Number Lead Free FS2012 Marking ID Lead Free FS2012 Packing Type Tube Absolute Maximum Ratings(Note1 Note1) Note1: Stresses greater than those listed under Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or anyother conditions above those indicated in the operation is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. 4
FS2012 Electrical Characteristics T a = 25 ;unless otherwise specified. Electrical Characteristics (DC Parameters) Vin = 12V, GND=0V, Vin & GND parallel connect a 220uf/50V capacitor; Iout=500mA, T a =25 ; the others floating unless otherwise specified. 5
Test Circuit and Layout guidelines Figure5. Standard Test Circuits and Layout Guides Select R1 to be approximately 2K, use a 1% resistor for best stability. C1 and CFF are optional; in order to increase stability and reduce the input power line noise, CIN and C1 must be placed near to VIN and GND; For output voltages greater than approximately 10V, an additional capacitor CFF is required. The compensation capacitor is typically between 100 pf and 33 nf, and is wired in parallel with the output voltage setting resistor, R2. It provides additional stability for high output voltage, low input-output voltages, and/or very low ESR output capacitors, such as solid tantalum capacitors. CFF=1/(31*1000*R2); This capacitor type can be ceramic, plastic, silver mica, etc. (Because of the unstable characteristics of ceramic capacitors made with Z5U material, they are not recommended.) 6
Schottky Diode Selection Table 7
Typical System Application for 24V ~ 12V/12A Version Figure6. FS2012 System Parameters Test Circuit (24V ~ 12V/12A) 8
Package Information TO220-5L 9