SEMTECH SC1103

SC1103 Asynchronous Voltage Mode PWM Controller for 12V Input POWER MANAGEMENT Features Description The SC1103 is a versatile, low-cost, voltage-mode PWM ‹ Low cost / small size controller designed for 12V input DC/DC power supply ‹ Switch mode efficiency up to 95% applications. A simple, fixed-voltage buck regulator can ‹ 1% reference voltage accuracy be implemented using the SC1103 with a minimum of ‹ Over current protection external components. Internal level shift and drive ‹ 500mA output drive circuitry eliminates the need for an expensive p-channel, ‹ 5V to 12V Input power source high-side switch. The small device footprint ‹ Lead free package available. Fully WEEE and RoHS allows for compact circuit design. compliant SC1103 features include a temperature compensated Applications voltage reference, triangle wave oscillator, current limit comparator, frequency shift over-current protection, and ‹ Pentium® P55 Core Supply an internally compensated error amplifier. Pulse by pulse ‹ Low Cost Microprocessor Supplies current limiting is implemented by sensing the ‹ Peripheral Card Supplies differential voltage across an external resistor, or an ‹ Industrial Power Supplies appropriately sized PC board trace. ‹ High Density DC/DC Conversion The SC1103 operates at a fixed frequency of 200kHz, providing an optimum compromise between efficiency, external component size, and cost. Typical Application Circuit L1 R5 Vout = 2.5V @ 10A Q1 6uH 0.05 IRLR3103 + +12V R6 127*see note C11 C8 C9 C10 1.0 C1 220/4V 220/4V 220/4V C2 C3 D2 1.0 MBRD1035L R7 47/16V 47/16V 127 GND GND +20V R1 10 R2 R3 U1 1k 1k SC1103 C6 R4 0.01 2.2 1 8 VCC GND 2 7 CS(-) FB C4 C5 0.001 0.1 3 6 CS(+) BST C7 0.1 4 5 PGND DH * NOTE: R6 = R7 x (Vout/1.25 - 1) rounded to nearest 1%value 12V to 3.3V @ 10A with “flying capacitor” boost voltage. 1 Revision: July 28, 2005 www.semtech.com SC1103 POWER MANAGEMENT Absolute Maximum Ratings Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Pl arameter Sm ymbo Ms aximu Unit IV nput Voltage t4 o GND-V 0.3 to 1 CC GP round Differential t1 o GND ±V GND BD oost Input Voltage B6 ST to GN-V 0.3 to +2 OT perating Ambient Temperature Range 0C to +70 ° AMB ST torage Temperature Range -C 45 to +125 ° STG MT aximum Junction Temperature 1C 25 ° J LT ead Temperature (Soldering) 10 Sec. 3C 00 ° LEAD Thermal Resistance, Junction to Ambient θ 1W 65 °C/ JA Thermal Resistance, Junction to Case θ 4W 0 °C/ JC Electrical Characteristics V = 11.40V to 12.60V; GND = P = 0V; V = 2.5V; T = 25°C; BST = 22 ± 2V; CC GND O A Per test circuit, unless otherwise specified. Ps arameter Ss ymbol Cn ondition Mp i Tx y Ms a Unit RV eference 10 .23813 .25 1.26 REF V O5 ver 0 to 125°C Temp. range 10 .2215 .25 1.27 FI eedback Bias Current 20 .0 8A . µ FB QI uiescent Current Current into Vp0 in 50 . 8A . m Q CC LI oad Regulation =5 1A to 10A 00 . 1% . O LI ine Regulation =5 10A 0% . O C) urrent Limit Threshold C5 S(+) to CS (- 65758V m Oscillator Frequency 10 70 20 0 2z 3 kH OV scillator Frequency Shift < V/0 2 5z kH FB REF Max Duty Cycle 95 09% DI H Sink/Source Current V - V = 4.5V / (V - V=0 2V)5A 0 m O BST DH DH PGND UV VLO Threshold 3V .8 UVLO Note: (1) This device is ESD sensitive. Use of standard ESD handling precautions is required. www.semtech.com  2005 Semtech Corp. 2 SC1103 POWER MANAGEMENT Pin Configuration Ordering Information (1) De evice Packag Temp Range (T ) J Top View SC1103CS.TR SC O - 8 0° to 125° (2) SC1103CSTRT Notes: (1) Only available in tape and reel packaging. A reel contains 2500 devices. (2) Lead free product. This product is fully WEEE and RoHS compliant. (SO-8) Pin Descriptions Pe in # Pn in Nam Pin Functio 1CV. C Device Input Voltage 2)C. S(- Current Sense Input (Negative) 3)C. S(+ Current Sense Input (Positive) 4DP. GN Device power ground 5HD. High side driver output 6TBV S High side driver (Boost). BST 7BF. Error amplifier input (-) 8DG. N Signal ground Block Diagram  2005 Semtech Corp. 3 www.semtech.com SC1103 POWER MANAGEMENT Applications Information Layout Guidelines Careful attention to layout requirements are necessary 4) The Output Capacitor(s) (Cout) should be located as for successful implementation of the SC1103 PWM con- close to the load as possible, fast transient load cur- rents are supplied by Cout only, and connections between troller. High currents switching at 200kHz are present in Cout and the load must be short, wide copper areas to the application and their effect on ground plane voltage differentials must be understood and minimized. minimize inductance and resistance. 1). The high power parts of the circuit should be laid out 5) The SC1103 is best placed over an isolated ground plane area. GND and PGND should be returned to this first. A ground plane should be used, the number and isolated ground. This isolated ground area should be position of ground plane interruptions should be such as to not unnecessarily compromise ground plane integrity. connected to the main ground by a trace that runs from Isolated or semi-isolated areas of the ground plane may the GND pin to the ground side of (one of) the output be deliberately introduced to constrain ground currents capacitor(s). If this is not possible, the GND pin may be connected to the ground path between the Output to particular areas, for example the input capacitor and Capacitor(s) and the Cin, Q1, D1 loop. Under no circum- bottom Schottky ground. stances should GND be returned to a ground inside the 2). The loop formed by the Input Capacitor(s) (Cin), the Cin, Q1, D1 loop. Top FET (Q1) and the Schottky (D1) must be kept as small 6) Vcc for the SC1103 should be supplied from the VIN as possible. This loop contains all the high current, fast supply through a 10Ω resistor, the Vcc pin should be transition switching. Connections should be as wide and as short as possible to minimize loop inductance. Mini- decoupled directly to GND by a 0.1µF ceramic capacitor, mizing this loop area will reduce EMI, lower ground injec- trace lengths should be as short as possible. tion currents, resulting in electrically “cleaner” grounds 7) The Current Sense resistor and the divider across it for the rest of the system and minimize source ringing, should form as small a loop as possible, the traces run- resulting in more reliable gate switching signals. ning back to CS(+) and CS(-) on the SC1103 should run 3). The connection between the junction of Q1, D1 and parallel and close to each other. the output inductor should be a wide trace or copper 8) To minimize noise pickup at the sensitive FB pin, the feedback resistors should both be close to the SC1103 region. It should be as short as practical. Since this con- with the bottom resistor (Rb) returned to ground at the nection has fast voltage transitions, keeping this con- nection short will minimize EMI. The connection between GND pin. the output inductor and the sense resistor should be a wide trace or copper area, there are no fast voltage or Under Voltage Lockout current transitions in this connection and length is not The under voltage lockout circuit of the SC1103 assures so important, however adding unnecessary impedance will reduce efficiency. that the high-side MOSFET driver outputs remain in the off state whenever the supply voltage drops below set parameters. Lockout occurs if V falls below 3.8V. Nor- CC mal operation resumes once V rises above 3.8V. CC www.semtech.com  2005 Semtech Corp. 4 SC1103 POWER MANAGEMENT Applications Information (Cont.) Layout diagram for the SC1103 V = V (1 + Ra/Rb) O REF 20-24V BST 12VIN 10 0.1uF Cin + Q1 SC1103CS 1 8 VCC GND Vout 7 2 CS(-) FB Rb 6uH + 3 6 D1 CS(+) BST Cout 4 5 0.001uF PGND DH Ra Heavy lines indicate high current paths. Application Circuit 12V to 2.5V @ 10A (Bootstrapped) D1 C7 LL4148 0.1 L1 R5 Q1 6uH 0.05 IRLR3103 + +12V R6 76.8 *see note C11 C8 C9 C10 1.0 C1 220/4V 220/4V 220/4V C2 C3 D2 Vout = 2.5V @ 10A 1.0 MBRD1035L R7 47/16V 47/16V 127 GND GND R1 10 R2 R3 U1 1k 1k SC1103 C6 R4 0.01 2.2 1 8 VCC GND 2 7 CS(-) FB C4 C5 0.001 0.1 3 6 CS(+) BST 4 5 PGND DH * NOTE: R6 = R7 x (Vout/1.25 - 1) rounded to nearest 1%value  2005 Semtech Corp. 5 www.semtech.com SC1103 POWER MANAGEMENT Typical Characteristics Error Amplifier, Gain and Phase Load Regulation @ V = 12V IN 40 180 1.0% 35 0.8% 30 135 0.6% 25 0.4% Vo= 1.8V 0.2% 20 90 2.5V 0.0% 15 3.3V Gain -0.2% 5.0V 10 45 Phase -0.4% 5 -0.6% 0 0 -0.8% -5 -1.0% -10 -45 0 2 4 6 8 10 12 14 100.0E+0 1.0E+3 10.0E+3 100.0E+3 1.0E+6 10.0E+6 Output Current, (A) Frequency (Hz) V @ V = 12V, V = 3.3V, I = 10A Line Regulation @ V = 3.3V, I = 10A RIPPLE IN O O O O 0.5% 0.4% 0.3% 0.2% 0.1% 0.0% -0.1% -0.2% -0.3% -0.4% -0.5% 11.4 11.6 11.8 12.0 12.2 12.4 12.6 Input Voltage, (V) Efficiency @ V = 12V IN 100% 90% 80% 1.8V 2.5V 70% 3.3V 5V 60% 50% 40% 02 46 8 10 12 14 Output Current, (A) www.semtech.com  2005 Semtech Corp. 6 Efficiency Gain (dB) Phase (deg) Line Regulation Load Regulation SC1103 POWER MANAGEMENT Outline Drawing - SO-8 DIMENSIONS MILLIMETERS INCHES A DIM MIN NOM MAX MIN NOM MAX D e A .053 - .069 1.35 - 1.75 N - - A1 .004 .010 0.10 0.25 - - A2 .049 .065 1.25 1.65 - - 2X E/2 b .012 .020 0.31 0.51 c - - .007 .010 0.17 0.25 E1 D .189 .193 .197 4.80 4.90 5.00 E E1 .150 .154 .157 3.80 3.90 4.00 E .236 BSC 6.00 BSC e .050 BSC 1.27 BSC 12 h .010 - .020 0.25 - 0.50 ccc C L .016 .028 .041 0.40 0.72 1.04 2X N/2 TIPS e/2 L1 (.041) (1.04) N 8 8 B - - 01 0° 8° 0° 8° aaa .004 0.10 bbb .010 0.25 D ccc .008 0.20 aaa C A2 h A SEATING PLANE h C A1 H bxN bbb C A-B D c GAGE PLANE 0.25 L 01 (L1) SEE DETAIL A DETAIL A SIDE VIEW NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS AND TO BE DETERMINED AT DATUM PLANE -A- -B- -H- 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. REFERENCE JEDEC STD MS-012, VARIATION AA. 4. Minimum Land Pattern - SO-8 X DIMENSIONS DIM INCHES MILLIMETERS C (.205) (5.20) G .118 3.00 (C) G Z P .050 1.27 X .024 0.60 Y .087 2.20 Y Z .291 7.40 P NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. REFERENCE IPC-SM-782A, RLP NO. 300A. Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804  2005 Semtech Corp. 7 www.semtech.com