SC1101 Asynchronous Voltage Mode PWM Controller POWER MANAGEMENT Description Features The SC1101 is a versatile, low-cost, voltage-mode PWM Low cost / small size controller designed for low output voltage DC/DC power Switch mode efficiency up to 95% supply applications. A simple, fixed-voltage buck 1% reference voltage accuracy regulator can be implemented using the SC1101 with a Over current protection minimum of external components. Internal level shift and 500mA output drive drive circuitry eliminates the need for an expensive SO-8 package p-channel, high-side switch. The small device footprint allows for compact circuit design. SC1101 features include a temperature compensated Applications voltage reference, triangle wave oscillator, current limit Pentium P55 Core Supply comparator, frequency shift over-current protection, and Low Cost Microprocessor Supplies an internally compensated error amplifier. Pulse by pulse Peripheral Card Supplies current limiting is implemented by sensing the differential voltage across an external resistor, or an Industrial Power Supplies appropriately sized PC board trace. High Density DC/DC Conversion The SC1101 operates at a fixed frequency of 200kHz, providing an optimum compromise between efficiency, external component size, and cost. Typical Application Circuit L1 R5 Vout = 2V 10A Q1 4uH 0.05 IRLR3103 + +5V R6 76.8 *see note C8 C9 C10 C11 1.0 C1 330/2.5V 330/2.5V 330/2.5V C2 C3 D2 1.0 MBRD1035L R7 150/6.3V 150/6.3V 127 GND GND +12V R1 10 R2 R3 U1 1k 1k SC1101 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 1 Revision: May 25, 2005 www.semtech.comSC1101 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. Plarameter Smymbo Msaximu Unit IVnput Voltage t7o GND -V0.3 to + CC GPround Differential t1o GND V GND BDoost Input Voltage B5ST to GN -V0.3 to +1 OTperating Ambient Temperature Range 0Cto +70 AMB STtorage Temperature Range -C45 to 125 STG MTaximum Junction Temperature 1C25 J LTead Temperature (Soldering) 10 Sec. 3C00 LEAD Thermal Resistance Junction to Ambient 1W65 C/ JA Thermal Resistance Junction to Case 4W0 C/ JC Electrical Characteristics Unless specified: V = 4.75 to 5.25, GND = P = 0V, V = 2.5V, T = 25C, BST = 12V. CC GND O A Per test circuit, unless otherwise specified. Plarameter SsymboCnondition Mpi Txy Msa Unit RVeference 10.23813.25 1V.26 REF O5ver 0 to 125C Temp. range10.2215.25 1.27 FIeedback Bias Current 20.0 8A. u FB QIuiescent Current Current into Vp0in 50. 8A. m Q CC LIoad Regulation =51A to 10A 00. 1%. O LIine Regulation =510A 0%. O C)urrent Limit Threshold C0S(+) to CS(- 60708Vm Oscillator Frequency 1070 200 2z3 kH OVscillator Frequency Shift < V/02 5zkH FB REF Max Duty Cycle 9509% DIH Sink/Source Current V - V = 4.5V / V -V=02V5A0 m O BST DH DH PGND UVVLO 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