SC194B Selectable 3.6V/3.3V/3.0V/2.5V 1A Synchronous Buck Converter POWER MANAGEMENT Description Features The SC194B is a synchronous step-down converter with Up to 95% ef ciency integrated power devices. Four selectable output voltages PSAVE operation to maximize ef ciency suitable for portable device interface, memory function Output current 1A blocks, and 5V to 3.3V voltage conversion are available. Input range 2.7V to 5.5V Four selectable output voltages Automatic selection of Power Save Mode (PSAVE) is Quiescent current 17A in PSAVE supported which enhances ef ciency. A 100% duty cycle Dynamic voltage positioning capability mode allows operation for input voltages close to the Fixed 1MHz frequency or 750kHz to 1.25MHz syn- required output voltage. chronized operation Current mode operation for excellent line and load The need for external components is minimized by transient response providing internal feedback compensation, and allowing 100% duty cycle in dropout selection of the required output voltage by hard wiring VID Soft-start code inputs. The maximum current rating of the internal Over-temperature and short-circuit protection MOSFET switches allows a DC output current of 1A. Lead-free package 3mm x 3mm MLPD The switching frequency is nominally set to 1MHz, allowing Applications the use of small inductors and capacitors. A exible PDA clocking scheme is used that allows synchronization to an Pocket PC and Smart Phones external oscillator or control by the internal oscillator. USB Powered Modems CPUs and DSPs The device can operate in either forced PWM mode or PC Cards and Notebooks in PSAVE mode. If PSAVE mode is enabled the part will xDSL Applications automatically enter PSAVE at light loads to maintain Standard 5-V to 3.3-V Conversion maximum ef ciency across the full load range. For noise sensitive applications, PSAVE mode can be disabled by synchronizing to an external oscillator, or pulling the SYNC/ PWM pin high. Shutdown turns off all the control circuitry to achieve a typical shutdown current of 0.1A. Typical Application Circuit L1 SC194B V OUT VIN LX 3.3V V IN EN 4.7 H 1A 3.6V to 5.5V SYNC/PWM VOUT C C IN OUT VID0 VID1 PGND 10 F 22 F MODE GND 1 August 24, 2006 www.semtech.comSC194B POWER MANAGEMENT Absolute Maximum Ratings Exceeding the speci cations below may result in permanent damage to the device or device malfunction. Operation outside of the parameters speci ed in the Electrical Characteristics section is not recommended. Parameter Symbol Maximum Units Input Supply Voltage V -0.3 to 7 V IN Logic Inputs V -0.3 to V +0.3, 7V Max V N IN (SYNC/PWM, EN, MODE, VID0, VID1) Output Voltage V -0.3 to V +0.3, 7V Max V OUT IN LX Voltage V -1 to V +1, 7V Max V LX IN (1) Thermal Impedance Junction to Ambient 40 C/W JA VOUT Short-Circuit to GND t Continuous s SC Operating Ambient Temperature Range T -40 to +85 C A Storage Temperature T -60 to +160 C S Junction Temperature T -40 to +150 C JC Peak IR Re ow Temperature T 260 C P (2) ESD Protection Level V 2kV ESD Note: (1) Calculated from package in still air, mounted to 3 x 4.5, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. (2) Tested according to JEDEC standard JESD22-A114-B. Electrical Characteristics Unless otherwise noted: V = 5V ,V = 3.3V, EN = V , SYNC/PWM = V , MODE = V , T = -40 to 85C. Typical values are at T =25C. IN OUT IN IN IN A A Parameter Symbol Conditions Min Typ Max Units Input Voltage Range V V > V + dropout 2.7 5.5 V IN IN OUT I = 0.5A, T = 25C OUT A VOUT Accuracy V 1% OUT V = 2.5/3.0/3.3/3.6V OUT VOUT Temperature Accuracy V I = 0.5A, T =-40C to 85C 0.3 0.7 % OUT(T) OUT A V = 2.7V to 5.5V, V = 2.5V, IN OUT Line Regulation V 0.4 0.65 % OUT LINE I = 0.5A, T =-40C to 85C OUT A Load Regulation (PWM) V I = 0A to 1A 0.3 0.65 % OUT LOAD OUT +1.3 +1.6 PSAVE Regulation V SYNC/PWM = GND, C =22 F % OUT PSAVE OUT -0.3 -0.6 P-Channel On Resistance R I = 100mA, V =3.6V 0.275 DSP LX IN N-Channel On Resistance R I = 100mA, V =3.6V 0.165 DSN LX IN Start-Up Time T 5ms START P-Channel Current Limit I V = 2.7V to 5.5V 1.33 1.9 2.47 A LIM(P) IN 2 2006 Semtech Corp. www.semtech.com