LTC3250-1.5/LTC3250-1.2 High Efficiency, Low Noise, Inductorless Step-Down DC/DC Converter FEATURES DESCRIPTIO n 2.7V to 5.5V Input Voltage Range The LTC 3250-1.5/LTC3250-1.2 are charge pump step- n No Inductors down DC/DC converters that produce a 1.5V or 1.2V n Li-Ion (3.6V) to 1.5V with 81% Efficiency regulated output from a 2.7V to 5.5V input. The parts use n Low Noise Constant Frequency Operation switched capacitor fractional conversion to achieve typi- n Output Voltages: 1.5V 4%, 1.2V 4% cal efficiency two times higher than that of a linear regu- n Output Current: 250mA lator. No inductors are required. n Shutdown Disconnects Load from V IN A unique constant frequency architecture provides a low n Low Operating Current: I = 35A Q noise regulated output as well as lower input noise n Low Shutdown Current: I < 1A SD than conventional charge pump regulators.* High n Oscillator Frequency = 1.5MHz frequency operation (f = 1.5MHz) simplifies filtering OSC n Soft-Start Limits Inrush Current at Turn-On to further reduce conducted noise. The part also uses n Short-Circuit and Overtemperature Protected Burst Mode operation to improve efficiency at light loads. n Low Profile (1mm) SOT-23 Package Low operating current (35A with no load, <1A in U shutdown) and low external parts count (three small APPLICATIO S ceramic capacitors) make the LTC3250-1.5/LTC3250-1.2 ideally suited for space constrained battery powered appli- n Handheld Computers cations. The parts are short-circuit and overtemperature n Cellular Phones protected, and are available in a low profile (1mm) 6-pin n Digital Cameras TM ThinSOT package. n Handheld Medical Instruments n , LTC and LT are registered trademarks of Linear Technology Corporation Low Power DSP Supplies Burst Mode is a registered trademark of Linear Technology Corporation ThinSOT is a trademark of Linear Technology Corporation. *U.S. Patent 6, 411, 531 TYPICAL APPLICATIO Efficiency vs Input Voltage (I = 100mA) OUT 100 Li-Ion to 1.5V Output with Shutdown 90 1F 80 LTC3250-1.5 70 60 + V C C IN V = 1.5V 4% 50 OUT 3.2V TO 4.2V V V IN OUT 100mA 40 Li-Ion 1F LDO LTC3250-1.5 4.7F 30 20 SHDN OFF ON GND 10 3250 TA1a 0 3.0 3.5 4.0 4.5 5.0 5.5 V (V) IN 3250 TA01b 3250fa 1 EFFICIENCY (%) U ULTC3250-1.5/LTC3250-1.2 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART V to GND ................................................... 0.3V to 6V IN NUMBER SHDN to GND ............................... 0.3V to (V + 0.3V) IN TOP VIEW I (Note 2)....................................................... 350mA LTC3250ES6-1.5 OUT + V 1 6 C IN Operating Ambient Temperature Range (Note 3) LTC3250ES6-1.2 GND 2 5 V OUT ........................................................... 40C to 85C SHDN 3 4 C Storage Temperature Range ................ 65C to 150C S6 PACKAGE S6 PART MARKING Lead Temperature (Soldering, 10 sec).................. 300C 6-LEAD PLASTIC SOT-23 LTZE T = 150C, = 230C/W, JMAX JA LTAGJ = 102C/W JC Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 3.6V, C = 1F, C = 1F, C = 4.7F unless otherwise noted. A IN FLY IN OUT SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V LTC3250-1.5 Operating Voltage Range l 3.1 5.5 V IN LTC3250-1.2 Operating Voltage Range l 2.7 5.5 V V LTC3250-1.5 Output Voltage Range I 50mA 3.1V V 5.5V l 1.44 1.5 1.56 V OUT OUT IN I 100mA 3.2V V 5.5V l 1.44 1.5 1.56 V OUT IN 250mA 3.5V V 5V 1.44 1.5 1.56 V I OUT IN LTC3250-1.2 Output Voltage Range I 150mA 2.7V < V < 5.5V l 1.15 1.2 1.25 V OUT IN I 250mA 2.9V V 5V 1.15 1.2 1.25 V OUT IN I Operating Current I = 0mA l 35 60 A IN OUT Shutdown Current SHDN = 0V l 0.01 1 A V Burst Mode Operation Output Ripple 12 mV RB P-P V Continuous Mode Output Ripple 4 mV RC P-P f Switching Frequency l 1.2 1.5 1.8 MHz OSC V SHDN Input Hi Voltage l 1.2 0.8 V IH V SHDN Input Low Voltage l 0.8 0.4 V IL I SHDN Input Current SHDN = V l 1 1 A IH IN I SHDN Input Current SHDN = 0V l 1 1 A IL t Turn On Time R = 6 0.8 ms ON LOAD LTC3250-1.5 Load Regulation 0 I 250mA 0.15 mV/mA OUT LTC3250-1.2 Load Regulation 0 I 250mA 0.12 mV/mA OUT Line Regulation I = 250mA 0.2 %/V OUT R Open-Loop Output Impedance I = 250mA (Note 4) 1.0 OL OUT Note 1: Absolute Maximum Ratings are those values beyond which the life Note 4: Output not in regulation R = (V /2 - V )/I . OL IN OUT OUT of a device may be impaired. Note 5: This IC includes overtemperature protection that is intended to Note 2: Based on long term current density limitations. protect the device during momentary overload conditions. Junction temperature will exceed 125C when overtemperature protection is active. Note 3: The LTC3250-1.5E/LTC3250-1.2E are guaranteed to meet Continuous operation above the specified maximum operating junction specified performance from 0C to 70C. Specifications over the 40C temperature may impair device reliability. and 85C operating temperature range are assured by design characterization and correlation with statistical process controls. 3250fa 2 U WWW