+ LT1306 Synchronous, Fixed Frequency Step-Up DC/DC Converter FEATURES DESCRIPTIO n Output Disconnected from Input During Shutdown The LT 1306 is a fully integrated, fixed frequency syn- n Output Voltage Remains Regulated chronous boost converter capable of generating 5V at 1A When V > V from a Li-Ion cell. The device contains both the main IN OUT n Controlled Input Current During Start-Up power switch and synchronous rectifier on chip and n 300kHz Current Mode PWM Operation automatically disconnects the output from the input in n Can Be Externally Synchronized shutdown, eliminating the need for external load discon- n Internal 2A Switches nect circuitry. Additionally, the output remains regulated n Operates with V as Low as 1.8V when V exceeds V , allowing difficult step-up/step- IN IN OUT n Automatic Burst Mode Operation at Light Loads down converter functions to be easily realized using a n Quiescent Current: 160m A single inductor. n Shutdown Current: 9m A Typ The internal 300kHz oscillator of the LT1306 can be easily synchronized to an external clock from 425kHz to 500kHz. U This allows switching harmonics to be tightly controlled APPLICATIO S and eliminates any beat frequencies that may result from n Satellite Phones a multifrequency system. The LT1306 automatically shifts TM n Portable Instruments into power saving Burst Mode operation at light loads. n Personal Digital Assistants At heavy loads the LT1306 operates in fixed frequency n Palmtop Computers current mode. No-load quiescent current is 160m A and reduces to 9m A in shutdown mode. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. The LT1306 is available in an SO-8 package. TYPICAL APPLICATION D1 Efficiency 90 C1 L1 1m F 10m H 1-CELL 85 V = 4.2V IN Li-Ion V SW CAP 80 IN V = 3.6V IN 5V S/S OUT 1A R1 V = 2.6V 75 IN LT1306 + 768k C C IN1 IN2 FB 22m F 0.1m F 70 + V GND C C C O1 O2 220m F 1F V = 5V O 65 R3 R2 C : AVX TAJC226M010 IN1 C L1 = 10H P 118k 249k C : AVX TPSE227M010R0100 O1 (FIGURE 1) 68pF C , C : CERAMIC C IN1 O2 60 Z C1: AVX TAJA105K020 1 10 100 1000 68nF D1: MMBD914LT1 LOAD CURRENT (mA) 1306 F01 L1: CTX10-2 1306 TA01 Figure 1. Single Li-Ion Cell to 5V Converter 1 EFFICIENCY (%) U ULT1306 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) V Voltage ............................................................. 10V IN ORDER PART S/S Voltage ............................................................... 7V NUMBER TOP VIEW FB Voltage .............................................................. 10V 1 8 V S/S C LT1306ES8 V Voltage.......................................................... 5.5V OUT FB 2 7 V IN Junction Temperature.......................................... 125 C V 3 6 CAP OUT Operating Temperature Range (Note 2) .. 40 C to 85 C GND 4 5 SW Storage Temperature Range ................. 65 C to 150 C S8 PART MARKING S8 PACKAGE Lead Temperature (Soldering, 10 sec).................. 300 C 8-LEAD PLASTIC SO 1306 T = 125 C, q = 90 C/ W JMAX JA Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 2.5V, V = V , V open unless otherwise noted. A IN S/S IN C PARAMETER CONDITIONS MIN TYP MAX UNITS Reference Voltage Measured at the FB Pin l 1.22 1.24 1.26 V Reference Line Regulation 1.8V V 7V 0.002 0.1 %/V IN FB Input Bias Current V = V l 10 25 nA FB REF 1 Error Amplifier Transconductance D I = 0.2m A 80 150 220 Error Amplifier Output Source Current V = 1V, V = 0.8V 5 7.5 11 m A FB C Error Amplifier Output Sink Current V = 1.5V, V = 0.8V 5 7.5 11 m A FB C Error Amplifier Output Clamp Voltage V = 1V 1.18 1.28 1.38 V FB V Undervoltage Lockout Threshold 1.55 1.8 V IN Idle Mode Output Leakage Current V = 1.5V, V = 5.5V, V = 1.7V l 615 m A FB OUT SW Output Source Current in Shutdown V = 0V, V = V = 7V, V = 7.2V, V = 0V l 3 m A OUT IN SW CAP S/S Switching Frequency 1.8V V 7V, 0 C T 85 C l 260 310 415 kHz IN A 1.8V V 7V, T = 40 C 225 305 390 kHz IN A Maximum Duty Cycle V = 1V, 0 C T 85 C8090 % FB A V = 1V, T = 40 C6580 % FB A Switch Current Limit Duty Cycle = 0.1 (Note 3) 2.3 A Duty Cycle = 0.8 (Note 3) 2.0 A Burst Mode Operation Switch Current Limit 250 mA Switch V I = 2A 0.45 0.575 V CESAT SW Rectifier V I = 2A 0.49 0.675 V CESAT SW Stepdown Mode Rectifier Voltage V = 0V, I = 1A 0.3 + V 0.7 + V V OUT SW IN IN V = 2.2V, I = 1A 1.3 1.8 V OUT SW Switch and Rectifier Leakage Current V = 0V, V = V = 7V, V = 7.2V, V = 0V l 0.1 20 m A OUT IN SW CAP S/S 2 mW U W U W U WW