POWER LOSS (W) LTC1700 No R Synchronous SENSE Step-Up DC/DC Controller FEATURES DESCRIPTIO High Efficiency: Up to 95% The LTC 1700 is a current mode synchronous step-up No Current Sense Resistor Required DC/DC controller that drives external N-channel and Constant Frequency 530kHz Operation Allows P-channel power MOSFETs using a constant frequency Small Size, Surface Mount Inductors PWM architecture. Current limiting is provided by sensing OPTI-LOOP Compensation Minimizes C the voltage drop across the main MOSFET, eliminating the OUT TM Selectable Burst Mode Operation need of a sense resistor. This No R technique helps SENSE Minimum Start-Up Voltage as Low as 0.9V the LTC1700 maintain high efficiency at heavy loads while Synchronizable Between 400kHz and 750kHz Burst Mode operation ensures high efficiency at light loads, Micropower Shutdown: 10A thus providing high efficiencies over a wide range of load Current Mode Operation for Excellent Line and Load currents. Transient Response The LTC1700 operates at a minimum input voltage as low as Soft-Start Reduces Supply Current Transients 0.9V. The device boasts a 1.5% output voltage accuracy and 1.5% Output Voltage Accuracy consumes only 200A of quiescent current. In shutdown, it Uses Low Value, Small Size, Surface Mount Inductors only draws 10A. Available in 10-Lead MSOP Package To prevent inductor current runaway, the duty cycle is limited U APPLICATIO S to 90%. Overvoltage protection is also provided which shuts both the external MOSFETs off when tripped. Cellular Telephones Wireless Modems High constant operating frequency of 530kHz allows the use RF Communications of small inductors and output capacitors. The LTC1700 can 2.5V to 3.3V, 2.5V to 5V Converters also be synchronized between 400kHz to 750kHz. Burst Battery-Powered Equipment Mode operation is inhibited when the device is externally Telecom/Network Systems clocked or when the SYNC/MODE pin is pulled low to reduce , LTC and LT are registered trademarks of Linear Technology Corporation. noise and RF interference. Burst Mode, OPTI-LOOP are registered trademarks of Linear Technology Corporation. No R is a trademark of Linear Technology Corporation. SENSE V TYPICAL APPLICATIO IN 3.3V to 4.2V + C2 C1 68F Efficiency, Power Loss vs Load Current 22F L1 6.3V 1.8H 1.0 100 M2 2 10 5V 4.2V EFFICIENCY I SW TH 2A 90 R3 4 8 C6 80 RUN/SS BG M1 2200 10F C5 70 3.3V EFFICIENCY 220pF C4 0.1 C3 LTC1700 + C7 0.1F 60 220pF 330F 9 1 SGND PGND 6V 50 6 3 40 3.3V POWER V TG FB 0.01 R2 30 4.2V POWER 5 7 100k SYNC/MODE V R1 OUT 20 316k 10 1700 F01a 0 0.001 C1: CERAMIC TAIYO YUDEN LMK432BJ226MM C6: CERAMIC TAIYO YUDEN JMK316BJ106ML M1: SILICONIX Si9804 0.001 0.01 0.1 1 2 C2: AVX TAJB686K006R C7: SANYO POSCAP 6TPB330M M2: SILICONIX Si9803 LOAD CURRENT L1: TOKO 919AS-IR8N (D104C TYPE) 1700 F01b Figure 1. High Efficiency Step-Up Converter 1700fa 1 EFFICIENCY (%) U U LTC1700 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART Output Supply Voltage (V ) .....................0.3V to 6V OUT NUMBER RUN/SS, V Voltages ..............................0.3V to 2.4V FB TOP VIEW SYNC/MODE, I Voltages ...........................0.3V to 6V TH SGND 1 10 SW SWITCH Voltage (SW) ..............................0.3V to 6.5V LTC1700EMS I 2 9 PGND TH V 3 8 BG FB TG, BG Peak Output Current (<10s)......................... 1A RUN/SS 4 7 V OUT SYNC/MODE 5 6 TG Operating Temperature Range (Note 2) ...40C to 85C MS PART MS PACKAGE Junction Temperature (Note 3)............................. 125C MARKING 10-LEAD PLASTIC MSOP Storage Temperature Range ................. 65C to 150C T = 125C, = 150C/W JMAX JA Lead Temperature (Soldering, 10 sec).................. 300C LTLC Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 3V unless otherwise specified. A OUT SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Start-Up Minimum Operating Voltage (Note 4) 0.9 1.8 V SOP V Minimum Operating Voltage (Note 5) V Ramping Up 2.34 2.6 V OP OUT Hysteresis 90 mV I Input DC Supply Current (Note 6) S Normal Mode V = 1.6V, V = 0V, V = 3V 536 620 A FB MODE RUN/SS Sleep Mode V = 1.6V, V = 3V, V = 3V 179 210 A FB MODE RUN/SS = 0V, V , V V = 1.8V 35 45 A Start-Up Mode V FB MODE RUN/SS, OUT Shutdown V = 0V, V = 3V, V = 0V 10 14 A FB MODE RUN/SS I Feedback Current V = 1.20V 1 50 nA VFB FB V Regulated Output Voltage (Note 7) 1.187 1.205 1.223 V FB V Reference Voltage Line Regulation V = 2.7V to 5V (Note 7) 0.0106 0.080 %/V OSENS IN V Output Voltage Load Regulation Measured in Servo Loop V = 0.3V to 0.9V 0.036 0.065 % LOADREG ITH V Output Overvoltage Lockout Reference to Nominal V 2.5 4.8 9 % OVL FB V Shutdown Threshold V Ramping Up 0.7 1.09 1.2 V RUN/SS RUN/SS I Soft-Start Current Source V = 0V 2 3.79 6 A RUN/SS RUN/SS f Oscillator Frequency V = 4.2V 460 530 680 kHz OSC OUT Start-Up Oscillator Frequency V = 1.8V, V = 1.8V, V = 1.1V 150 225 kHz OUT RUN/SS SW V SYNC/MODE Threshold V Ramping Down from 1.2V 1.03 1.13 1.25 V SYNC/MODE SYNC/MODE DC MAX Maximum Duty Cycle f = 550kHz 84 88 92 % OSC V Maximum Current Sense Voltage 55 78 100 mV SENSE(MAX) 63 mV I Current Limit At Start-Up V = 1.8V 40 60 mA LIMIT OUT g Transconductance of Error Amplifier V = V 10mV 0.65 0.9 1.30 m m FB REF 1700fa 2 U WWW