MAX1692 19-1400 Rev 0 11/98 Low-Noise, 5.5V-Input, PWM Step-Down Regulator General Description Features The MAX1692 is a low-noise, pulse-width-modulated +2.7V to +5.5V Input Range (PWM), DC-DC step-down converter. It powers logic Adjustable Output from 1.25V to V IN and transmitters in small wireless systems such as cellu- lar phones, communicating PDAs, and handy-terminals. 600mA Guaranteed Output Current The device features an internal synchronous rectifier for 95% Efficiency high efficiency it requires no external Schottky diode. No Schottky Diode Required Excellent noise characteristics and fixed-frequency operation provide easy post-filtering. The MAX1692 is 85A Quiescent Current ideally suited for Li-Ion battery applications. It is also 100% Duty Cycle in Dropout useful for +3V or +5V fixed input applications. The device operates in one of four modes. Forced PWM 750kHz Fixed-Frequency PWM Operation mode operates at a fixed frequency regardless of the Synchronizable Switching Frequency load. Synchronizable PWM mode allows an external Accurate Reference: 1.25V (1.2%) switching frequency to control and minimize harmonics. Idle Mode (PWM/PFM) extends battery life by switch- Small 10-Pin MAX Package ing to a PFM pulse-skipping mode during light loads. Shutdown mode places the device in standby, reduc- Ordering Information ing quiescent supply current to under 0.1A. PART TEMP. RANGE PIN-PACKAGE The MAX1692 can deliver over 600mA. The output volt- MAX1692EUB -40C to +85C 10 MAX age can be adjusted from 1.25V to V with the input IN range of +2.7V to +5.5V. Other features of the MAX1692 include high efficiency, low dropout voltage, Pin Configuration and a 1.2%-accurate 1.25V reference. It is available in a space-saving 10-pin MAX package with a height of TOP VIEW only 1.11mm. IN 1 10 PGND Applications BP 2 9 LX Cellular Phones CPU I/O Supplies MAX1692 GND 3 8 SHDN Cordless Phones Notebook Chipset Supplies REF 4 7 SYNC/PWM PDAs and Handy-Terminals Battery-Operated Devices FB 5 6 LIM (1 Li-Ion or 3 NiMH/NiCd) MAX Typical Operating Circuit L IN V = 2.7V TO 5.5V LX V = 1.25V TO V IN OUT IN SHDN C1 C2 R1 LIM FB MAX1692 R2 BP SYNC/PWM PGND C3 AGND REF C4 Idle Mode is a trademark of Maxim Integrated Products. Maxim Integrated Products 1 For free samples & the latest literature: Low-Noise, 5.5V-Input, PWM Step-Down Regulator ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (T = +70C) IN, BP, SHDN, SYNC/PWM, LIM to GND ................ -0.3V to +6V A BP to IN .................................................................-0.3V to +0.3V 10-Pin MAX (derate 5.6mW/C above +70C) ............444mW Operating Temperature Range .......................... -40C to +85C PGND to GND ...................................................... -0.3V to +0.3V LX to PGND................................................. -0.3V to (V + 0.3V) Maximum Junction Temperature .................................... +150C IN Storage Temperature Range ............................ -65C to +160C FB, REF to GND ......................................... -0.3V to (V + 0.3V) BP Reference Current ............................................................. 1mA Lead Temperature (soldering, 10sec) .............................+300C LX Peak Current (internally limited)...................................... 1.6A Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = +3.6V, SYNC/PWM = GND, V = 3.6V, SHDN = IN, circuit of Figure 2 T = 0C to +85C, unless otherwise noted. Typical IN LIM A values are at T = +25C.) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage Range V 2.7 5.5 V IN FB = OUT, V = V = 2.7V to 5.5V, IN LIM 1.223 1.249 1.275 I = 0 OUT Output Voltage V V OUT FB = OUT, V = 2.7V to 5.5V, IN I = 0 to 600mA, LIM = IN or 1.190 1.232 1.275 OUT I = 0 to 250mA, LIM = GND OUT Output Adjustment Range (Note 1) V V V REF IN FB = OUT, V = V = 5.5V, I = 0 IN LIM OUT Feedback Voltage V 1.223 1.249 1.275 V FB (duty cycle = 23%) (Note 2) Line Regulation Duty cycle = 100% to 23% +1 % I = 0 to 600mA, LIM = IN or OUT Load Regulation -1.3 % I = 0 to 250mA, LIM = GND OUT FB Input Current I V = 1.4V -50 0.01 50 nA FB FB V = 3.6V 0.3 0.65 IN W P-Channel On-Resistance P I = 180mA RDS(ON) LX V = 2.7V 0.4 IN V = 3.6V 0.4 0.8 IN W N-Channel On-Resistance N I = 180mA RDS(ON) LX V = 2.7V 0.5 IN LIM = GND 0.35 0.6 0.85 P-Channel Current-Limit A Threshold LIM = IN 0.75 1.2 1.55 V = 1.4V -450 -850 -1600 N-Channel Current-Limit FB mA Threshold SYNC/PWM = IN, FB = REF 0 50 100 Pulse-Skipping Current-Limit 80 120 160 mA Threshold SYNC/PWM = GND, V = 1.4V, FB Quiescent Current 85 140 A LX unconnected SHDN = LX = GND, includes LX leakage Shutdown Supply Current 0.1 10 A current LX Leakage Current V = 5.5V, V = 0 or 5.5V -20 0.1 20 A IN LX Oscillator Frequency f 650 750 830 kHz OSC SYNC Capture Range 500 1000 kHz Maximum Duty Cycle duty 100 % MAX Minimum Duty Cycle duty 22 % MIN Reference Output Voltage V I = 0 1.235 1.250 1.265 V REF REF 2 MAX1692