MAX848/MAX849 19-1095 Rev 2 12/97 1-Cell to 3-Cell, High-Power, Low-Noise, Step-Up DC-DC Converters General Description Features The MAX848/MAX849 boost converters set a new stan- Up to 95% Efficiency dard of high efficiency and high integration for noise- (see Typical Output Selector Guide below) sensitive power-supply applications, such as portable 3.3V Dual Mode or 2.7V to 5.5V Adj. Output phones and small systems with RF data links. The heart of the these devices is a synchronous boost-topology 0.7V to 5.5V Input Range regulator that generates a fixed 3.3V output (or 2.7V to 0.15mW Standby Mode 5.5V adjustable output) from one to three NiCd/NiMH cells or one Li-Ion cell. 300kHz PWM Mode or Synchronizable Synchronous rectification provides a 5% efficiency Two-Channel ADC with Serial Output improvement over similar nonsynchronous boost regu- lators. In standby mode, pulse-skipping PFM operation Power-Good Function keeps the output voltage alive with only 150W quies- cent power consumption. Fixed-frequency PWM opera- Applications tion ensures that the switching noise spectrum is limited to the 300kHz fundamental and its harmonics, allowing Digital Cordless Phones PCS Phones easy post-filtering noise reduction. For even tighter noise spectrum control, synchronize to a 200kHz to Cellular Phones Hand-Held Instruments 400kHz external clock. Palmtop Computers Personal Communicators Battery monitoring is provided by a two-channel, volt- age-to-frequency analog-to-digital converter (ADC). Local 3.3V to 5V Supplies One channel is intended for a single-cell battery input (0.625V to 1.875V range), while the other channel is for monitoring higher voltages (0V to 2.5V range). Ordering Information Two control inputs are provided for push-on, push-off PART TEMP. RANGE PIN-PACKAGE control via a momentary pushbutton switch. Upon MAX848ESE -40C to +85C 16 Narrow SO power-up, an internal comparator monitors the output MAX849ESE -40C to +85C 16 Narrow SO voltage to generate a power-good output (POK). The devices differ only in the current limit of the N-channel MOSFET power switch: 0.8A for the MAX848, and 1.4A for the MAX849. Typical Operating Circuit INPUT 0.8V TO 5.5V Typical Output Selector Guide V V MAX849 I MAX848 I IN OUT OUT OUT MAX848 (V) (V) (mA) (mA) MAX849 A/D CHANNEL 1 IN AIN1 LX OUTPUT 3.3 100 70 0.9 A/D CHANNEL 2 IN AIN2 5 70 40 A/D CHANNEL SELECT AINSEL OUT 3.3 300 110 A/D OUTPUT DATA POUT 1.2 5 200 70 ON1 ON/OFF CONTROL 3.3 750 200 ON2 POK VOLTAGE MONITOR 2.4 OUTPUT 5 500 130 SYNC INPUT CLK/SEL POKIN FB 3.3 800 250 2.7 5 600 150 REF GND PGND 3.6 5 1000 300 Pin Configuration appears at end of data sheet. Dual Mode is a trademark of Maxim Integrated Products. Maxim Integrated Products 1 For free samples & the latest literature: 1-Cell to 3-Cell, High-Power, Low-Noise, Step-Up DC-DC Converters ABSOLUTE MAXIMUM RATINGS ON1, ON2, OUT, POUT to GND..................................-0.3V, +6V Operating Temperature Range MAX848ESE/MAX849ESE .................................-40C to +85C PGND to GND ..........................................................-0.3V, +0.3V LX to PGND ...............................................-0.3V, (V + 0.3V) Junction Temperature......................................................+150C POUT Storage Temperature.........................................-65C to +160C CLK/SEL, DATA, POKIN, REF, AINSEL, AIN1, AIN2, FB, POK to GND .....-0.3V, (V + 0.3V) Lead Temperature (soldering, 10sec) .............................+300C OUT Continuous Power Dissipation (T = +70C) A Narrow SO (derate 8.7mW/C above +70C) ................696mW 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, GND = PGND = CLK/SEL = ON1 = ON2 = AINSEL = AIN1 = AIN2 = FB = POKIN, POUT = OUT, T = 0C to +85C, OUT A unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage (Note 1) 0.7 V REFERENCE Reference Output Voltage I = 0mA 1.23 1.25 1.27 V REF REF Load Regulation -1A < I < 50A 5 15 mV REF REF Supply Rejection 2.5V < V < 5V 0.2 5 mV OUT DC-DC CONVERTER Output Voltage (Note 2) V < 0.1V, CLK/SEL = OUT 3.17 3.34 3.40 V FB MAX848 110 V = 3.3V OUT MAX849 300 V = 1.2V IN MAX848 70 V = 5V OUT MAX849 200 mA MAX848 200 V = 3.3V OUT MAX849 750 V = 2.4V IN MAX848 130 Output Current V = 5V mA OUT MAX849 500 MAX848 250 V = 3.3V OUT MAX849 600 V = 2.7V IN MAX848 150 V = 5V OUT MAX849 800 MAX848, V = 3.3V 300 IN V = 5V OUT MAX849, V = 3.6V 1000 IN FB Regulation Voltage Adjustable output, CLK/SEL = OUT 1.215 1.240 1.265 V FB Input Current V = 1.25V 200 nA FB Output Voltage Adjust Range 2.7 5.5 V Output Voltage Lockout Range (Note 3) 2.1 2.4 V Load Regulation (Note 4) CLK/SEL = OUT -1.6 % Minimum Start-Up Voltage (Note 5) I < 1mA, T > +25C 0.9 1.1 V LOAD A Frequency in Start-Up Mode V = 1.5V 40 300 kHz OUT Operating Current in Shutdown Current into OUT pin, V = 3.6V 4 20 A ON2 2 MAX848/MAX849