MAX769 19-4771 Rev 1 10/98 2 or 3-Cell, Step-Up/Down, Two-Way Pager System IC General Description Features The MAX769 is a complete buck/boost power supply Regulated Step-Up/Step-Down Operation and monitoring system for two-way pagers or other low- 80mA Output from 3 Cells power digital communications devices. Few external 85% Efficiency components are required. Included on-chip are: 13A Idle Mode (coast) Current An 80mA output, synchronous-rectified, buck/boost DC-DC converter with a digitally controlled +1.8V to Selectable Low-Noise PWM or Low-Current PFM +4.9V output. The DC-DC converter is unique, since Operation it provides a regulated output for battery inputs that PWM Operating Frequency Synchronized to are both less than and greater than the output volt- Seven Times an External Clock Source age, without using transformers. Operates at 270kHz with No External Clock Three low-noise linear-regulator outputs Automatic Backup-Battery Switchover Three DAC-controlled comparators for software- driven, 3-channel A/D conversion Ordering Information SPI-compatible serial interface Reset and low-battery (LBO) warning outputs PART TEMP. RANGE PIN-PACKAGE Charger for NiCd/NiMH, lithium battery, or storage MAX769EEI -40C to +85C 28 QSOP capacitor for RF PA power or system backup Two 1.8 (typical), serial-controlled, open-drain Applications MOSFET switches for beeper or vibrator drive Two-Way Pagers An evaluation kit for the MAX769 (MAX769EVKIT) is GPS Receivers available to aid in design and prototyping. 2 or 3-Cell Powered, Hand-Held Equipment Pin Configuration appears at end of data sheet. Typical Operating Circuit INPUT 2 OR 3 AA ALKALINE BATTERIES 1.5V TO 5.5V BATT LX1 LOW-BATTERY LBI LX2 IN/OUT OUT LBO RSIN REJECT PGND RSO IN/OUT CS REG2IN SCL SERIAL SD1 I/O MAX769 SD03 OFS DR1 1.8 OUTPUT 2 DR2 DRIVERS REG2 2.85V ANALOG DR2IN DRGND OUTPUT 1 REG1 3V LOGIC OUTPUT 3 A/D CH0 REG3 1V RECEIVER INPUT SYNC TO RF PA NICD OPTIONAL FILT REF AGND NiCd STORAGE BATTERY OR CAPACITOR STACK Idle Mode is a trademark of Maxim Integrated Products. SPI is a trademark of Motorola, Inc. Maxim Integrated Products 1 For free samples & the latest literature: 2 or 3-Cell, Step-Up/Down, Two-Way Pager System IC ABSOLUTE MAXIMUM RATINGS BATT, OUT, NICD, LBO, RSO to AGND...................-0.3V to +6V LX2 to PGND............................................-0.3V to (BATT + 0.3V) REG1, REG2, OFS, REF, R2IN to AGND .....-0.3V to (OUT + 0.3V) Continuous Power Dissipation (T = +70C) A SCL, SDO, SDI, CS, SYNC, FILT, DR2IN, QSOP (derate 8mW/C above +70C)..........................640mW CH0, LBI, RSIN to AGND......................-0.3V to (REG1 + 0.3V) Operating Temperature Range ...........................-40C to +85C REG3 .......................................................-0.3V to (REG2 + 0.3V) Junction Temperature......................................................+150C DR1, DR2 to DRGND ...............................-0.3V to (BATT + 0.3V) Storage Temperature Range .............................-65C to +165C PGND, DRGND to AGND......................................-0.3V to +0.3V Lead Temperature (soldering, 10sec) .............................+300C LX1 to PGND .............................................-0.3V to (OUT + 0.3V) 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 (OUT = 3.0V, BATT = 3.6V, T = -40C to +85C, unless otherwise noted. Typical values are at T = +25C.) (Note 1) A A PARAMETER CONDITIONS MIN TYP MAX UNITS GENERAL PERFORMANCE BATT Typical Operating Range Run or Coast Mode 1.5 5.5 V (Note 2) BATT Minimum Start-Up Voltage T = +25C 1.6 2.0 V A (Note 3) Coast Mode Supply Current (Note 4) REG2, REG3 and CH DAC off, V = 2.8V 13 25 A OUT Run Mode Supply Current (Note 4) REG2, REG3 and CH DAC on 875 1350 A BATT Supply Current (Note 5) Coast Mode 4 10 A NICD Input Current, Standby Charger and Backup Modes off, NICD = 3.6V 1.2 3 A (Note 6) NICD Input Supply Current, Backup Backup Mode, NICD = 3.6V, OUT = 3V 20 40 A (Note 7) NICD Input Current, Power Fail Charger and Backup Modes off, BATT = 0V, 1.2 3 A (Note 8) OUT = 0V REG2 Supply Current (Note 4) Incremental supply current when on 50 A REG3 Supply Current (Note 4) Incremental supply current when on 20 A CH DAC Supply Current (Note 4) Incremental supply current when on 30 A Reference Voltage I = 0 to 20A, OUT = 1.8V to 4.9V -1.5% 1.28 1.5% V REF T = +25C 1.8 2.8 A DR1, DR2 On-Resistance I = 120mA W DR T = -40C to +85C 3.6 A DR1, DR2 Leakage Current V = 5V 1 250 nA DR SDO Output Low I = 100A 200 mV SDO V REG1 SDO Output High I = -100A, from REG1 V SDO - 0.2 Logic Input Level Low 0.4 V Includes CS, SDI, SCL, DR2IN, and SYNC V REG1 Logic Input Level High Includes CS, SDI, SCL, DR2IN, and SYNC V - 0.4 Logic Input = 0 to 3.3V includes CS, SDI, SCL, Logic Input Current -1 1 A DR2IN, and SYNC 2 MAX769