MAX847 19-1349 Rev 1a 10/98 1-Cell, Step-Up Two-Way Pager System IC General Description Features The MAX847 is a complete power-supply and monitor- 80mA Output from 1 Cell at 90% Efficiency ing system for two-way pagers or other low-power digi- 13A Idle Mode (coast) Current tal communications devices. It requires few external components. Included on-chip are: Selectable Low-Noise PWM or Low-Current A 1-cell input, 80mA output, synchronous-rectified Operation boost DC-DC regulator with a digitally controlled PWM Operating Frequency Synchronized to +1.8V to +4.9V output Seven Times an External Clock Source Three low-noise linear-regulator outputs Operates at 270kHz with No External Clock Three DAC-controlled comparators for software- driven 3-channel A/D conversion Automatic Backup-Battery Switchover SPI-compatible serial interface Ordering Information Reset and low-battery (LBO) warning outputs PART TEMP. RANGE PIN-PACKAGE Charger for NiCd, NiMH, lithium battery, or storage MAX847EEI -40C to +85C 28 QSOP capacitor for RF PA power or system backup Two 1.8W (typical) serial-controlled open-drain Applications MOSFET switches Two-Way Pagers An evaluation kit for the MAX847 (MAX847EVKIT) is GPS Receivers available to aid in design and prototyping. 1-Cell Powered Hand-Held Equipment Pin Configuration appears at end of data sheet. Typical Operating Circuit INPUT SINGLE AA ALKALINE BATTERY 0.8V TO 1.8V BATT LOW-BATTERY LBI LX1 IN/OUT LBO OUT RSIN RESET PGND RSO IN/OUT CS REG2IN SERIAL SCL I/O MAX847 SDI SDO OFS DR1 1.8 DR2 OUTPUT 2 DRIVERS REG2 2.85V ANALOG DR2IN DRGND OUTPUT 1 REG1 3V LOGIC RUN RUN COAST OUTPUT 3 REG3 1V RECEIVER A/D INPUT CH0 SYNC NICD TO RF PA FILT REF AGND OPTIONAL NiCd BATTERY STACK OR STORAGE CAPACITOR 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: 1-Cell, Step-Up Two-Way Pager System IC ABSOLUTE MAXIMUM RATINGS BATT, OUT, NICD, LBO, RSO to AGND...................-0.3V to +6V LX1 to PGND .............................................-0.3V to (OUT + 0.3V) REG1, OFS, REG2, REF, R2IN to AGND...-0.3V to (OUT + 0.3V) Continuous Power Dissipation (T = +70C) A SCL, SDO, SDI, CS , SYNC, FILT, DR2IN, 28-Pin QSOP (derate 8mW/C above +70C) .............640mW CH0, LBI, RSIN, RUN 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 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 = 1.2V, NICD = 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 OUT x Run or Coast Mode V 0.8 (Note 2) 0.8 BATT Minimum Start-Up Voltage T = +25C 0.9 1.1 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 0.5 2 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, 1.2 3 A (Note 8) BATT = 0V and 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 W DR1, DR2 On-Resistance I = 120mA 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 Includes CS, SDI, SCL, DR2IN, SYNC, and RUN 0.4 V V REG1 Logic Input Level High Includes CS, SDI, SCL, DR2IN, SYNC, and RUN V - 0.4 Logic Input = 0 to 3.3V includes CS, SDI, SCL, Logic Input Current -1 1 A DR2IN, SYNC, and RUN SERIAL-INTERFACE TIMING SPECIFICATIONS (Note 9) SCL Maximum Clock Rate 50% duty cycle 5 MHz SDI Setup Time, t 100 ns DS SDI Hold Time, t 50 ns DH 2 MAX847