MAX769

Features:

* Regulated Step-Up/Step-Down Operation
* 80mA Output from 3 Cells
* 85% Efficiency
* 13µA Idle Mode™ (coast) Current
* Selectable Low-Noise PWM or Low-Current PFM
   Operation
* PWM Operating Frequency Synchronized to
   Seven Times an External Clock Source
* Operates at 270kHz with No External Clock
* Automatic Backup-Battery Switchover


Application

* Two-Way Pagers
* GPS Receivers
* 2 or 3-Cell Powered, Hand-Held Equipment


Pinout




Specifications

BATT, OUT, NICD, LBO, RSO to AGND......................-0.3V to +6V
REG1, REG2, OFS, REF, R2IN to AGND .....-0.3V to (OUT + 0.3V)
SCL, SDO, SDI, CS, SYNC, FILT, DR2IN,
   CH0, LBI, RSIN to AGND......................-0.3V to (REG1 + 0.3V)
REG3 .....................................................-0.3V to (REG2 + 0.3V)
DR1, DR2 to DRGND ...............................-0.3V to (BATT + 0.3V)
PGND, DRGND to AGND.......................................-0.3V to +0.3V
LX1 to PGND ...........................................-0.3V to (OUT + 0.3V)
LX2 to PGND...........................................-0.3V to (BATT + 0.3V)
Continuous Power Dissipation (T_A = +70)
   QSOP (derate 8mW/ above +70)........................640mW
Operating Temperature Range .........................-40 to +85
Junction Temperature....................................................+150
Storage Temperature Range ...........................-65 to +165
Lead Temperature (soldering, 10sec) ...........................+300


Description

The MAX769 is a complete buck/boost power supply and monitoring system for two-way pagers or other lowpower digital communications devices. Few external components are required. Included on-chip MAX769 are:

· An 80mA output, synchronous-rectified, buck/boost
    DC-DC converter with a digitally controlled +1.8V to
    +4.9V output. The DC-DC converter is unique, since
    it provides a regulated output for battery inputs that
    are both less than and greater than the output voltage,
    without using transformers.
· Three low-noise linear-regulator outputs
· Three DAC-controlled comparators for softwaredriven,
    3-channel A/D conversion
· SPI™-compatible serial interface
· Reset and low-battery (LBO) warning outputs
· Charger for NiCd/NiMH, lithium battery, or storage
    capacitor for RF PA power or system backup
· Two 1.8½ (typical), serial-controlled, open-drain

MOSFET switches for beeper or vibrator drive An evaluation kit for the MAX769 (MAX769EVKIT) is available to aid in design and prototyping.