Datasheet

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________________General Description

The MAX1703 is a high-efficiency, low-noise, step-up

DC-DC converter intended for use in battery-powered

wireless applications. It uses a synchronous-rectified

pulse-width-modulation (PWM) boost topology to gen-

erate a 2.5V to 5.5V output from battery inputs, such as

one to three NiCd/NiMH cells or one Li-Ion cell. The

device includes a 2A, 75mΩ, N-channel MOSFET

switch and a 140mΩ, P-channel synchronous rectifier.

With its internal synchronous rectifier, the MAX1703

delivers up to 5% better efficiency than similar nonsyn-

chronous converters. It also features a pulse-frequency-

modulation (PFM) low-power mode to improve efficiency

at light loads, and a 1µA shutdown mode.

The MAX1703 comes in a 16-pin narrow SO package

and includes an uncommitted comparator that generates

a power-good or low-battery-warning output. It also

contains a linear gain block that can be used to build a

linear regulator.

For lower-power outputs and a smaller package, refer

to the MAX1700/MAX1701. For dual outputs (step-up

plus linear regulator), refer to the MAX1705/MAX1706.

For an on-board analog-to-digital converter, refer to the

MAX848/MAX849.

The MAX1703 evaluation kit is available to speed designs.

____________________________Features

♦ Up to 95% Efficiency

♦ Up to 1.5A Output

♦ Fixed 5V or Adjustable Step-Up Output

(2.5V to 5.5V)

♦ 0.7V to 5.5V Input Range

♦ Low-Power Mode (300µW)

♦ Low-Noise, Constant-Frequency Mode (300kHz)

♦ Synchronizable Switching Frequency

(200kHz to 400kHz)

♦ 1µA Logic-Controlled Shutdown

♦ Power-Good Comparator

♦ Uncommitted Gain Block

________________________Applications

Digital Cordless Phones Personal Communicators

PCS Phones Palmtop Computers

Wireless Handsets Hand-Held Instruments

Two-Way Pagers

MAX1703

1-Cell to 3-Cell, High-Power (1.5A),

Low-Noise, Step-Up DC-DC Converter

________________________________________________________________

Maxim Integrated Products

19-1336; Rev 2; 11/98

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

Ordering Information

Typical Operating Circuit

PART TEMP. RANGE

PIN-PACKAGE

MAX1703ESE -40°C to +85°C 16 Narrow SO

PGNDGNDFB

POUT

OUT

LXP, LXN

OFF

INPUT

0.7V TO 5.5V

SYNC

PWM

PFM

OUTPUT

5V OR ADJ

UP TO 1.5A

CLK/

SEL

POKIN

POK

AIN

REF

POWER-GOOD

INPUT

POWER-GOOD

OUTPUT

GAIN-BLOCK INPUT

GAIN-BLOCK

OUTPUT

MAX1703

Pin Configuration

REF ON

POUT

LXP

POUT

PGND

LXN

PGND

CLK/SEL

TOP VIEW

MAX1703

Narrow SO

POKIN

AIN

OUT

GND

POK

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

Summary of content (16 pages)

PAGE 1
9-1336; Rev 2; 11/98 NUAL KIT MA ATION EET H S A EVALU T WS DA FOLLO 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter ____________________________Features The MAX1703 is a high-efficiency, low-noise, step-up DC-DC converter intended for use in battery-powered wireless applications. It uses a synchronous-rectified pulse-width-modulation (PWM) boost topology to generate a 2.5V to 5.5V output from battery inputs, such as one to three NiCd/NiMH cells or one Li-Ion cell.
PAGE 2
MAX1703 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter ABSOLUTE MAXIMUM RATINGS OUT, ON, AO, POK to GND .....................................-0.3V to +6V PGND to GND.....................................................................±0.3V LXP, LXN to PGND .................................-0.3V to (VPOUT + 0.3V) POUT, CLK/SEL, AIN, REF, FB, POKIN to GND.......................................-0.3V to (VOUT + 0.3V) Continuous Power Dissipation (TA = +70°C) Narrow SO (derate 8.
PAGE 3
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter (CLK/SEL = AIN = ON = POKIN = FB = PGND = GND, OUT = POUT, LXP = LXN, VOUT = 5.3V (Note 1), TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS 1.25 1.263 V 30 nA 10 16 mmho GAIN BLOCK AIN Reference Voltage IAO = 20µA 1.237 AIN Input Current VAIN = 1.5V -30 Transconductance 10µA < IAO < 100µA AO Output Low Voltage VAIN = 0.5V, IAO = 100µA 0.1 0.
PAGE 4
MAX1703 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter ELECTRICAL CHARACTERISTICS (continued) (CLK/SEL = AIN = ON = POKIN = FB = PGND = GND, OUT = POUT, LXP = LXN, VOUT = 5.3V (Note 1), TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 8) PARAMETER CONDITIONS MIN TYP MAX UNITS DC-DC SWITCHES Switch On-Resistance N-channel CLK/SEL = GND 0.25 CLK/SEL = OUT 0.13 P-channel Ω 0.
PAGE 5
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter 70 90 VIN = 1.2V 60 PFM PWM 50 VIN = 0.9V 70 60 LOW-POWER MODE 100 1000 10,000 0.1 1 TA = +25°C TA = -40°C 10 100 1000 10,000 0 1 2 3 4 LOAD CURRENT (mA) INPUT VOLTAGE (V) SHUTDOWN SUPPLY CURRENT vs. INPUT VOLTAGE START-UP VOLTAGE vs. LOAD CURRENT REFERENCE VOLTAGE vs. TEMPERATURE 1.0 TA = +25°C, TA = -40°C 1.4 1.2 1.0 0.6 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 0.
PAGE 6
_________________________________Typical Operating Characteristics (continued) (VIN = +3.6V, VOUT = 5V, TA = +25°C, unless otherwise noted.) PEAK INDUCTOR CURRENT LIMIT vs. OUTPUT VOLTAGE FREQUENCY vs. TEMPERATURE 330 MAX1703-16 3.5 MAX1703-15 340 PWM 3.0 310 CURRENT LIMIT(A) 320 FREQUENCY (kHz) MAX1703 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter VOUT = 5V 300 290 2.5 2.0 1.5 280 VOUT = 3.3V LOW POWER (PFM) 1.0 270 0.5 260 -40 -20 0 20 40 60 80 2.
PAGE 7
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter GSM LOAD-TRANSIENT RESPONSE DECT LOAD-TRANSIENT RESPONSE MAX1703-12 MAX1703-13 VOUT (100mV/div) VOUT (100mV/div) ILOAD (0.5A/div) ILOAD (0.2A/div) 1ms/div 2ms/div VIN = 3.6V, VOUT = 5V, COUT = 470µF, PULSE WIDTH = 577µs, LOAD CURRENT = 100mA TO 1A VIN = 1.2V, VOUT = 3.3V, COUT = 470µF, PULSE WIDTH = 416µs, LOAD CURRENT = 50mA TO 400mA Pin Description PIN NAME 1 REF 2 FB 3 POKIN FUNCTION Reference Output.
PAGE 8
MAX1703 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter UNDERVOLTAGE LOCKOUT OUT IC POWER PFM/PWM CONTROLLER 2.15V EN OUT START-UP OSCILLATOR D Q Q POUT P LXP ON ON REF 1.25V RDY FB OSC EN REF GND CLK/SEL LXN EN REFERENCE 300kHz OSCILLATOR OUT DUAL MODE/ FB Q PFM/PWM N MODE PGND FB COMPARATOR POKIN POK N REF MAX1703 AIN AO GAIN BLOCK N REF Figure 1.
PAGE 9
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter Table 2. Selecting the Operating Mode INPUT VOLTAGE (V) OUTPUT VOLTAGE (V) OUTPUT CURRENT (mA) CLK/SEL MODE FEATURES NO. OF CELLS 0 Low power Low supply current 1 NiCd/NiMH 1.2 3.3 600 1 PWM Low noise, high output current 2.4 3.3 1400 2.4 5.0 950 External Clock (200kHz to 400kHz) Synchronized PWM Low noise, high output current 3.6 5.0 1600 2 NiCd/NiMH 3 NiCd/NiMH MAX1703 Table 1.
PAGE 10
MAX1703 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter S POUT LOGIC HIGH D POUT Q FB P R P REF R LXP LXN Q S N ERROR COMPARATOR FB LXP LXN S Q N REF 2.7A TYP CURRENT LIMIT R PGND 800mA TYP CURRENT LIMIT OSC PGND Figure 3. Simplified PWM Controller Block Diagram Figure 4.
PAGE 11
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter Reference The MAX1703 has an internal 1.250V, 1% bandgap reference. Connect a 0.22µF bypass capacitor to GND within 0.2in. (5mm) of the REF pin. REF can source up to 50µA of external load current. Power-Good (POK) Comparator The MAX1703 gain block can function as a second comparator, or can be used to build a linear regulator using an external P-channel MOSFET pass device.
PAGE 12
MAX1703 1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter Table 3. Component Selection Guide PRODUCTION INDUCTORS Sumida CDR125 Surface Mount Sumida RCH654 series __________________Design Procedure Setting the Output Voltages Set the output voltage between 2.5V and 5.5V by connecting a resistor voltage-divider to FB from OUT to GND, as shown in Figure 2. The resistor values are then as follows: R1 = R2(VOUT / VFB - 1) where VFB, the boost-regulator feedback setpoint, is 1.24V.
PAGE 13
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter CON 4.7nF __________ Applications Information Intermittent Supply/Battery Connections When boosting an input supply connected via a mechanical switch, or a battery connected via spring contacts, input power may sometimes be intermittent as a result of contact bounce. When operating in PFM mode with input voltages greater than 2.
PAGE 14
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter MAX1703 ___________________Chip Information LX TRANSISTOR COUNT: 554 SUBSTRATE CONNECTED TO GND POUT MAX1703 LDOs MAX8865/MAX8866 PA µC RADIO Figure 8.
PAGE 15
1-Cell to 3-Cell, High-Power (1.5A), Low-Noise, Step-Up DC-DC Converter SOICN.
PAGE 16
MAX1703 1-Cell to 3-Cell, High-Power (1.