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General Description

The MAX1832–MAX1835 are high-efficiency step-up

converters with complete reverse battery protection that

protects the device and the load when the battery is

reversed. They feature a built-in synchronous rectifier,

which allows for over 90% efficiency and reduces size

and cost by eliminating the need for an external

Schottky diode.

These step-up converters operate from a +1.5V to

+5.5V input voltage range and deliver up to 150mA of

load current. The MAX1833/MAX1835 have a fixed

+3.3V output, and the MAX1832/MAX1834 have

adjustable outputs from +2V to +5.5V. In shutdown, the

MAX1832/MAX1833 connect the battery input to the

voltage output, allowing the input battery to be used as

a backup or real-time clock supply when the converter

is off (see Selector Guide).

The MAX1832–MAX1835 are available in a miniature 6-

pin SOT23 package. The MAX1832EVKIT is available to

shorten the design cycle.

________________________Applications

Medical Diagnostic Equipment

Pagers

Hand-Held Instruments

Remote Wireless Transmitters

Digital Cameras

Cordless Phones

Battery Backup

PC Cards

Local 3.3V or 5V Supply

Features

♦ Reverse Battery Protection for DC-DC Converter

and Load

♦ Up to 90% Efficiency

♦ No External Diode or FETs Needed

♦ Internal Synchronous Rectifier

♦ 4µA Quiescent Current

♦ <1µA Shutdown Supply Current

♦ +1.5V to +5.5V Input Voltage Range

♦ Accurate SHDN Threshold for Low-Battery Cutoff

♦ BATT Connected to OUT in Shutdown for Backup

Power (MAX1832/MAX1833)

♦ RST Output (MAX1833/MAX1835)

♦ Fixed +3.3V Output Voltage (MAX1833/MAX1835)

♦ Adjustable Output Voltage (MAX1832/MAX1834)

♦ Up to 150mA Output Current

♦ Tiny 6-Pin SOT23 Package

MAX1832–MAX1835

High-Efficiency Step-Up Converters with

Reverse Battery Protection in SOT23-6

________________________________________________________________ Maxim Integrated Products 1

BATT

LXGND

16FB

5 OUT

SHDN

MAX1832

MAX1834

SOT23-6

TOP VIEW

BATT

LXGND

16RST

5 OUT

SHDN

MAX1833

MAX1835

SOT23-6

Pin Configurations

19-1802; Rev 0; 10/00

EVALUATION KIT AVAILABLE

Ordering Information

PART T EM P. R A N G E

PIN-

PACKAGE

TOP

MARK

MAX1832EUT-T -40°C to +85°C 6 SOT23-6 AAOT

MAX1833EUT-T -40°C to +85°C 6 SOT23-6 AAOU

MAX1834EUT-T -40°C to +85°C 6 SOT23-6 AAOV

MAX1835EUT-T -40°C to +85°C 6 SOT23-6 AAOW

Selector Guide

PART

OUTPUT

VOLTAGE

OUTPUT VOLTAGE

IN SHUTDOWN

MAX1832EUT-T Adjustable V

BATT

MAX1833EUT-T Fixed 3.3V V

BATT

MAX1834EUT-T Adjustable V

BATT

- 0.7V

MAX1835EUT-T Fixed 3.3V V

BATT

- 0.7V

Note: Requires special solder temperature profile described in

the Absolute Maximum Ratings.

Summary of content (10 pages)

PAGE 1
9-1802; Rev 0; 10/00 ILABLE N KIT AVA EVALUATIO High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 Features ♦ Reverse Battery Protection for DC-DC Converter and Load ♦ Up to 90% Efficiency ♦ No External Diode or FETs Needed ♦ Internal Synchronous Rectifier ♦ 4µA Quiescent Current ♦ <1µA Shutdown Supply Current ♦ +1.5V to +5.
PAGE 2
MAX1832–MAX1835 High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 ABSOLUTE MAXIMUM RATINGS BATT, LX to GND.........................................................-6V to +6V LX to OUT ....................................................................-6V to +1V SHDN to GND..............................................-6V to (VOUT + 0.3V) OUT, FB, RST TO GND ............................................-0.3V to +6V LX Current ......................................................
PAGE 3
High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 (V SHDN = +1.5V, VOUT = +3.3V, VBATT = +2V, GND = 0, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0 10 µA 1.8 5.0 Reverse Battery Current into OUT VOUT = 0, VBATT = V SHDN = VLX = -3V Quiescent Current into BATT VOUT = +3.5V, VFB = +1.3V Shutdown Current into BATT VOUT = +3.5V, VBATT = +2V, V SHDN = 0 0.
PAGE 4
Typical Operating Characteristics (VOUT = +3.3V, VBATT = +2V, unless otherwise noted.) (Figure 1) EFFICIENCY vs. LOAD CURRENT (VOUT = 3.3V) VBATT = +2.7V 75 VSHDN = VBATT R1 = 309Ω R2 = 100kΩ MAX1834 VBATT = +1.5V 85 1 10 100 VBATT = +1.5V VSHDN = VBATT R1 = 100kΩ R2 = 100kΩ CIN = 20µF COUT = 20µF MAX1834 75 VSHDN = VBATT MAX1835 75 0.1 80 80 65 1000 70 0.1 1 10 100 1000 0.1 1 10 10 100 ILOAD (mA) ILOAD (mA) ILOAD (mA) MAXIMUM OUTPUT CURRENT vs.
PAGE 5
High-Efficiency Step-Up Converters with Reverse Battery Protection in a SOT23-6 ON/OFF RESPONSE LOAD TRANSIENT MAX1832/35 toc10 MAX1832/35 toc11 VBATT 1V/div VOUT 100mV/div VOUT 1V/div ILOAD 100mA/div 0 2ms/div VSHDN = VBATT = 2.0V, RLOAD = 22Ω, VOUT = 3.3V 40µs/div RLOAD = 22Ω TO 200Ω, VOUT = +3.3V, VBATT = +2.0V SHUTDOWN RESPONSE LINE TRANSIENT MAX1832/35 toc13 MAX1832/35 toc12 VSHDN 1V/div VBATT 500mV/div 0 VOUT 1V/div VOUT 50mV/div 0 MAX1833 40µs/div RLOAD = 22Ω, VBATT = 3.3V, VBATT = 2.
PAGE 6
High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 MAX1832–MAX1835 Pin Description PIN MAX1832 MAX1834 NAME MAX1833 MAX1835 FUNCTION 1 1 SHDN Shutdown. A high logic level turns on the device. When SHDN is low the part is off, and the current into BATT is typically 0.1µA. For the MAX1832/MAX1833, the battery is connected to OUT through an internal PFET and the external inductor when SHDN is low. SHDN can be used for low-battery cutoff (1.228V threshold).
PAGE 7
High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 The MAX1832–MAX1835 compact, high-efficiency step-up converters feature 4µA quiescent supply current to ensure the highest possible efficiency over a wide load range. With a minimum +1.5V input voltage, these devices are well suited for applications with two alkaline cells, two nickel-metal-hydride (NiMH) cells, or one lithium ion (Li+) cell.
PAGE 8
MAX1832–MAX1835 High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 OUT STARTUP CIRCUITRY ZEROCROSSING DETECTOR MAX1832 MAX1834 P SHDN CONTROL LOGIC LX DRIVER FB N ERROR COMPARATOR BATT REVERSE BATTERY N PROTECTION MOSFET CURRENT LIMIT 1.228V GND Figure 2. MAX1832/MAX1834 Simplified Functional Diagram OUT MAX1833 MAX1835 STARTUP CIRCUITRY ZEROCROSSING DETECTOR P CONTROL LOGIC N 1.
PAGE 9
High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 Table 1. Suggested Inductors and Suppliers MANUFACTURER INDUCTOR PHONE Coilcraft DS1608C-103 DO1606T-103 847-639-6400 Sumida CDRH4D18-100 CR43-100 847-956-0666 Murata LQH4N100K 814-237-1431 Power-On Reset The MAX1833/MAX1835 provide a power-on reset output (RST). A 100kΩ to 1MΩ pullup resistor from RST to OUT provides a logic control signal.
PAGE 10
MAX1832–MAX1835 High-Efficiency Step-Up Converters with Reverse Battery Protection in SOT23-6 6LSOT.EPS Package Information Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.