Datasheet

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General Description

The MAX3120 IrDA 1.2-compatible infrared transceiver

is optimized for battery-powered, space-constrained

applications. It consumes only 120µA while supporting

data rates up to 115kbps over a wide 3V to 5.5V oper-

ating range, and features a 10nA shutdown mode to

further extend battery life.

The MAX3120 reduces the space required for IrDA

applications by requiring a minimum of external compo-

nents: photodiode, infrared LED, and current-setting

resistor. Optical components are external to allow maxi-

mum flexibility in PC board design. The MAX3120 is

available in 8-pin µMAX and SO packages. The µMAX

package consumes half the board space of an 8-pin

SO.

Applications

IrDA Applications

Personal Digital Assistants (PDAs)

Palmtop Computers

Cell Phones

Hand-Held Equipment

Peripherals

Features

♦ IrDA 1.2 Compatible: 2.4kbps to 115.2kbps

♦ +3V to +5.5V Single-Supply Operation

♦ Flexible Optics Selection and Layout

♦ 120µA Supply Current

♦ 10nA Shutdown Supply Current

♦ 200mA, High-Current Infrared LED Drive

MAX3120

Low-Profile, 3V, 120µA,

IrDA Infrared Transceiver

________________________________________________________________

Maxim Integrated Products

RXD

LEDC

PGND

SHDNPINC

GND

TXD

MAX3120

µMAX/SO

TOP VIEW

19-1390; Rev 0; 10/98

PART

MAX3120CUA

MAX3120CSA

MAX3120EUA -40°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

8 µMAX

8 SO

8 µMAX

Pin Configuration

Ordering Information

MAX3120ESA -40°C to +85°C 8 SO

MAX3120

RXD PINC

LEDC

TXD

+3.3V

SHDN

GND PGND

MAX3100

SCLK

DIN

DOUT

GND

DIODE

LED

Typical Operating Circuit

Summary of content (8 pages)

PAGE 1
9-1390; Rev 0; 10/98 Low-Profile, 3V, 120µA, IrDA Infrared Transceiver The MAX3120 IrDA 1.2-compatible infrared transceiver is optimized for battery-powered, space-constrained applications. It consumes only 120µA while supporting data rates up to 115kbps over a wide 3V to 5.5V operating range, and features a 10nA shutdown mode to further extend battery life.
PAGE 2
MAX3120 Low-Profile, 3V, 120µA, IrDA Infrared Transceiver ABSOLUTE MAXIMUM RATINGS (Referred to GND) VCC ...........................................................................-0.3V to +6V TXD, SHDN, LEDC ...................................................-0.3V to +6V RXD ............................................................-0.3V to (VCC + 0.3V) PGND ....................................................................-0.1V to +0.1V PINC............................................................
PAGE 3
Low-Profile, 3V, 120µA, IrDA Infrared Transceiver MAX3120 ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.0V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C and VCC = +3.3V.) PARAMETER SYMBOL IR TRANSMITTER Transmitter Rise Time Transmitter Fall Time CONDITIONS tr tf MIN 10% to 90% of 200mA drive current 90% to 10% of 200mA drive current VCC = 3.3V IOUT = 200mA VCC = 5.0V Transmitter Output Resistance Off-Leakage Current TYP MAX UNITS 20 20 1.15 0.9 0.
PAGE 4
Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) AMBIENT PHOTODIODE CURRENT REJECTION vs. SUPPLY VOLTAGE 300 250 200 150 100 4.0 60 40 20 MAX3120 TOC07 80 RXD PULSE WIDTH (µs) 350 TRANSMITTER POWER = 200mW/sr INPUT PULSE WIDTH = 78µs TEMIC BPV22NF VCC = 3.3V 3.5 RXD PULSE WIDTH (µs) 100 MAX3120 TOC06 400 RXD OUTPUT PULSE WIDTH vs. DISTANCE RXD OUTPUT PULSE WIDTH vs.
PAGE 5
Low-Profile, 3V, 120µA, IrDA Infrared Transceiver RXD OUTPUT vs. INFRARED INPUT RXD OUTPUT vs. INFRARED INPUT MAX3120 toc12 2V/div RXD OUTPUT 2V/div INFRARED INPUT MAX3120 toc13 2V/div RXD OUTPUT 2V/div INFRARED INPUT 100µs/div VCC = 3.3V, 2400bps AT 1m DISTANCE, TERMIC BPV22NF, TRANSMIT POWER 200mW/sr 2µs/div VCC = 3.3V, 115.2kbps AT 1m DISTANCE, TERMIC BPV22NF, TRANSMIT POWER 200mW/sr Pin Description PIN NAME 1 TXD IR Transmitter TTL/CMOS Data Input. High = LED on.
PAGE 6
MAX3120 Low-Profile, 3V, 120µA, IrDA Infrared Transceiver RXD TXD IPIN = (4µW/cm2 )(0.075cm2 )(1.8)(0.95)2 (0.6A/W) LEDC = 291nA PGND BANDPASS FILTER PINC + GND BIAS MAX3120 SHDN 1.2V VCC Figure 1. Functional Diagram Transmitter The MAX3120’s IR transmitter consists of a high-power MOS switch, capable of quickly switching 200mA with less than 2Ω of on-resistance. Internal buffering keeps the input capacitance of the TXD pin extremely low to ease the input drive requirement.
PAGE 7
Low-Profile, 3V, 120µA, IrDA Infrared Transceiver MAX3120 Power Dissipation = ISET · VLEDC · Duty Cycle IR LED Power Dissipation = ISET · VLED · Duty Cycle RSET Power Dissipation = ISET2 · RSET · Duty Cycle Power-Supply Noise Rejection Because of the extremely sensitive nature of photodiode amplifiers, it is important to maintain a quiet supply voltage. Use a separate analog supply voltage where possible. Place a 1µF ceramic bypass capacitor as close to the VCC pin as possible.
PAGE 8
Low-Profile, 3V, 120µA, IrDA Infrared Transceiver SOICN.EPS MAX3120 Package Information (continued) 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.