Datasheet

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_______________General Description

The MAX218 RS-232 transceiver is intended for battery-

powered EIA/TIA-232E and V.28/V.24 communications

interfaces that need two drivers and two receivers with

minimum power consumption. It provides a wide +1.8V

to +4.25V operating voltage range while maintaining

true RS-232 and EIA/TIA-562 voltage levels. The

MAX218 runs from two alkaline, NiCd, or NiMH cells

without any form of voltage regulator.

A shutdown mode reduces current consumption to

1µA, extending battery life in portable systems. While

shut down, all receivers can remain active or can be

disabled under logic control, permitting a system incor-

porating the CMOS MAX218 to monitor external

devices while in low-power shutdown mode.

A guaranteed 120kbps data rate provides compatibility

with popular software for communicating with personal

computers. Three-state drivers are provided on all

receiver outputs so that multiple receivers, generally of

different interface standards, can be wire-ORed at the

UART. The MAX218 is available in 20-pin DIP, SO, and

SSOP packages.

________________________Applications

Battery-Powered Equipment

Computers

Printers

Peripherals

Instruments

Modems

____________________________Features

BETTER THAN BIPOLAR!

♦ Operates Directly from Two Alkaline, NiCd,

or NiMH Cells

♦ +1.8V to +4.25V Supply Voltage Range

♦ 120kbps Data Rate

♦ Low-Cost Surface-Mount Components

♦ Meets EIA/TIA-232E Specifications

♦ 1µA Low-Power Shutdown Mode

♦ Both Receivers Active During Low-Power Shutdown

♦ Three-State Receiver Outputs

♦ Flow-Through Pinout

♦ On-Board DC-DC Converters

♦ 20-Pin SSOP, Wide SO, or DIP Packages

______________Ordering Information

*Contact factory for dice specifications.

MAX218

1.8V to 4.25V-Powered,

True RS-232 Dual Transceiver

________________________________________________________________

Maxim Integrated Products

GND

V+

C1+

GND

SHDN

N.C.

TOP VIEW

C1-

V-

T1OUT

T2OUT

T2IN

T1IN

GND

R1IN

R2IN

R2OUT

R1OUT

DIP/SO/SSOP

MAX218

__________________Pin Configuration

T1OUT

T2OUT

T1IN

T2IN

R1OUT

R2OUT

R1IN

R2IN

GND

SHDN

C1+

C1-

V-

5, 17, 20

MAX218

ENABLE

ON/OFF

1.8V

TO

4.25V

V+

__________Typical Operating Circuit

Call toll free 1-800-998-8800 for free samples or literature.

19-0246; Rev 1; 7/95

PART TEMP. RANGE

MAX218CPP 0°C to +70°C

MAX218C/D 0°C to +70°C Dice*

20 Plastic DIP

PIN-PACKAGE

MAX218CAP 0°C to +70°C 20 SSOP

MAX218EPP -40°C to +85°C

MAX218EAP -40°C to +85°C 20 SSOP

20 Plastic DIP

MAX218EWP -40°C to +85°C 20 Wide SO

MAX218CWP 0°C to +70°C 20 Wide SO

Summary of content (8 pages)

PAGE 1
9-0246; Rev 1; 7/95 1.8V to 4.
PAGE 2
MAX218 1.8V to 4.25V-Powered, True RS-232 Dual Transceiver ABSOLUTE MAXIMUM RATINGS Supply Voltages VCC ....................................................................-0.3V to +4.6V V+ .......................................................... (VCC - 0.3V) to +7.5V V- .......................................................................+0.3V to -7.4V VCC to V- ..........................................................................+12V LX ...........................................................
PAGE 3
1.8V to 4.25V-Powered, True RS-232 Dual Transceiver (Circuit of Figure 1, VCC = 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3.0V, TA = +25°C.
PAGE 4
__________________________________________Typical Operating Characteristics (Circuit of Figure 1, VCC = 1.8V, all transmitter outputs loaded with 3kΩ, TA = +25°C, unless otherwise noted.) TRANSMITTING SUPPLY CURRENT vs. LOAD CAPACITANCE SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (mA) VCC = 2.
PAGE 5
1.8V to 4.25V-Powered, True RS-232 Dual Transceiver 6 1µF C4 V+ LX V- VCC C1+ MAX218 ON/OFF 3 SHDN C1- 7 T1IN 16 1µF C3 0.47µF C1 R2IN 11 R2 EN GND 4 Switch-Mode Power Supply The switch-mode power supply uses a single inductor with one diode and three small capacitors to generate ±6.5V from an input voltage in the 1.8V to 4.25V range. R1IN 12 R1 10 R2OUT 18 T2OUT 13 T2 9 R1OUT 15 T1OUT 14 T1 8 T2IN ENABLE 1µF C2 19 1 1.8V TO 4.
PAGE 6
MAX218 1.8V to 4.25V-Powered, True RS-232 Dual Transceiver Table 1.
PAGE 7
1.8V to 4.25V-Powered, True RS-232 Dual Transceiver 3V DC-DC CONVERTER MAX878 OR MAX756 OR MAX856 1µF C5 6 V- MAX218 3 SHDN C1+ C1- 7 T1IN R1 10 R2OUT R2 EN 4 18 16 1µF C3 0.47µF C1 T2OUT 13 T2 9 R1OUT 15 T1OUT 14 T1 8 T2IN ENABLE V+ VCC 0.1µF C4 ON/OFF 1µF C2 19 1 LX R1IN 12 R2IN 11 GND 5, 17, 20 Figure 2. Operating from Unregulated and Regulated Supplies Low-Power Operation The following suggestions will help you get maximum life out of your batteries.
PAGE 8
MAX218 1.8V to 4.25V-Powered, True RS-232 Dual Transceiver ______3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim PART No. OF SUPPLY No. OF RECEIVERS VOLTAGE TRANSMITTERS/ ACTIVE IN (V) RECEIVERS SHUTDOWN GUARANTEED DATA RATE (kbps) EIT/TIA232 OR 562 MAX212 3.0 to 3.6 3/5 5 120 232 MAX3212 2.7 to 3.6 3/5 5 120 232 MAX218 FEATURES Drives mice AutoShutdown, complementary receiver, drives mice, transient detection Operates directly from a battery without a voltage regulator 1.