Datasheet

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_______________General Description

The MAX3212 uses Maxim’s new proprietary Auto-

Shutdown mode to reduce supply current to 1µA. The

MAX3212, with 3 RS-232 drivers and 5 RS-232 receivers,

is intended for 2.7V to 3.6V-powered EIA/TIA-232E and

V.28/V.24 serial interface. True RS-232 levels are main-

tained across the operating range. A guaranteed data

rate of 235kbps provides compatibility with popular soft-

ware for communicating with personal computers.

Supply current is reduced to 1 µA with Maxim’s new

AutoShutdown feature. When the MAX3212 does not

sense a valid signal level on the receiver inputs, the on-

board power supply and drivers shut down. This occurs

if the RS-232 cable is disconnected or if the transmit-

ters of the connected peripheral are turned off. The sys-

tem turns on again when a valid level is applied to any

RS-232 receiver input. As a result, the system saves

power without changes to the existing software.

A second power-management feature is incorporated to

permit automatic shutdown when the RS-232 connection

is valid but inactive. In this case, a transition detector

facilitates shutdown when the receivers are presented

with stationary RS-232 levels for long periods.

Three-state drivers are provided on receiver outputs so

that multiple receivers, generally of different interface

standards, can be wire-ORed at the UART. The

MAX3212 is available in 28-pin SO and SSOP packages.

________________________Applications

Notebook and Palmtop Computers

Peripherals

Instruments

Battery-Powered Equipment

______________Ordering Information

____________________________Features

BETTER THAN BIPOLAR!

♦ 1µA Supply Current Using AutoShutdown

♦ Operates from Single +2.7V to +3.6V Supply

♦ 28-Pin SSOP or Wide SO Packages

♦ Meets All EIA/TIA-232E & EIA/TIA-562 Specifications

♦ Mouse Driveability–Guaranteed

♦ Low-Cost, Surface-Mount External Components

♦ 235kbps Guaranteed Data Rate–

LapLink™ Compatible

♦ +5V Logic Compatible

♦ Complementary Receiver Output Always Active

♦ Flow-Through Pinout

MAX3212*

+2.7V to +3.6V-Powered, 1µA Supply Current,

3-Driver/5-Receiver, True RS-232 Transceiver

________________________________________________________________

Maxim Integrated Products

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

PART

MAX3212CWI

MAX3212CAI 0°C to +70°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

28 Wide SO

28 SSOP

MAX3212EWI

MAX3212EAI -40°C to +85°C

-40°C to +85°C 28 Wide SO

28 SSOP

Pin Configuration appears at end of data sheet.

* ng

__________Typical Operating Circuit

R1IN

R2IN

R3IN

R4IN

R5IN

GND

T3OUT

T2OUT

T1OUT

R1OUT

R2OUT

R3OUT

R4OUT

R5OUT

R5OUTB

T3IN

T2IN

T1IN

+3.0V

0.33µF

0.68µF

1N6050

1N605015µH

0.33µF

V+ LN LP V-

FORCEON

TRAN

INVALID

FORCEOFF

MAX3212

327 1 216



284

+3.0V

AUTOSHUTDOWN OPERATION

FORCEOFF = HIGH, FORCEON = LOW

RS-232 Present

Yes

Status

On

Shut Down

19-0312; Rev 0; 9/94

Summary of content (12 pages)

PAGE 1
9-0312; Rev 0; 9/94 +2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver The MAX3212 uses Maxim’s new proprietary AutoShutdown mode to reduce supply current to 1µA. The MAX3212, with 3 RS-232 drivers and 5 RS-232 receivers, is intended for 2.7V to 3.6V-powered EIA/TIA-232E and V.28/V.24 serial interface. True RS-232 levels are maintained across the operating range.
PAGE 2
MAX3212 +2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver ABSOLUTE MAXIMUM RATINGS Supply Voltages VCC .....................................................................-0.3V to +4.6V V+ ............................................................(VCC - 0.3V) to +7.4V V- ........................................................................-7.4V to +2.0V LN ..............................................................-0.3V to (V+ + 1.0V) LP......................
PAGE 3
+2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver MAX3212 ELECTRICAL CHARACTERISTICS (continued) (VCC = 2.7V to 3.6V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS +25 V EIA/TIA-232E RECEIVERS Input Voltage Operating Range -25 Input Voltage Threshold Low 0.4 V Input Voltage Threshold High 3.0 Input Hysteresis 0.7 Input Resistance -15V < VIN < 15V 3 5 ±5.
PAGE 4
__________________________________________Typical Operating Characteristics (VCC = 3.3V, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. SUPPLY VOLTAGE TRANSMITTING SUPPLY CURRENT vs.
PAGE 5
+2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver PIN NAME 1 LN Inductor/Diode Connection Point FUNCTION 2 LP Inductor/Diode Connection Point 3 VCC Supply Voltage Input, 2.7V to 3.6V 4 EN Receiver Enable Control. Drive EN low to force receiver outputs into a high-Z state. Drive EN high for normal operation. Cycle EN high then low to reset TRAN. TRAN is always low when EN is high. 5 TRAN Transition Detection Output.
PAGE 6
MAX3212 +2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver not the absolute voltages. Increasing the size of C1 and C2 increases the time V+ and V- take to reach their final value. Bypass V CC to GND with at least 0.33 µF close to the MAX3212. Increase this to 4.7µF if there are no other V CC supply bypass components less than 6 inches (15cm) away from the MAX3212. Component suppliers are listed in Table 1.
PAGE 7
+2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver MAX3212 VCC POWER MANAGEMENT UNIT OR KEYBOARD CONTROLLER FORCEOFF FORCEON INVALID PREVIOUS RS-232 MAX3212 VCC CPU I/O CHIP WITH UART ESD PROTECTION DIODE Rx 5k UART RS-232 Tx SHDN = LOW GND a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN. VCC Figure 1.
PAGE 8
MAX3212 +2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver +0.3V to +3.0V + FORCEOFF POWER DOWN + -0.3V to -3.0V FORCEON RIN_ Rx ROUT_ EN • • • • • 30µs DELAY INVALID • INVALID IS AN INTERNALLY GENERATED SIGNAL THAT IS USED BY THE AUTOSHUTDOWN LOGIC AND APPEARS AS AN OUTPUT OF THE DEVICE. POWER DOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES.
PAGE 9
+2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver +0.3V 0V MASTER SHDN LINE 0.1µF INDETERMINATE MAX3212 POWER MANAGEMENT UNIT TRANSMITTERS ENABLED, INVALID HIGH +3.0V 1M AUTOSHUTDOWN, TRANSMITTERS DISABLED, 1µA SUPPLY CURRENT, INVALID LOW -0.3V FORCEOFF FORCEON INDETERMINATE MAX3212 -3.0V TRANSMITTERS ENABLED, INVALID HIGH (a) Figure 5.
PAGE 10
+2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver MAX3212 Driving the MAX3212 from 5V Logic The MAX3212 can directly interface with various 5V logic families, including ACT and HCT CMOS. TRANSMITTER OUTPUT VOLTAGE vs. LOAD CURRENT PER TRANSMITTER Mouse Driveability MAX3212-06 TRANSMITTER OUTPUT VOLTAGE (V) 7 T1OUT AND T2OUT 5 The MAX3212 has been specifically designed to power serial mice while operating from low-voltage power supplies.
PAGE 11
+2.7V to +3.
PAGE 12
MAX3212 +2.7V to +3.6V-Powered, 1µA Supply Current, 3-Driver/5-Receiver, True RS-232 Transceiver ________________________________________________________Package Information DIM A A1 B C D E e H L α α E H C L INCHES MILLIMETERS MIN MAX MAX MIN 0.068 0.078 1.73 1.99 0.002 0.05 0.21 0.008 0.010 0.38 0.015 0.25 0.004 0.09 0.20 0.008 SEE VARIATIONS 0.205 5.20 5.38 0.209 0.0256 BSC 0.65 BSC 0.301 7.65 7.90 0.311 0.025 0.95 0.037 0.