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General Description

The MAX3322E/MAX3323E 3.0V to 5.5V powered

EIA/TIA-232 and V.28/V.24 communications interfaces

are designed for multidrop applications with low power

requirements, high data-rate capabilities, and

enhanced electrostatic discharge (ESD) protection. All

RS-232 inputs and outputs are protected to ±15kV

using the IEC 1000-4-2 Air-Gap Discharge method,

±8kV using the IEC 1000-4-2 Contact Discharge

method, and ±15kV using the Human Body Model.

The MAX3322E/MAX3323E have pin-selectable

5kΩ/high-impedance RS-232 receivers. These devices

are capable of receiving data in high-impedance mode.

In multidrop applications, one receiver has a 5kΩ input

resistance, while the other receivers are high imped-

ance to ensure the RS-232 standard is observed. Logic

control permits selection of the functional mode: high

impedance or RS-232 standard load. The transmitters

are enabled by logic control to allow the multiplexing of

the inputs to a single UART.

A proprietary low-dropout transmitter output stage

enables true RS-232 performance from a 3.0V to 5.5V

supply with a dual charge pump. The charge pump

requires only four small 0.1µF capacitors for operation

from a 3.3V supply. The MAX3322E/MAX3323E are

capable of running at data rates up to 250kbps while

maintaining RS-232-compliant output levels. The

MAX3322E/MAX3323E have a unique V

pin that allows

operation in mixed-logic voltage systems. Both input

and output logic levels are pin programmable through

the V

pin.

The MAX3322E is a 2Tx/2Rx device for hardware hand-

shaking in standard RS-232 mode, and the MAX3323E

is a 1Tx/1Rx, required in most multidrop applications.

The MAX3322E is offered in a space-saving TSSOP

package. The MAX3323E is offered in 16-pin DIP and

space-saving TSSOP packages.

Applications

Bar-Code Scanners

Video Security

Industrial Data Acquisition

Data Splitters

Features

♦ Pin-Selectable 5kΩ/High-Impedance Receivers

♦ Transmitter Outputs Three-Stated by Logic

Control

♦ V

Pin for Compatibility with Mixed Voltage

Systems

♦ 1Tx/1Rx (MAX3323E) or 2Tx/2Rx (MAX3322E)

Versions

♦ 250kbps Data Rate

♦ 1µA Low-Power Shutdown

♦ High ESD Protection for RS-232 I/O Pins

±15kV—Human Body Model

±8kV—IEC 1000-4-2 Contact Discharge

±15kV—IEC 1000-4-2 Air-Gap Discharge

MAX3322E/MAX3323E

±15kV ESD-Protected, RS-232 Transceivers for

Multidrop Applications

________________________________________________________________ Maxim Integrated Products 1

GND

SHDN

C2+

C1-

V+

C1+

TOP VIEW

RENABLE

TXENABLE

TIN2

ROUT2RIN2

TOUT2

V-

C2-

TIN1

ROUT1RIN1

TOUT1

MAX3322E

TSSOP

Pin Configurations

Ordering Information

19-2667; Rev 1; 1/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART TEMP RANGE

PIN-PACKAGE

MAX3322E EUP -40°C to +85°C 20 TSSOP

MAX3323E EUE -40°C to +85°C 16 TSSOP

MAX3323EEPE -40°C to +85°C 16 DIP

Pin Configurations continued at end of data sheet.

Typical Operating Circuit and Functional Diagram appear

at end of data sheet.

Summary of content (13 pages)

PAGE 1
9-2667; Rev 1; 1/03 ±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications The MAX3322E/MAX3323E 3.0V to 5.5V powered EIA/TIA-232 and V.28/V.24 communications interfaces are designed for multidrop applications with low power requirements, high data-rate capabilities, and enhanced electrostatic discharge (ESD) protection.
PAGE 2
MAX3322E/MAX3323E ±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications ABSOLUTE MAXIMUM RATINGS All Voltages Referenced to GND VCC, VL ....................................................................-0.3V to +6V V+ (Note 1) ....................................................(VCC - 0.3V) to +7V V- (Note 1) ................................................................+0.3V to -7V V+ + |V-| (Note 1) .................................................................
PAGE 3
±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications (VCC = 3.0V to 5.5V, VL = 1.65V to 5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2 = C3 = C4 = 0.33µF, tested at +5V ±10%; TA = TMIN to TMAX. Typical values are at VCC = VL = 3.3V and TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL Input Threshold High CONDITIONS MIN TYP MAX VL = 1.65V 1 1.4 VL = 3.3V 1.5 2.4 VL = 5.0V 1.8 2.4 Input Hysteresis 0.
PAGE 4
Typical Operating Characteristics (VCC = 3.3V, VL = 3.3V, C1–C4 = 0.1µF, TA = +25°C.) SLEW RATE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 2.5 15 SLEW RATESLEW RATE (V/µs) DATA RATE = 250kbps LOAD = 3kΩ IN PARALLEL WITH CL 0 MAX3322E toc02 5.0 OUTPUT VOLTAGE (V) 18 MAX3322E toc01 7.5 -2.5 12 9 SLEW RATE+ 6 3 -5.0 0 -7.5 0 0 1000 2000 3000 4000 1000 5000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) TRANSMITTER OUTPUT VOLTAGE vs.
PAGE 5
±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications PIN NAME FUNCTION MAX3322E MAX3323E 1 1 C1+ 2 2 V+ +5.5V Generated by the Charge Pump 3 3 C1- Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor 4 4 C2+ Positive Terminal of the Inverting Charge-Pump Capacitor 5 5 C2- 6 6 V- 7, 9 7 TOUT_ Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor Negative Terminal of the Inverting Charge-Pump Capacitor -5.
PAGE 6
MAX3322E/MAX3323E ±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications +3V +3V 0V INPUT 50% 50% 50% INPUT 0V V+ 0V V- OUTPUT tPLH tPHL Figure 1. Transmitter Propagation-Delay Timing POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER 50% OUTPUT VCC GND tPLH tPHL Figure 2. Receiver Propagation-Delay Timing ing capacitor (C1, C2) and reservoir capacitor (C3, C4) to generate the V+ and V- supplies. Because supply voltages can vary from +3V up to +5.
PAGE 7
±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications TXENABLE RENABLE SHDN TRANSMITTER OUTPUT RECEIVER OUTPUT RECEIVER INPUT 1 1 0 High-Z High-Z High-Z 1 1 1 Active Enabled 5kΩ 1 0 0 High-Z High-Z High-Z 1 0 1 Active Enabled High-Z 0 1 0 High-Z High-Z High-Z 0 1 1 High-Z Enabled 5kΩ 0 0 0 High-Z High-Z High-Z 0 0 1 High-Z Enabled High-Z 5V/div T2 2V/div T1 VCC = 3.3V C1–C4 = 0.1µF 50µs/div Figure 4.
PAGE 8
RC 1MΩ CHARGE-CURRENTLIMIT RESISTOR RD 1.5kΩ IP 100% 90% DISCHARGE RESISTANCE Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES HIGHVOLTAGE DC SOURCE Cs 100pF STORAGE CAPACITOR DEVICE UNDER TEST 36.8% 10% 0 0 Figure 5. Human Body ESD Test Model IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not refer specifically to integrated circuits.
PAGE 9
±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications When using the minimum required capacitor values, make sure the capacitor value does not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor’s equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-. Table 2. Minimum Required Capacitor Values VCC (V) C1 (µF) C2, C3, C4 (µF) 3.0 to 3.6 0.1 0.1 4.5 to 5.5 0.
PAGE 10
MAX3322E/MAX3323E ±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications MAX3322E fig11 +3.3V T1IN 5V/div 0.1µF SHDN C1 0.1µF 3 C14 C2 0.1µF VCC 1 C1+ V+ 2 C3 0.1µF MAX3323E C2+ V- 5 C2- T1OUT 5V/div 6 C4 0.1µF R1OUT 5V/div VCC = 3.3V T_OUT T_IN 2µs/div 1000pF R_IN R_OUT Figure 11. Loopback Test Results at 125kbps 5kΩ MAX3322E fig12 T1IN 5V/div GND T1OUT 5V/div Figure 10. Loopback Test Circuit Power-Supply Decoupling In most circumstances, a 0.
PAGE 11
±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications TOP VIEW +3.3V 18 SHDN C1 0.1µF 4 C2 0.1µF 20 17 VCC 1 C1+ 3 C1- TXENABLE RENABLE VL V+ MAX3322E C2+ V- T1OUT C4 0.1µF 7 V+ 2 15 GND 14 SHDN MAX3323E 13 VL C2- 5 12 RENABLE V- 6 11 TXENABLE 10 TIN1 TOUT1 7 9 RIN1 8 9 T2OUT 14 T2IN 16 VCC C2+ 4 6 5 C2- C1+ 1 C1- 3 2 C3 0.
PAGE 12
MAX3322E/MAX3323E ±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.
PAGE 13
±15kV ESD-Protected, RS-232 Transceivers for Multidrop Applications 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.