Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsInterface ICsInterface IC - transceivers RS232 5/3 SSOP 28

________________________________________________________________ Maxim Integrated Products 1

General Description

The MAX3238E/MAX3248E transceivers use Maxim’s

revolutionary AutoShutdown Plus™ feature to achieve

10nA supply current. These devices shut down the on-

board power supply and drivers when they do not sense

a valid signal transition on either the receiver or transmit-

ter inputs. This occurs if the RS-232 cable is disconnect-

ed or if the transmitters of the connected peripheral are

turned off. The devices turn on again when a valid transi-

tion is applied to any RS-232 receiver or transmitter input.

AutoShutdown Plus automatically achieves this power

savings through its on-board circuitry, as no changes are

required to the existing BIOS or operating system.

All RS-232 inputs and outputs, as well as the logic I/O

pins, have enhanced ESD protection to ±15kV. The addi-

tional ESD protection on the logic I/O pins makes the

MAX3238E/MAX3248E ideal for cell phone data cable

applications because it eliminates the need for costly

external TransZorb

™

or protection schemes.

The MAX3238E/MAX3248E contain five drivers and three

receivers and are 3V-powered EIA/TIA-232 and V.28/V.24

communication interfaces intended for cell phones, data

cables, and modem applications. A proprietary, high-effi-

ciency, dual charge-pump power supply and a low-

dropout transmitter combine to deliver true RS-232

performance from a single +3.0V to +5.5V supply. A

guaranteed data rate of 250kbps provides compatibility

with popular software for communicating with personal

computers.

The MAX3238E and the MAX3248E differ only in their

input logic thresholds. The MAX3238E has standard logic

thresholds, while the MAX3248E has low-level logic

thresholds of 0.6V to 1.2V, which are ideal for 1.8V sys-

tems.

The transmitter inputs, FORCEON, and FORCEOFF have

a 400kΩ active positive feedback resistor. Once driven to

a valid logic level, they will retain this level if the driving

signal is removed or goes high impedance. Unused

transmitter and logic inputs may be left unconnected. The

MAX3238E/MAX3248E can operate with supply voltages

ranging from +3.0V to +5.5V.

Applications

Features

♦ Enhanced ESD Protection on RS-232 I/O Pins and

All Logic Pins

±15kV—Human Body Model

±8kV—IEC 1000-4-2 Contact Discharge

±15kV—IEC 1000-4-2 Air-Gap Discharge

♦ Guaranteed Data Rate: 250kbps

♦ 10nA Low-Power Shutdown with Receivers Active

♦ Schmitt Triggers on All Inputs

♦ Flow-Through Pinout

♦ Meets EIA/TIA-232 Specifications Down to 3.0V

♦ Guaranteed 6V/µs Slew Rate

♦ Low-Level Logic Thresholds (MAX3248E)

♦ RS-232-Compatible Outputs to 2.7V

MAX3238E/MAX3248E

+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers

with ±15kV ESD-Protected I/O and Logic Pins

C1+

V+

C1-

T1IN

T2IN

INVALID

T3IN

R1OUT

R2OUT

T4IN

R3OUT

T5IN

R1OUTB

FORCEOFF

FORCEON

T5OUT

R3IN

T4OUT

R2IN

R1IN

T3OUT

T2OUT

T1OUT

V-

C2-

GND

C2+

SSOP

TOP VIEW

MAX3238E

MAX3248E

___________________Pin Configuration

19-1632; Rev 1; 6/01

Ordering Information

AutoShutdown Plus

s a trademark of Maxim Integrated Products.

TransZorb is a trademark of General Semiconductor Industries, Inc.

†

C4;

4,r

pg.

Cellular Data Cables

Modems

Battery-Powered Equipment

Peripherals

Data Cradles

Printers

Typical Operating Circuit appears at end of data sheet.

28 SSOP

PIN-PACKAGETEMP. RANGE

0°C to +70°C

-40°C to +85°C

0°C to +70°C

-40°C to +85°CMAX3248EEAI

MAX3248ECAI

MAX3238EEAI

MAX3238ECAI

PART

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.

Summary of content (14 pages)

PAGE 1
9-1632; Rev 1; 6/01 +3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins All RS-232 inputs and outputs, as well as the logic I/O pins, have enhanced ESD protection to ±15kV. The additional ESD protection on the logic I/O pins makes the MAX3238E/MAX3248E ideal for cell phone data cable applications because it eliminates the need for costly external TransZorb™ or protection schemes.
PAGE 2
MAX3238E/MAX3248E +3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins ABSOLUTE MAXIMUM RATINGS VCC ...........................................................................-0.3V to +6V V+ (Note 1) ...............................................................-0.3V to +7V V- (Note 1) ................................................................+0.3V to -7V V+ + |V-| (Note 1) .................................................................
PAGE 3
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins (VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and C2–C4 = 0.33µF (tested at 5.0V ±10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS Input Leakage Current T_IN, FORCEON, FORCEOFF (Note 2) Output Leakage Current Receivers disabled Output Voltage Low IOUT = 1.
PAGE 4
ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and C2–C4 = 0.33µF (tested at 5.0V ±10%), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS TIMING CHARACTERISTICS Maximum Data Rate RL = 3kΩ, CL = 1000pF, one transmitter switching Receiver Propagation Delay R_IN to R_OUT, CL = 150pF Receiver Output Enable Time Normal operation 2.
PAGE 5
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins SUPPLY CURRENT vs. SUPPLY VOLTAGE 50 40 SUPPLY CURRENT (mA) VOUT+ 1 TRANSMITTER 250kbps 4 TRANSMITTERS 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ +1000pF MAX3238E toc05 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 MAX3238E toc04 TRANSMITTER OUTPUT VOLTAGE (V) TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE 30 20 1 TRANSMITTER 250kbps 4 TRANSMITTERS 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ +1000pF 10 VOUT0 2.0 2.5 3.
PAGE 6
MAX3238E/MAX3248E +3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins Table 1.
PAGE 7
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins MAX3238E/MAX3248E POWER MANAGEMENT UNIT OR KEYBOARD CONTROLLER VCC FORCEOFF FORCEON INVALID PROTECTION DIODE MAX3238E/ MAX3248E PREVIOUS RS-232 VCC I Rx T1 5kΩ UART T2 Tx T3 CPU I/O CHIP WITH UART GND SHDN = GND T4 RS-232 T5 a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN. R1 VCC R2 TO µP R3 LOGIC TRANSITION DETECTOR I PROTECTION DIODE Figure 1.
PAGE 8
MAX3238E/MAX3248E +3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins Table 2. INVALID Truth Table +0.3V RS-232 SIGNAL PRESENT AT ANY RECEIVER INPUT INVALID OUTPUT Yes H R_IN 60µs TIMER R -0.3V No L Tables 1 and 2 and Figure 3 summarize the MAX3238E/ MAX2348Es’ operating modes. FORCEON and FORCEOFF override the automatic circuitry and force the transceiver into its normal operating state or into its lowpower standby state.
PAGE 9
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins INVALID HIGH RECEIVER INPUT LEVELS +2.7V INDETERMINATE +0.3V 0V INVALID LOW -0.3V INDETERMINATE -2.7V INVALID HIGH Figure 4a. Receiver Positive/Negative Thresholds for INVALID est, which is then discharged into the test device through a 1.5kΩ resistor. IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits.
PAGE 10
RC 1MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RD 1500Ω IP 100% 90% DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST Ir AMPERES 36.8% 10% 0 0 Figure 5a. Human Body ESD Test Model RC 50MΩ to 100MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) Cs 150pF TIME tRL tDL CURRENT WAVEFORM Figure 5b.
PAGE 11
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins 5V/div T2OUT MAX3238E/MAX3248E FORCEON = FORCEOFF +5V 0 T1IN +5V 0 T1OUT 2V/div -5V T1OUT +5V R1OUT 4µs/div 0 2µs/div VCC = 3.3V, C1–C4 = 0.1µF, CLOAD = 1000pF VCC = 3.3V, C1–C4 = 0.1µF, RLOAD = 3kΩ, CLOAD = 2500pF Figure 7. Transmitter Outputs when Recovering from Shutdown or Powering Up Figure 9.
PAGE 12
MAX3238E/MAX3248E +3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins + C1 0.1µF 28 25 27 C3 0.1µF 26 TVS SUBMINIATURE CONNECTOR C5 0.1µF C1+ C2+ C1- C2- V+ MAX3238E MAX3248E ±15kV ESD PROTECTION 1 C2 0.1µF 3 V- 4 C4 0.
PAGE 13
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins +3.3V 1µF 26 VCC 28 C1+ 0.1µF 0.1µF 0.1µF* MAX3238E MAX3248E V- 4 0.1µF 3 C224 T1IN T1 23 T2IN LOGIC INPUTS Data Cable Applications V+ 27 25 C11 C2+ T2 22 T3IN T3 19 T4IN T4 17 T5IN and Figure 10 shows the same test at 250kbps. For Figure 9, all transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF.
PAGE 14
________________________________________________________Package Information SSOP.EPS MAX3238E/MAX3248E +3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins 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.