Maxim MAX3218CAP, MAX3218EAP, MAX3218CPP, MAX3218C-D, MAX3218EPP Datasheet

19-0380; Rev 0; 3/95

1µA Supply Current, 1.8V to 4.25V-Powered

RS-232 Transceiver with AutoShutdown™

_______________General Description

The MAX3218 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 from a single lowvoltage supply. It provides a wide +1.8V to +4.25V operating voltage range while maintaining true RS-232 and EIA/TIA-562 voltage levels. The MAX3218 runs from two alkaline, NiCd, or NiMH cells without any form of voltage regulator. A guaranteed 120kbps data rate provides compatibility with popular software for communicating with personal computers.

Supply current is reduced to 1µA with Maxim’s new AutoShutdown™ feature. When the MAX3218 does not sense a valid signal level on the receiver inputs, the onboard power-supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the connected peripheral are turned off. The system turns on again when a valid level is applied to either RS-232 receiver input. As a result, the system saves power without changes to the existing software. Additionally, the MAX3218 can be forced into or out of shutdown, under logic control.

While shut down, all receivers can remain active or can be disabled under logic control, permitting a system incorporating the CMOS MAX3218 to monitor external devices while in low-power shutdown. Three-state drivers are provided on both receiver outputs so that multiple receivers, generally of different interface standards, can be on the same bus. The MAX3218 is available in 20-pin DIP and SSOP packages.

____________________________Features

BETTER THAN BIPOLAR!

♦ 1µA Supply Current Using AutoShutdown™ ♦ Operates Directly from Two Alkaline,

NiCd or NiMH Cells

♦ +1.8V to +4.25V Single-Supply Voltage Range ♦ 120kbps Data Rate Guaranteed ♦ Low-Cost Surface-Mount Components ♦ Meets EIA/TIA-232E Specifications ♦ Three-State Receiver Outputs ♦ Flow-Through Pinout ♦ On-Board DC-DC Converters ♦ 20-Pin SSOP and DIP Packages

______________Ordering Information

PART

MAX3218CPP MAX3218CAP 0°C to +70°C MAX3218C/D MAX3218EPP -40°C to +85°C MAX3218EAP -40°C to +85°C 20 SSOP

†

Contact factory for dice specifications.

TEMP. RANGE PIN-PACKAGE

0°C to +70°C

0°C to +70°C Dice

20 Plastic DIP 20 SSOP

†

20 Plastic DIP

MAX3218*

________________________Applications

__________________Pin Configuration

Battery-Powered Equipment Subnotebook Computers PDAs Hand-Held Equipment Peripherals Cellular Phones

* Patent Pending ™ AutoShutdown is a trademark of Maxim Integrated Products.

________________________________________________________________

TOP VIEW

INVALID

FORCEON

FORCEOFF

GND

V T1IN T2IN

R1OUT R2OUT

1 2 3 4

MAX3218

5 6

7 8 9

DIP/SSOP

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

GND

V+

C1+

GND

C1-

V-

T1OUT

T2OUT

R1IN

R2IN

Maxim Integrated Products

1µA Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdown™

ABSOLUTE MAXIMUM RATINGS

Supply Voltages

....................................................................-0.3V to +4.6V

V+.......................................................... (V

V-.......................................................................+0.3V to -7.4V

to V-..........................................................................+12V

LX ................................................................-0.3V to (1V + V+)

Input Voltages

T_IN, FORCEON, FORCEOFF

R_IN.................................................................................±25V

MAX3218

Output Voltages

T_OUT.............................................................................±15V)

R_OUT....................................................-0.3V to (V

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

............................ -0.3V to +7V

- 0.3V) to +7.5V

+ 0.3V)

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, VCC= 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA= T Typical values are at V

DC CHARACTERISTICS

Supply Current, Shutdown µA Supply Current,

AutoShutdown™ Disabled

LOGIC INPUTS AND RECEIVER OUTPUTS

Input Logic Threshold Low Input Logic Threshold High

AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)

Receiver Input Thresholds, Transmitters Enabled

Receiver Input Thresholds Transmitters Disabled

INVALID Output Low Voltage 0.4 INVALID Output High Voltage V

= 3.0V, TA= +25°C.)

VCC= 3.0V, TA= +25°C, all R_IN open, FORCEON = GND, FORCEOFF = V

FORCEOFF = GND, TA= +25°C, VCC= 3.0V FORCEON = FORCEOFF = VCC= 3.0V, no load mA2.0 3.0

T_IN, FORCEON, FORCEOFF T_IN, FORCEON, FORCEOFF T_IN, FORCEON = FORCEOFF = 0V or V R_OUT, I R_OUT, I R_OUT, 0V ≤ R_OUT ≤ VCC,

FORCEON = FORCEOFF = 0V

Figure 4a

1µA supply current, Figure 4a I

OUT

CONDITIONS

= 1.0mA

OUT

= -0.4mA

OUT

Positive threshold Negative threshold -2.8

= 1.0mA, -0.3V < R_IN < 0.3V = -0.4mA, |R_IN|> 2.8V

Short-Circuit Duration, R_OUT, T_OUT to GND ....... Continuous

Continuous Power Dissipation (T

Plastic DIP (derate 11.11mW/°C above +70°C) ..........889mW

SSOP (derate 8.00mW/°C above +70°C) ..................640mW

Operating Temperature Ranges

MAX3218C_ P................................................... 0°C to +70°C

MAX3218E_ P................................................. -40°C to +85°C

Storage Temperature Range ........................... -65°C to +150°C

Lead Temperature (soldering, 10sec) ........................... +300°C

VCC- 0.25

MIN

to T

= +70°C)

, unless otherwise noted.

MAX

1.0 10

2.8

UNITSMIN TYP MAXPARAMETER

V1.8 4.25Operating Voltage Range

µA1.0 10Supply Current, AutoShutdown™

V0.33 x V V0.67 x V

µA0.001 ±1Input Leakage Current

V0.4Output Voltage Low VVCC- 0.25 VCC- 0.08Output Voltage High

µA0.05 ±10Output Leakage Current

V-0.3 0.3 V

2 _______________________________________________________________________________________

1µA Supply Current, 1.8V to 4.25V-Powered

RS-232 Transceiver with AutoShutdown™

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, VCC= 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA= T Typical values are at V

EIA/TIA-232E RECEIVER INPUTS

Input Threshold Low

Input Threshold High Input Hysteresis V

Input Resistance

EIA/TIA-232E TRANSMITTER OUTPUTS

Output Short-Circuit Current mA

= 3.0V, TA= +25°C.)

VCC= 2.0V to 4.25V VCC= 1.8V to 4.25V VCC= 1.8V to 4.25V V

-15V < R_IN < 15V kΩ357

All transmitter outputs loaded with 3kΩ to groundOutput Voltage Swing V±5 ±6 VCC= 0V, -2V < T_OUT < 2V

CONDITIONS

0.4

0.3

= 1.8V to 3.6V

to T

MIN

MAX

0.7

±24 ±100

, unless otherwise noted.

UNITSMIN TYP MAXPARAMETER

3.0

2.8

TIMING CHARACTERISTICS

(Circuit of Figure 1, VCC= 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA= T Typical values are at V

= 3.0V, TA= +25°C.)

MIN

to T

, unless otherwise noted.

MAX

MAX3218

V-25 +25Input Voltage Range V

Ω300Output Resistance

Receiver Output Enable Time Receiver Output Disable Time Transmitter Output Enable Time Transmitter Output Disable Time

Receiver Propagation Delay

Transmitter Propagation Delay

AUTOSHUTDOWN TIMING

Receiver Threshold to Transmitters Enabled

Receiver Positive or Negative Threshold to INVALID High

Receiver Positive or Negative Threshold to INVALID Low

ER DR ET

DT PHLR PLHR PHLT PLHT

INVH

INVL

CONDITIONS

2500pF || 3kΩ load each transmitter, one transmitter switching, 150pF load each receiver

150pF load 150pF load 2500pF || 3kΩ load 2500pF || 3kΩ load TA= +25°C, VCC= 3.0V, RL= 3kΩ to 7kΩ,

CL= 50pF to 2500pF, measured from +3V to -3V or -3V to +3V

Figure 4b µs250t

Figure 4b µs1t

Figure 4b µs30t

UNITSMIN TYP MAXSYMBOLPARAMETER

kbps120 235Data Rate

ns90 300t ns200 500t µs250 450t

ns500t 290 1000t 260 1000t

1.9 2.7t

1.8 2.7t

µs

V/µs3.0 30Transition Region Slew Rate

_______________________________________________________________________________________ 3

1µA Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdown™

__________________________________________Typical Operating Characteristics

(Circuit of Figure 1, VCC= 1.8V, all transmitter outputs loaded with 3kΩ, TA = +25°C, unless otherwise noted.)

140

120

MAX3218

100

SUPPLY CURRENT (mA)

SUPPLY CURRENT vs.

SUPPLY VOLTAGE

1 TRANSMITTER FULL DATA RATE 1 TRANSMITTER 1/8 DATA RATE RL = 3kΩ + 2500pF

240kbps

120kbps

20kbps

0kbps

2.4 3.0

1.8 SUPPLY VOLTAGE (V)

3.6

4.2

2V/div

MAX3218-01

TIME TO EXIT SHUTDOWN

(ONE TRANSMITTER HIGH,

ONE TRANSMITTER LOW)

TRANSMITTING SUPPLY CURRENT

vs. LOAD CAPACITANCE

100

VCC = 2.4V

90 80

235kbps 70 60

120kbps 50

SUPPLY CURRENT (mA)

20kbps

30 20

1000

LOAD CAPACITANCE (pF)

FORCEON, FORCEOFF

T_OUT

TRANSMITTER 1 OPERATING  AT SPECIFIED BIT RATE,  TRANSMITTER 2 OPERATING  AT 1/16 THAT RATE. 

3000

2000

4000

MAX3218-02

5000

1.8V

TRANSMITTER OUTPUT VOLTAGE vs. 

LOAD CAPACITANCE AT 120kbps

8 6 4 2

-2

-4

TRANSMITTER OUTPUT VOLTAGE (V)

-6

-8 1000

LOAD CAPACITANCE (pF)

2000

3000

OUT+

OUT-

4000

MAX3218-04

5000

CC =

= 3kΩ || 2500pF

100µs/div

SLEW RATE vs.

TRANSMITTER CAPACITANCE

SLEW RATE (V/µs)

DATA RATE 120kbps, TRANSMITTERS LOADED WITH 

3kΩ PLUS INDICATED CAPACITANCE 

1000

+SLEW

-SLEW

2000

3000

LOAD CAPACITANCE (pF)

4 _______________________________________________________________________________________

4000

MAX3218-05

5000

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