_______________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
1
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
R1 R1IN
R2 R2IN
R3 R3IN
R4 R4IN
R5 R5IN
R5
EN GND
T3
T2
T1
T3OUT
T2OUT
T1OUT
R1OUT
R2OUT
R3OUT
R4OUT
R5OUT
R5OUTB
T3IN
T2IN
T1IN
VCC
26
25
5
6
+3.0V
0.33µF
0.68µF 1N6050 1N605015µH
0.33µF
V+ LN LP V-
FORCEON
TRAN
INVALID
FORCEOFF
5k
5k
5k
5k
5k
MAX3212
327 1 216
13
14
15
8
9
10
11
12
7
19
18
17
24
23
22
21
20
284
+3.0V
+3.0V
AUTOSHUTDOWN OPERATION
FORCEOFF = HIGH, FORCEON = LOW
RS-232 Present
Yes
No
Status
On
Shut Down
19-0312; Rev 0; 9/94
µA
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA= TMIN to TMAX, unless otherwise noted.)
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.
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.......................................................(V- - 1.0V) to (V+ + 0.3V)
Input Voltages
T_IN, EN, FORCEON, FORCEOFF .....................-0.3V to +7.0V
R_IN ..................................................................................±25V
Output Voltages
T_OUT...............................................................................±15V
R_OUT, R5OUTB, INVALID, TRAN............-0.3V to (V+ + 0.3V)
Short-Circuit Duration, T_OUT....................................Continuous
Continuous Power Dissipation (TA= +70°C)
Wide SO (derate 11.76mW/°C above +70°C)...............941mW
SSOP (derate 8.00mW/°C above +70°C) .....................640mW
Operating Temperature Ranges
MAX3212C_ I .......................................................0°C to +70°C
MAX3212E_ I ....................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
PARAMETER
Logic Output Voltage Low
MIN TYP MAX
0.4
UNITS
Input Logic Threshold Low
V
0.3VCC
- 0.1
Logic Output Voltage High
V
VCC - 0.5 V
Logic Output Leakage Current
Input Logic Threshold High 0.67VCC
+ 0.1 V
Input Current High 1 µA
±10 µA
Input Current Low 1 µA
Hysteresis 0.3 V
Operating Voltage Range 2.7 3.6 V
CONDITIONS
IOUT = 1.0mA
T_IN, EN, FORCEON, FORCEOFF
IOUT = -1.0mA
T_IN, EN, FORCEON, FORCEOFF
T_IN, EN, FORCEON, FORCEOFF
EN = GND, 0V < R_OUT < VCC
T_IN, EN, FORCEON, FORCEOFF
T_IN, VCC = 3.3V
Meets or exceeds EIA/TIA-232E specifications
3.0
Receiver Input Thresholds,
Transmitters Enabled
Receiver Input Thresholds,
Transmitters Disabled -0.3 0.3 V1µA supply current, Figure 4
-3.0 VFigure 4
INVALID Output Voltage Low
INVALID Output Voltage High VCC - 0.6 VIOUT = -1.0mA
Receiver Threshold to Transmitters
Enabled, tWU 250 µsFigure 4b
0.4 VIOUT = 1.0mA
Positive threshold
Negative threshold
Receiver Positive or Negative
Threshold to Invalid High, tINVH 1 µsFigure 4
110All R_IN unconnected, FORCEON = GND
VCC Supply Current
1.5 3.0 mAFORCEON = FORCEOFF = VCC, no load
110
µA
FORCEOFF = GND
Receiver Positive or Negative
Threshold to Invalid Low, tINVL 30 µsFigure 4
DC CHARACTERISTICS
LOGIC INPUT AND RECEIVER OUTPUTS
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 2.7V to 3.6V, TA= TMIN to TMAX, unless otherwise noted.)
TIMING CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA= TMIN to TMAX, unless otherwise noted.)
PARAMETER
Receiver Propagation Delay 630 2000
MIN TYP MAX
ns150pF load
UNITS
800 2000
Data Rate
Transmitter Propagation Delay 800 2000 ns
Transmitter Output Disable Time
2500pF 3kΩload
600 ns
235 250 kbps
630 2000
Transmitter Output Enable Time
RL= 3kΩ, CL= 1000pF, one transmitter
switching, 150pF load on each receiver
250 µs
SYMBOL
tPLHR
tPHLT
tPLHT
tDT
tPHLR
tET
tER
tDR
Receiver Output Enable Time 70 200 ns
Receiver Output Disable Time 420 700 ns
CONDITIONS
Includes power-supply start-up
V/µsTransition-Region Slew Rate
5 µs
EN High to TRAN
Reset Delay
1 µsEN High Pulse Width
RL= 3kΩto 7kΩ,
measured from +3V
to -3V or -3V to +3V
CL= 50pF to 2500pF
CL= 50pF to 1000pF 61330
4.0 10 30
Receiver Skew ns
tPHL - tPLH 40
52Transmitter Skew ns
tPHL - tPLH
EIA/TIA-232E TRANSMITTERS
Input Voltage Threshold High 3.0 V
Input Hysteresis 0.7 V
Output Voltage Swing (VHIGH, VLOW) ±5.0 ±5.5 V
Output Resistance 300 Ω
EIA/TIA-232E Short-Circuit Current 28 60 mA
All transmitters loaded with 3kΩto GND
VCC = V- = V+ = 0V, -2V < T_OUT < 2V
PARAMETER MIN TYP MAX UNITS
Input Voltage Threshold Low 0.4 V
Input Resistance 357kΩ
CONDITIONS
-15V < VIN < 15V
Input Voltage Operating Range -25 +25 V
TIN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩto GND,
T1OUT and T2OUT loaded with 5mA
Transmitter Output Voltage ±5 V
EIA/TIA-232E RECEIVERS
EIA/TIA-232E TRANSMITTERS
MOUSE DRIVEABILITY
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
4 _______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
15 0
TRANSMITTING SUPPLY CURRENT
vs. DATA RATE
MAX3212-01
DATA RATE (kbps)
SUPPLY CURRENT (mA)
20
25
30
35
40
45
50 100 150 200 250
TRANSMITTERS LOADED
WITH 3kΩ + 2500pF
1 TRANSMITTER (FULL DATA RATE)
2 TRANSMITTERS (DATA RATE/8) 15
20
0
TRANSMITTING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3212-02
LOAD CAPACITANCE/TRANSMITTER (pF)
SUPPLY CURRENT (mA)
25
30
35
40
45
50
55
60
65
1000 2000 3000 4000 5000
235kbps
120kbps
20kbps -10
0
2.0
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX3212-03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
10
20
30
40
50
60
2.5 3.0 3.5 4.0
3kΩ + 235kbps
3kΩ + 120kbps
3kΩ + 20kbps
3kΩ ONLY
0
2
0
SLEW RATE
vs. LOAD CAPACITANCE
MAX3212-04
LOAD CAPACITANCE/TRANSMITTER (pF)
SLEW RATE (V/µs)
4
6
8
10
12
14
1000 2000 3000 4000 5000
+SLEW
-SLEW
TRANSMITTERS LOADED
WITH 3kΩ AND SPECIFIED
CAPACITANCE AT 232kbps -7.5
-5.0
0
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE AT 235kbps
MAX3212-05
LOAD CAPACITANCE/TRANSMITTER (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
-2.5
0
2.5
5.0
7.5
1000 2000 3000 4000 5000
VOUT+
VOUT-
TRANSMITTERS LOADED WITH 3kΩ
AND SPECIFIED CAPACITANCE
TIME TO EXIT SHUTDOWN: ONE
TRANSMITTER HIGH, ONE TRANSMITTER LOW
0V
0V
2V/div
FORCEON,
FORCEOFF
VOH
T_OUT
VOL
RL = 3kΩ || 2500pF
100µs/div
_______________Detailed Description
The MAX3212 line driver/receiver is intended for 3V-
powered EIA/TIA-232E and V.28/V.24 communications
interfaces where 3 drivers and 5 receivers are required.
The operating voltage range extends from 3.6V down to
2.7V while still maintaining true RS-232 and EIA/TIA-562
transmitter output voltage levels.
The circuit comprises three sections: power supply,
transmitters, and receivers. The power-supply section
converts the supplied 3V to about ±6.5V, to provide
the voltages necessary for the drivers to meet true RS-
232 levels. External components are small and inex -
pensive.
The transmitters and receivers are guaranteed to oper-
ate at data rates of 235kbps.
The MAX3212 is equipped with Maxim’s new propri -
etary AutoShutdown circuitry. This achieves a supply
current of 1 µA by shutting down the device when the
RS-232 cable is disconnected or when the connected
peripheral transmitters are turned off. While shut down,
all receivers can remain active or can be disabled
under logic control. A complementary receiver remains
active in all cases, enabling a system incorporating the
MAX3212 to remain shut down and still monitor incom-
ing RS-232 activity.
Three-state drivers on all receiver outputs are provided
so that multiple receivers, generally of different inter -
face standards, can be wire-ORed at the UART.
Switch-Mode Power Supply
The switch-mode power supply uses a single inductor
with two inexpensive diodes and two capacitors to
generate ±6.5V from the 2.7V to 3.6V input. The
Typical
Operating Circuit
shows the complete circuit for the pow-
er supply.
Use a 15µH inductor with a saturation current rating of at
least 350mA and under 1Ωresistance. Use 1N6050
diodes or equivalent. Surface-mount equivalents for the
1N6050 include the Motorola MMBD6050LT1, P hilips
PMBD6050, and Allegro (formerly Sprague) TMPD6050LT.
For C1 and C2, use ceramic capacitors with values no
less than indicated in the
Typical Operating Circuit
.
These capacitors determine the ripple on V+ and V-, but
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
_______________________________________________________________________________________ 5
______________________________________________________________Pin Description
PIN NAME FUNCTION
1 LN Inductor/Diode Connection Point
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. TRAN latches high when a transition occurs on any receiver
input while EN is low. Reset by cycling the EN pin high then low.
6 INVALID Output of Invalid Signal Detector. Low if invalid RS-232 levels are present on all
receiver inputs, otherwise high.
7 R5OUTB Complementary Output of R5OUT—always active
8–12 R1OUT–R5OUT Receiver Outputs. Swing from GND to VCC. High-impedance when EN is low.
13, 14, 15 T1IN, T2IN, T3IN Transmitter Inputs
16 V- Negative Supply generated on-board
17, 18, 19 T3OUT, T2OUT, T1OUT Transmitter Outputs
20–24 R5IN–R1IN Receiver Inputs
25 FORCEOFF Drive low to shut down transmitters and on-board power supply, overriding all automatic
circuitry and FORCEON (see Figure 3).
26 FORCEON Drive high to overide automatic circuitry, keeping transmitters on (see Figure 3).
FORCEOFF = high.
27 V+ Positive Supply generated on-board
28 GND Ground
MAX3212
not the absolute voltages. Increasing the size of C1 and
C2 increases the time V+ and V- take to reach their final
value. Bypass VCC to GND with at least 0.33 µF close to
the MAX3212. Increase this to 4.7µF if there are no other
VCC supply bypass components less than 6 inches
(15cm) away from the MAX3212.
Component suppliers are listed in Table 1.
RS-232 Drivers
All three drivers are identical and deliver EIA/TIA-232E
and EIA/TIA-562 output voltage levels when V CC is be-
tween 2.7V and 3.6V. When FORCEOFF is driven low or
when the AutoShutdown circuitry senses invalid voltage
levels at all receiver inputs, the drivers are disabled
and the outputs are forced into a high-impedance
state.
RS-232 Receivers
The MAX3212 receivers convert RS-232 signals to
CMOS-logic output levels. All receivers have one in -
verting three-state output. Receiver 5 also has a com-
plementary (noninverting) output. In shutdown, all five
inverting receivers can be either active or inactive
under logic control.
The complementary output (R5OUTB) is always active,
regardless of the state of EN or the part’s shutdown sta-
tus. R5OUTB can monitor RS-232 activity while the
other receivers are high impedance. This allows Ring
Indicator to be monitored without forward biasing other
devices connected to the receiver outputs. This is ideal
for systems where the UART’s V CC is set to 0V in shut-
down. (See Figure 2.)
Enable Control
The EN input has two functions: It allows enabling/dis-
abling of the receivers, and it is used to reset the transi-
tion detector.
Driving EN low places five inverting receiver outputs
(R_OUT) into a high-impedance state. R5OUTB is
always active, regardless of the state of EN or the part’s
shutdown status (Table 2). EN has no effect on T_OUT.
EN also resets the transition detector. Drive EN high and
then low to reset the TRAN output low. TRAN goes high
when a transition occurs on any receiver input.
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
6 _______________________________________________________________________________________
Table 1. Suggested Component Suppliers
Table 2. AutoShutdown Logic
MANUFACTURER PART NUMBER PHONE FAX
Motorola MMBD6050LT1 USA (408) 749-0510 USA (408) 991-7420
Murata-Erie LQH4N150K-TA USA (404) 436-1300
Japan (075) 951-9111
USA (404) 684-1541
Japan (075) 955-6526
Sumida CD43150 USA (708) 956-0666
Japan (03) 3607-5111
USA (708) 956-0702
Japan (03) 3607-5428
TDK NLC453232T-150K USA (708) 803-6100
Japan (03) 3278-5111
USA (708) 803-6296
Japan (03) 3278-5358
Allegro TMPD6050LT USA (508) 853-5000 USA (508) 853-5049
Philips PMBD6050 USA (401) 762-3800 USA (401) 767-4493
RS-232 SIGNAL
PRESENT AT
RECEIVER INPUT
FORCEOFF INPUT FORCEON
INPUT INVALID OUTPUT TRANSCEIVER STATUS
Yes H X H Normal Operation
No H H L Normal Operation (Forced On)
No H L L Shutdown (AutoShutdown)
Yes L X H Shutdown (Forced Off)
No L X L Shutdown (Forced Off)
Diodes
Inductors
AutoShutdown
A 1µA supply current is achieved with Maxim’s new
AutoShutdown feature, which operates when
FORCEON is low and FORCEOFF is high. When the
MAX3212 senses no valid signal level on any receiver
input for typically 30µs, the on-board power supply and
drivers shut down. Internal 5kΩresistors pull the receiv-
er inputs to ground, disabling the transmitters and
reducing supply current to 1 µA when the device is in
AutoShutdown mode. This occurs if the RS-232 cable is
disconnected or if the connected peripheral transmit-
ters are turned off. The system 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 BIOS or operating system. When using the
AutoShutdown feature, INVALID is high when the
device is on and low when the device is shut down. The
INVALID output indicates the condition of the receiver
inputs; INVALID can be used in any mode.
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
_______________________________________________________________________________________ 7
MAX3212
T1OUT
R5OUTB
Tx
5k
UART
VCC
T1IN
LOGIC
TRANSITION
DETECTOR
R5IN
R5OUT
EN = LOW
SHDN = LOW
VCC
TO
µP
Rx
PREVIOUS
RS-232
Tx
UART
SHDN = LOW
VCC
VCC
GND
Rx
5k
a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM
ACTIVE RECEIVER OUTPUT IN SHUTDOWN.
b) NEW MAX3212: EN SHUTS DOWN RECEIVER OUTPUTS (EXCEPT FOR R5OUTB)
SO NO CURRENT FLOWS TO UART IN SHUTDOWN. R5OUTB INDICATES RECEIVER
ACTIVITY DURING SHUTDOWN WITH EN HIGH.
GND
ESD
PROTECTION
DIODE
ESD
PROTECTION
DIODE
POWER
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER
CPU
I/O
CHIP
WITH
UART
MAX3212
RS-232
FORCEOFF
FORCEON
INVALID
Figure 1. Interface Under Control of PMU
Figure 2. Detection of RS-232 Activity when the UART and
Interface Are Shut Down: MAX3212 (b) vs. Previous
Transceivers (a)
MAX3212
Table 2 summarizes the MAX3212 operating modes.
FORCEON and FORCEOFF override the automatic cir-
cuitry and force the transceiver into its normal operat-
ing state or into its low-power standby state. When
neither control is asserted, the IC selects between
these states automatically based on receiver input lev-
els. Figure 4 depicts valid and invalid RS-232 receiver
levels. The MAX3212 shuts down after sensing invalid
RS-232 levels for greater than 30 µs, ensuring the
AutoShutdown mode is not enabled for slow-moving
signals (1V/µs).
A mouse or another system with AutoShutdown may
need a period of time to wake up. Figure 5 shows a cir-
cuit that forces the transmitters on for 100ms after start-
up, allowing enough time for the other system to realize
that the MAX3212 system is awake. If the other system
outputs valid RS-232 signals within that time, the RS-
232 ports on both systems remain enabled.
Transition Detector
The MAX3212 also has an on-board transition detector
that monitors activity on the receiver inputs. In systems
with a sleep mode, the transition detector output (TRAN)
can be used to wake up the system when activity at the
receiver inputs is detected. Before putting the system to
sleep, set TRAN low by cycling EN high and then low.
TRAN remains low as long as no activity is detected on
the receiver inputs. When any receiver is toggled, TRAN
latches high. Connect TRAN to a microprocessor inter -
rupt, or if the system wakes up periodically TRAN can
be polled. Transition detection is useful when valid RS-
232 levels are present at the receiver inputs but no data
is being sent. For example, if a printer is attached to the
serial port but is not in use, the microprocessor senses
this and forces the MAX3212 off.
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
8 _______________________________________________________________________________________
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.
FORCEOFF
0
0
0
0
1
1
1
1
FORCEON
0
0
1
1
0
0
1
1
INVALID
0
1
0
1
0
1
0
1
POWER DOWN
0
0
0
0
0
1
1
1
POWER DOWN
FORCEOFF
FORCEON
INVALID
+
-
+
-
RxRIN_
EN
ROUT_
30µs
DELAY
•
•
•
•
•
•
+0.3V to +3.0V
-0.3V to -3.0V
Figure 3. AutoShutdown Logic
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
_______________________________________________________________________________________ 9
FORCEON
MASTER SHDN LINE
0.1µF 1M
FORCEOFF
MAX3212
POWER
MANAGEMENT
UNIT
V-
VCC
V+
0
VCC
tINVL tWU
INVALID
REGION
RECEIVER
INPUT
VOLTAGE
(V)
INVALID
OUTPUT
(V)
tINVH
Figure 5. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
Figure 4. AutoShutdown Trip Levels
TRANSMITTERS ENABLED, INVALID HIGH
AUTOSHUTDOWN, TRANSMITTERS DISABLED,
1µA SUPPLY CURRENT, INVALID LOW
TRANSMITTERS ENABLED, INVALID HIGH
-3.0V
-0.3V
+3.0V
+0.3V
0V
INDETERMINATE
INDETERMINATE
(b)
(a)
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
10 ______________________________________________________________________________________
_____+3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
-7
-5
0
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CURRENT PER TRANSMITTER
MAX3212-06
LOAD CURRENT PER TRANSMITTER (mA)
TRANSMITTER OUTPUT VOLTAGE (V)
-3
-1
3
1
5
7
12345
V
CC = 3.3V
VCC = 2.7V
T1IN AND T2IN = GND
T3IN = VCC
T3OUT, T2OUT, T1OUT
ALL LOADED
SIMULTANEOUSLY
6789
T3OUT
T1OUT AND T2OUT
Figure 6. Mouse Emulation Circuit Current
0.1µF capacitors, AutoShutdown,
complementary receiver,
drives mice
23212013/53.0 to 5.5MAX3243
0.1µF capacitors232120N/A2/23.0 to 5.5MAX3232
0.1µF capacitors, AutoShutdown23212022/23.0 to 5.5MAX3223
0.1µF capacitors23212022/23.0 to 5.5MAX3222
232
562
232
562
232
EIA/TIA-
232
OR 562
2.7 to 3.6
AutoShutdown, complementary
receiver, drives mice, transient
detection
23553/5MAX3212
0.1µF capacitors23022/23.0 to 3.6MAX563
Operates directly from batteries
without a voltage regulator
12022/21.8 to 4.25MAX218
No. OF
RECEIVERS
ACTIVE IN
SHUTDOWN
POWER-
SUPPLY
VOLTAGE
(V)
Wide supply range23053/52.7 to 5.25MAX562
Drives mice12053/53.0 to 3.6MAX212
FEATURES
GUAR-
ANTEED
DATA
RATE
(kbps)
No. OF
TRANSMITTERS/
RECEIVERS
PART
Driving the MAX3212 from 5V Logic
The MAX3212 can directly interface with various 5V
logic families, including ACT and HCT CMOS.
Mouse Driveability
The MAX3212 has been specifically designed to power
serial mice while operating from low-voltage power sup-
plies. It has been tested with samples of ten major
mouse models from six manufacturers, including the
leading three, Logitech (5 models), Mouse Systems,
and Microsoft. The MAX3212 successfully drove all ser-
ial mice and met their respective current and voltage
requirements.
Figure 6 shows the transmitter output voltages under
increasing load current. The MAX3212’s switching reg-
ulator ensures the transmitters will supply at least ±5V
during worst-case load conditions.
0.1µF capacitors, 2 complemen-
tary receivers, drives mice
23212053/53.0 to 5.5MAX3241
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
______________________________________________________________________________________ 11
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
GND
V+
FORCEON
FORCEOFF
R1IN
R2IN
R3IN
R4IN
R5IN
T1OUT
T2OUT
T3OUT
V-
T3IN
LN
LP
VCC
EN
TRAN
INVALID
R5OUTB
R1OUT
R2OUT
R3OUT
R4OUT
R5OUT
T1IN
T2IN
SO/SSOP
TOP VIEW
MAX3212
__________________Pin Configuration
TRANSISTOR COUNT: 1435
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.
12
__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1994 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
________________________________________________________Package Information
L
DIM
A
A1
B
C
D
E
e
H
L
α
DIM
D
D
D
D
D
MIN
0.068
0.002
0.010
0.004
0.205
0.301
0.025
0˚
MIN
0.239
0.239
0.278
0.317
0.397
MAX
0.078
0.008
0.015
0.008
0.209
0.311
0.037
8˚
MAX
0.249
0.249
0.289
0.328
0.407
MIN
1.73
0.05
0.25
0.09
5.20
7.65
0.63
0˚
MIN
6.07
6.07
7.07
8.07
10.07
MAX
1.99
0.21
0.38
0.20
5.38
7.90
0.95
8˚
PINS
14
16
20
24
28
MAX
6.33
6.33
7.33
8.33
10.33
INCHES
INCHES
MILLIMETERS
MILLIMETERS
α
SSOP
SHRINK
SMALL OUTLINE
PACKAGE
HE
D
A
A1
C
B
0.65 BSC0.0256 BSC
21-0056A
e
SEE VARIATIONS
DIM
A
A1
B
C
E
e
H
L
MIN
0.093
0.004
0.014
0.009
0.291
0.394
0.016
MAX
0.104
0.012
0.019
0.013
0.299
0.419
0.050
MIN
2.35
0.10
0.35
0.23
7.40
10.00
0.40
MAX
2.65
0.30
0.49
0.32
7.60
10.65
1.27
INCHES MILLIMETERS
21-0042A
W PACKAGE
SMALL
OUTLINE
DIM
D
D
D
D
D
MIN
0.398
0.447
0.496
0.598
0.697
MAX
0.413
0.463
0.512
0.614
0.713
MIN
10.10
11.35
12.60
15.20
17.70
MAX
10.50
11.75
13.00
15.60
18.10
INCHES MILLIMETERS
PINS
16
18
20
24
28
1.27
0.050
L
HE
D
e
A
A1 C
0°- 8°
0.101mm
0.005in.
B
