19-0312; 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. A guaranteed data
rate of 235kbps provides compatibility with popular software 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 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 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.
____________________________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
♦
♦
♦
♦
♦
♦
♦
__________Typical Operating Circuit
0.68µF 1N6050 15µH
+3.0V
0.33µF
3 27
1
VCC V+ LN
1N6050
2 16
LP
V-
0.33µF
26 FORCEON
+3.0V
25 FORCEOFF
5 TRAN
6
MAX3212
INVALID
13 T1IN
14 T2IN
T2OUT 18
T2
15 T3IN
T3OUT 17
T3
8 R1OUT
________________________Applications
T1OUT 19
T1
R1IN 24
R1
5k
Notebook and Palmtop Computers
9 R2OUT
Peripherals
R2IN 23
R2
5k
Instruments
10 R3OUT
Battery-Powered Equipment
R3IN 22
R3
5k
11 R4OUT
PART
TEMP. RANGE
0°C to +70°C
28 Wide SO
MAX3212CAI
0°C to +70°C
28 SSOP
MAX3212EWI
-40°C to +85°C
MAX3212EAI
-40°C to +85°C
5k
PIN-PACKAGE
MAX3212CWI
R4IN 21
R4
______________Ordering Information
12 R5OUT
R5IN 20
R5
7 R5OUTB
R5
5k
28 Wide SO
28 SSOP
+3.0V
EN
4
GND
28
AUTOSHUTDOWN OPERATION
FORCEOFF = HIGH, FORCEON = LOW
Pin Configuration appears at end of data sheet.
* ng
RS-232 Present
Yes
No
Status
On
Shut Down
________________________________________________________________ Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
1
MAX3212*
_______________General Description
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.......................................................(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
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.
ELECTRICAL CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
Operating Voltage Range
Meets or exceeds EIA/TIA-232E specifications
2.7
All R_IN unconnected, FORCEON = GND
VCC Supply Current
1
FORCEOFF = GND
FORCEON = FORCEOFF = VCC, no load
3.6
V
10
µA
µA
1
10
1.5
3.0
mA
LOGIC INPUT AND RECEIVER OUTPUTS
0.3VCC
- 0.1
Input Logic Threshold Low
T_IN, EN, FORCEON, FORCEOFF
Input Logic Threshold High
T_IN, EN, FORCEON, FORCEOFF
Input Current High
T_IN, EN, FORCEON, FORCEOFF
1
µA
Input Current Low
T_IN, EN, FORCEON, FORCEOFF
1
µA
Hysteresis
T_IN, VCC = 3.3V
Logic Output Voltage Low
IOUT = 1.0mA
Logic Output Voltage High
IOUT = -1.0mA
Logic Output Leakage Current
EN = GND, 0V < R_OUT < VCC
0.67VCC
+ 0.1
V
V
0.3
V
0.4
V
±10
µA
VCC - 0.5
V
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)
2
Positive threshold
Receiver Input Thresholds,
Transmitters Enabled
Figure 4
Receiver Input Thresholds,
Transmitters Disabled
1µA supply current, Figure 4
INVALID Output Voltage Low
IOUT = 1.0mA
INVALID Output Voltage High
IOUT = -1.0mA
Receiver Threshold to Transmitters
Enabled, tWU
Figure 4b
Receiver Positive or Negative
Threshold to Invalid High, tINVH
Receiver Positive or Negative
Threshold to Invalid Low, tINVL
Negative threshold
3.0
-3.0
-0.3
VCC - 0.6
V
0.3
V
0.4
V
V
250
µs
Figure 4
1
µs
Figure 4
30
µs
_______________________________________________________________________________________
+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
±5.5
V
V
7
kΩ
EIA/TIA-232E
EIA/TIA-232ETRANSMITTERS
TRANSMITTERS
Output Voltage Swing (VHIGH, VLOW)
All transmitters loaded with 3kΩ to GND
±5.0
Output Resistance
VCC = V- = V+ = 0V, -2V < T_OUT < 2V
300
EIA/TIA-232E Short-Circuit Current
V
Ω
28
60
mA
MOUSE DRIVEABILITY
Transmitter Output Voltage
TIN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩ to GND,
T1OUT and T2OUT loaded with 5mA
±5
V
TIMING CHARACTERISTICS
(VCC = 2.7V to 3.6V, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
RL = 3kΩ, CL = 1000pF, one transmitter
switching, 150pF load on each receiver
Data Rate
MIN
TYP
235
250
MAX
UNITS
kbps
Receiver Output Enable Time
tER
70
200
ns
Receiver Output Disable Time
tDR
420
700
ns
Transmitter Output Enable Time
tET
Transmitter Output Disable Time
tDT
Receiver Propagation Delay
tPHLR
tPLHR
Receiver Skew
Transmitter Propagation Delay
tPHLT
tPLHT
Includes power-supply start-up
150pF load
tPHL - tPLH
tPHL - tPLH
Transition-Region Slew Rate
RL = 3kΩ to 7kΩ,
measured from +3V
to -3V or -3V to +3V
µs
600
ns
630
2000
630
2000
40
2500pF 3kΩ load
Transmitter Skew
250
ns
ns
800
2000
800
2000
52
ns
ns
CL = 50pF to 2500pF
4.0
10
30
CL = 50pF to 1000pF
6
13
30
V/µs
EN High to TRAN
Reset Delay
5
µs
EN High Pulse Width
1
µs
_______________________________________________________________________________________
3
__________________________________________Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
TRANSMITTING SUPPLY CURRENT
vs. LOAD CAPACITANCE
60
50
35
30
25
TRANSMITTERS LOADED
WITH 3kΩ + 2500pF
1 TRANSMITTER (FULL DATA RATE)
2 TRANSMITTERS (DATA RATE/8)
20
15
0
50
100
150
200
50
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
55
235kbps
45
40
35
120kbps
30
30
20
3kΩ + 120kbps
10
3kΩ + 20kbps
3kΩ ONLY
0
20
20kbps
-10
15
250
1000
0
2000
3000
4000
2.0
5000
3.0
7.5
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3212-04
12
+SLEW
-SLEW
8
6
4
TRANSMITTERS LOADED
WITH 3kΩ AND SPECIFIED
CAPACITANCE AT 232kbps
0
VOUT+
5.0
TRANSMITTERS LOADED WITH 3kΩ
AND SPECIFIED CAPACITANCE
2.5
0
-2.5
VOUT-
-5.0
-7.5
0
1000
2000
3000
4000
1000
0
5000
2000
3000
4000
5000
LOAD CAPACITANCE/TRANSMITTER (pF)
LOAD CAPACITANCE/TRANSMITTER (pF)
TIME TO EXIT SHUTDOWN: ONE
TRANSMITTER HIGH, ONE TRANSMITTER LOW
FORCEON,
FORCEOFF
VOH
0V
T_OUT
2V/div
0V
VOL
RL = 3kΩ || 2500pF
100µs/div
4
3.5
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE AT 235kbps
14
10
2.5
SUPPLY VOLTAGE (V)
LOAD CAPACITANCE/TRANSMITTER (pF)
SLEW RATE
vs. LOAD CAPACITANCE
SLEW RATE (V/µs)
40
25
DATA RATE (kbps)
2
3kΩ + 235kbps
MAX3212-05
40
60
MAX3212-02
65
MAX3212-01
45
MAX3212-03
TRANSMITTING SUPPLY CURRENT
vs. DATA RATE
SUPPLY CURRENT (mA)
MAX3212
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
_______________________________________________________________________________________
4.0
+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. 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.
Complementary Output of R5OUT—always active
7
R5OUTB
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-
17, 18, 19
T3OUT, T2OUT, T1OUT
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
27
V+
28
GND
Negative Supply generated on-board
Transmitter Outputs
Drive high to overide automatic circuitry, keeping transmitters on (see Figure 3).
FORCEOFF = high.
Positive Supply generated on-board
Ground
_______________Detailed Description
The MAX3212 line driver/receiver is intended for 3Vpowered 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 RS232 levels. External components are small and inex pensive.
The transmitters and receivers are guaranteed to operate 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 incoming 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 power supply.
Use a 15µH inductor with a saturation current rating of at
least 350mA and under 1 Ω resistance. 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
_______________________________________________________________________________________
5
MAX3212
______________________________________________________________Pin Description
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.
RS-232 Drivers
All three drivers are identical and deliver EIA/TIA-232E
and EIA/TIA-562 output voltage levels when V CC is between 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 complementary (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 status. 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 shutdown. (See Figure 2.)
Enable Control
The EN input has two functions: It allows enabling/disabling 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.
Table 1. Suggested Component Suppliers
MANUFACTURER
PART NUMBER
PHONE
FAX
Diodes
Allegro
TMPD6050LT
USA (508) 853-5000
USA (508) 853-5049
Motorola
MMBD6050LT1
USA (408) 749-0510
USA (408) 991-7420
Philips
PMBD6050
USA (401) 762-3800
USA (401) 767-4493
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
Inductors
Table 2. AutoShutdown Logic
6
RS-232 SIGNAL
PRESENT AT
RECEIVER INPUT
FORCEOFF INPUT
Yes
No
FORCEON
INPUT
INVALID OUTPUT
H
X
H
Normal Operation
H
H
L
Normal Operation (Forced On)
TRANSCEIVER STATUS
No
H
L
L
Shutdown (AutoShutdown)
Yes
L
X
H
Shutdown (Forced Off)
No
L
X
L
Shutdown (Forced Off)
_______________________________________________________________________________________
+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. Interface Under Control of PMU
TO
µP
LOGIC
TRANSITION
DETECTOR
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 5kΩ resistors pull the receiver 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 transmitters 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
R5OUTB
VCC
ESD
PROTECTION
DIODE
Rx
EN = LOW
UART
Tx
GND
R5IN
R5OUT
T1IN
5k
T1OUT
SHDN = LOW
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.
Figure 2. Detection of RS-232 Activity when the UART and
Interface Are Shut Down: MAX3212 (b) vs. Previous
Transceivers (a)
_______________________________________________________________________________________
7
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.
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
Figure 3. AutoShutdown Logic
Table 2 summarizes the MAX3212 operating modes.
FORCEON and FORCEOFF override the automatic circuitry and force the transceiver into its normal operating state or into its low-power standby state. When
neither control is asserted, the IC selects between
these states automatically based on receiver input levels. 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 circuit that forces the transmitters on for 100ms after startup, 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 RS232 ports on both systems remain enabled.
8
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 RS232 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
+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. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
RECEIVER
INPUT
VOLTAGE
(V)
INVALID
REGION
VCC
INVALID
OUTPUT
(V)
0
tINVL
tINVH
tWU
V+
VCC
V-
(b)
Figure 4. AutoShutdown Trip Levels
_______________________________________________________________________________________
9
+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. 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 serial mice and met their respective current and voltage
requirements.
3
1
VCC = 2.7V
VCC = 3.3V
T1IN AND T2IN = GND
T3IN = VCC
T3OUT, T2OUT, T1OUT
ALL LOADED
SIMULTANEOUSLY
-1
-3
-5
Figure 6 shows the transmitter output voltages under
increasing load current. The MAX3212’s switching regulator ensures the transmitters will supply at least ±5V
during worst-case load conditions.
T3OUT
-7
0
1
2
3
4
5
6
7
8
9
LOAD CURRENT PER TRANSMITTER (mA)
Figure 6. Mouse Emulation Circuit Current
_____+3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
PART
POWERSUPPLY
VOLTAGE
(V)
No. OF
TRANSMITTERS/
RECEIVERS
No. OF
RECEIVERS
ACTIVE IN
SHUTDOWN
GUARANTEED
DATA
RATE
(kbps)
EIA/TIA232
OR 562
MAX212
3.0 to 3.6
3/5
5
120
232
Drives mice
MAX218
1.8 to 4.25
2/2
2
120
232
Operates directly from batteries
without a voltage regulator
MAX562
MAX563
2.7 to 5.25
3.0 to 3.6
3/5
2/2
5
2
230
230
562
562
MAX3212
2.7 to 3.6
3/5
5
235
232
MAX3222
3.0 to 5.5
2/2
2
120
232
0.1µF capacitors
MAX3223
MAX3232
3.0 to 5.5
3.0 to 5.5
2/2
2/2
2
N/A
120
120
232
232
0.1µF capacitors, AutoShutdown
0.1µF capacitors
MAX3241
3.0 to 5.5
3/5
5
120
232
0.1µF capacitors, 2 complementary receivers, drives mice
MAX3243
3.0 to 5.5
3/5
1
120
232
0.1µF capacitors, AutoShutdown,
complementary receiver,
drives mice
10
FEATURES
Wide supply range
0.1µF capacitors
AutoShutdown, complementary
receiver, drives mice, transient
detection
______________________________________________________________________________________
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
MAX3212
__________________Pin Configuration
TOP VIEW
LN 1
28 GND
LP 2
27 V+
VCC 3
26 FORCEON
EN 4
25 FORCEOFF
TRAN 5
INVALID 6
MAX3212
24 R1IN
23 R2IN
R5OUTB 7
22 R3IN
R1OUT 8
21 R4IN
R2OUT 9
20 R5IN
R3OUT 10
19 T1OUT
R4OUT 11
18 T2OUT
R5OUT 12
17 T3OUT
T1IN 13
16 V-
T2IN 14
15 T3IN
SO/SSOP
TRANSISTOR COUNT: 1435
______________________________________________________________________________________
11
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
0.63
0˚
8˚
8˚
0˚
DIM PINS
e
SSOP
SHRINK
SMALL OUTLINE
PACKAGE
A
B
A1
D
D
D
D
D
D
21-0056A
DIM
D
0°- 8°
A
e
B
0.101mm
0.005in.
A1
E
C
L
W PACKAGE
SMALL
OUTLINE
H
14
16
20
24
28
INCHES
MILLIMETERS
MAX
MIN MAX MIN
6.33
0.239 0.249 6.07
6.33
0.239 0.249 6.07
7.33
0.278 0.289 7.07
8.33
0.317 0.328 8.07
0.397 0.407 10.07 10.33
A
A1
B
C
E
e
H
L
INCHES
MAX
MIN
0.104
0.093
0.012
0.004
0.019
0.014
0.013
0.009
0.299
0.291
0.050
0.419
0.394
0.050
0.016
DIM PINS
D
D
D
D
D
16
18
20
24
28
INCHES
MIN MAX
0.398 0.413
0.447 0.463
0.496 0.512
0.598 0.614
0.697 0.713
MILLIMETERS
MIN
MAX
2.35
2.65
0.10
0.30
0.35
0.49
0.23
0.32
7.40
7.60
1.27
10.00
10.65
0.40
1.27
MILLIMETERS
MIN
MAX
10.10 10.50
11.35 11.75
12.60 13.00
15.20 15.60
17.70 18.10
21-0042A
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.
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