_______________General Description
The MAX3221/MAX3223/MAX3243 achieve 1A supply
current with Maxim's revolutionary AutoShutdownTM fea-
ture. When the MAX3221/MAX3223/MAX3243 do not
sense a valid signal level on their receiver inputs, the
on-board 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 BIOS or
operating system.
The MAX3221/MAX3223/MAX3243 transceivers are 3V-
powered EIA/TIA-232 and V.28/V.24 communications
interfaces intended for notebook computer applica-
tions. A proprietary, high-efficiency, 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 120kbps pro-
vides compatibility with popular software for communi-
cating with personal computers.
The MAX3221/MAX3223/MAX3243 require only 0.1F
capacitors in 3.3V operation, and can operate from input
voltages ranging from +3.0V to +5.5V. They are ideal for
3.3V-only systems, mixed 3.3V and 5.0V systems, or
5.0V-only systems that require true RS-232 performance.
The MAX3221 is a 1-driver/1-receiver 16-pin SSOP ver-
sion of the 20-pin MAX3223 (2-driver/2-receiver). The
MAX3243 3-driver/5-receiver, complete serial port is
ideal for notebook or subnotebook computers. The
MAX3243 includes one complementary always-active
receiver. This receiver can monitor an external device
(such as a modem) in shutdown, without forward bias-
ing the protection diodes in a UART that may have V
CC
completely removed.
____________________________Features
o 1A Supply Current Achieved with AutoShutdown
o Small 0.1F Capacitors
o True RS-232 Operation from V
CC
= +3.0V to +5.5V
o Meets EIA/TIA-562 Specifications Down to 2.7V
o Guaranteed 120kbps Data Rate
o 6V/s Min Guaranteed Slew Rate
o Smallest Single-Supply RS-232 Transceiver
(MAX3221)
o Guaranteed Mouse Driveability (MAX3243)
o Small TSSOP Package (MAX3223/MAX3243)
________________________Applications
Notebook, Subnotebook, and Palmtop Computers
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers
MAX3221/MAX3223/MAX3243*
1A Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
________________________________________________________________ Maxim Integrated Products
1
19-0306; Rev 6; 3/99
PART
MAX3221CAE
MAX3221EUE
-40C to +85C
0C to +70C
TEMP. RANGE
PIN-PACKAGE
16 SSOP
16 TSSOP
* Covered by U.S. Patent numbers 4,636,930; 4,679,134; 4,777,577; 4,797,899; 4,809,152; 4,897,774; 4,999,761; and other patents pending.
Future product--contact factory for availability.
AutoShutdown is a trademark of Maxim Integrated Products.
Pin Configurations appear at end of data sheet.
Typical Operating Circuits appear at end of data sheet.
MAX3223EPP
-40C to +85C
20 Plastic DIP
MAX3223EAP
-40C to +85C
20 SSOP
MAX3243CWI
0C to +70C
28 Wide SO
MAX3243CAI
0C to +70C
28 SSOP
MAX3243EWI
-40C to +85C
28 Wide SO
MAX3243EAI
-40C to +85C
28 SSOP
MAX3223CPP
MAX3223CAP
0C to +70C
0C to +70C
20 Plastic DIP
20 SSOP
______________Ordering Information
_____________________Selector Guide
MAX3221
MAX3223
MAX3243
1
2
3
1
2
3.0 to 5.5
3.0 to 5.5
3.0 to 5.5
5
Yes
Yes
Yes
PART
Tx
Rx
V
CC
RANGE (V)
AutoShutdown
MAX3221CUE
0C to +70C
16 TSSOP
MAX3221EAE
-40C to +85C
16 SSOP
MAX3223CUP
0C to +70C
20 TSSOP
MAX3223EUP
-40C to +85C
20 TSSOP
MAX3243CUI
0C to +70C
28 TSSOP
MAX3243EUI
-40C to +85C
28 TSSOP
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX3221/MAX3223/MAX3243
1A Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= +3.0V to +5.5V, C1C4 = 0.1F (Note 2), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25C.)
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.
V
CC
...........................................................................-0.3V to +6V
V+ (Note 1) ...............................................................-0.3V to +7V
V- (Note 1) ...............................................................+0.3V to -7V
V+ +
|
V-
|
(Note 1).................................................................+13V
Input Voltages
T_IN, FORCEOFF, FORCEON, EN (MAX3223) ......-0.3V to +6V
R_IN ...................................................................................25V
Output Voltages
T_OUT.............................................................................13.2V
R_OUT, INVALID ......................................-0.3V to (V
CC
+ 0.3V)
Short-Circuit Duration
T_OUT ......................................................................Continuous
Continuous Power Dissipation (T
A
= +70C)
16-Pin SSOP (derate 7.14mW/C above +70C) ...........571mW
16-Pin TSSOP (derate 6.70mW/C above +70C) .........533mW
20-Pin Plastic DIP (derate 11.11mW/C above +70C)....889mW
20-Pin SSOP (derate 8.00mW/C above +70C) ...........640mW
20-Pin TSSOP DIP (derate 7.00mW/C above +70C).....559mW
28-Pin Wide SO (derate 12.50mW/C above +70C) ............1W
28-Pin SSOP (derate 9.52mW/C above +70C) ...........762mW
28-Pin TSSOP (derate 8.70mW/C above +70C) .........696mW
Operating Temperature Ranges
MAX32_ _C_ _.......................................................0C to +70C
MAX32_ _E_ _ ....................................................-40C to +85C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10sec) .............................+300C
Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
I
OUT
= 1.6mA
Receivers disabled
T_IN, EN, FORCEON, FORCEOFF
T_IN, EN, FORCEON, FORCEOFF
T_IN, FORCEON, FORCEOFF, EN (MAX3223)
I
OUT
= -1.0mA
CONDITIONS
V
V
CC
- 0.6
V
CC
- 0.1
Output Voltage High
V
0.4
Output Voltage Low
A
0.05
10
Output Leakage Current
A
0.01
1.0
Input Leakage Current
V
2.4
Input Logic Threshold High
A
1.0
10
V
0.8
Input Logic Threshold Low
UNITS
MIN
TYP
MAX
PARAMETER
V
CC
= 3.3V
V
CC
= 5.0V
2.0
Supply Current, AutoShutdown
Supply Current, Shutdown
A
1.0
10
Supply Current,
AutoShutdown Disabled
V
CC
= 3.3V
or 5.0V,
T
A
= +25C
mA
0.3
1.0
2.7
Receiver Positive or Negative
Threshold to INVALID High (t
INVH
)
Figure 5
s
1
Receiver Threshold to
Transmitters Enabled (t
WU
)
Figure 5
s
250
Receiver Positive or Negative
Threshold to INVALID Low (t
INVL
)
Figure 5
s
30
Receiver Input Thresholds to
Transmitters Enabled
Figure 5
V
-2.7
INVALID Output Voltage Low
I
OUT
= 1.6mA
V
0.4
Receiver Input Thresholds to
Transmitters Disabled
1A supply current, Figure 5
V
-0.3
0.3
Positive threshold
Negative threshold
INVALID Output Voltage High
I
OUT
= -1.0mA
V
V
CC
- 0.6
DC CHARACTERISTICS
LOGIC INPUTS AND RECEIVER OUTPUTS
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = V
CC
)
All R_IN open, FORCEON = GND,
FORCEOFF = V
CC
FORCEOFF = GND
FORCEON = FORCEOFF = V
CC
,
no load
MAX3221/MAX3223/MAX3243
1A Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, C1C4 = 0.1F (Note 2), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25C.)
Note 2: C1C4 = 0.1F, tested at 3.3V 10%. C1 = 0.047F, C2C4 = 0.33F, tested at 5.0V 10%.
200
Normal operation
200
Receiver Output Enable Time
Normal operation
ns
t
PLH
Receiver input to receiver output,
C
L
= 150pF
4
8.0
30
Transition-Region Slew Rate
V/s
V
CC
= 3.3V,
R
L
= 3k
to 7k,
T
A
= +25C,
measured from +3V to
-3V or -3V to +3V
Transmitter Skew
200
ns
t
PHL
- t
PLH
PARAMETER
MIN
TYP
MAX
UNITS
25
Output Short-Circuit Current
35
60
mA
Output Resistance
300
10M
Output Leakage Current
A
Input Threshold Low
0.6
1.2
V
5.0
5.4
Output Voltage Swing
V
Maximum Data Rate
120
235
kbps
Receiver Propagation Delay
0.3
s
CONDITIONS
V
CC
= V+ = V- = 0V, transmitter output = 2V
V
OUT
= 12V, V
CC
= 0V or 3.0V to 5.5V,
transmitters disabled
R
L
= 3k
, C
L
= 1000pF, one transmitter switching
All transmitter outputs loaded with 3k
to ground
ns
Receiver Output Disable Time
t
PHL
0.3
Input Voltage Range
-25
25
V
Input Hysteresis
0.3
V
Input Threshold High
V
Input Resistance
3
5
7
k
T
A
= +25C
0.8
1.5
1.8
2.4
1.5
2.4
T
A
= +25C
T
A
= +25C
V
CC
= 3.3V
V
CC
= 3.3V
V
CC
= 5.0V
V
CC
= 5.0V
C
L
= 200pF to 2500pF
C
L
= 200pF to 1000pF
6
30
5
Transmitter Output Voltage
V
T1IN = T2IN = GND, T3IN = V
CC
,
T3OUT loaded with 3k
to GND, T1OUT and
T2OUT loaded with 2.5mA each
MAX3221/MAX3223
MAX3243
200
1000
Receiver Skew
100
ns
t
PHL
- t
PLH
MAX3221/MAX3223
MAX3243
100
500
RECEIVER INPUTS
TIMING CHARACTERISTICS
TRANSMITTER OUTPUTS
MOUSE DRIVEABILITY (MAX3243)
MAX3221/MAX3223/MAX3243
1A Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
4
_______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(V
CC
= +3.3V, 235kbps data rate, 0.1F capacitors, all transmitters loaded with 3k
, T
A
= +25C, unless otherwise noted.)
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
0
MAX3221/MAX3223
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3221/3223-01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
2000
3000
1000
4000
5000
V
OUT+
V
OUT-
0
2
4
6
8
10
12
14
16
18
20
22
150 500
MAX3221/MAX3223
SLEW RATE
vs. LOAD CAPACITANCE
MAX3221/3223-02
LOAD CAPACITANCE (pF)
SLEW RATE (V/
s)
2000
3000
1000
4000
5000
FOR DATA RATES UP TO 235kbps
+SLEW
-SLEW
5
10
15
20
25
30
35
40
0
5
10
15
20
25
30
35
0
MAX3221/MAX3223
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
MAX3221/3223-03
LOAD CAPACITANCE (pF)
MAX3223 SUPPLY CURRENT (mA)
MAX3221 SUPPLY CURRENT (mA)
2000
3000
1000
4000
5000
235kbps
120kbps
20kbps
-7.5
-5.0
-2.5
0
2.5
5.0
7.5
0
MAX3243
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3221/3223-04
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
2000
3000
1000
4000
5000
V
OUT
+
1 TRANSMITTER AT 235kbps
2 TRANSMITTERS AT 30kbps
V
OUT
-
ALL OUTPUTS LOADED WITH 3k
+C
L
0.1
F CHARGE-PUMP CAPACITORS
FOR ALL DATA RATES UP TO 235kbps
4
6
8
10
12
14
16
18
20
22
24
0
MAX3243
SLEW RATE
vs. LOAD CAPACITANCE
MAX3221/3223-05
LOAD CAPACITANCE (pF)
SLEW RATE (V/
s)
2000
3000
1000
4000
5000
+SLEW
-SLEW
0
5
10
15
20
25
30
35
45
40
0
MAX3243
SUPPLY CURRENT vs. LOAD
CAPACITANCE WHEN TRANSMITTING DATA
MAX3221/3223-06
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
2000
3000
1000
4000
5000
235kbps
120kbps
20kbps
MAX3221/MAX3223/MAX3243
1A Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________
5
______________________________________________________________Pin Description
Noninverting Receiver Output--active in shutdown
R2OUTB
Output of the valid signal detector. Indicates if a valid RS-232 level is pres-
ent on receiver inputs logic "1".
INVALID
Drive low to shut down transmitters and on-board power supply. This over-
rides all automatic circuitry and FORCEON (Table 1).
FORCEOFF
Drive high to override automatic circuitry keeping transmitters on
(FORCEOFF must be high) (Table 1).
FORCEON
Negative terminal of the voltage doubler charge-pump capacitor
C1-
RS-232 Receiver Inputs
R_IN
RS-232 Transmitter Outputs
T_OUT
TTL/CMOS Transmitter Inputs
T_IN
TTL/CMOS Receiver Outputs
R_OUT
-5.5V generated by the charge pump
V-
Negative terminal of inverting charge-pump capacitor
C2-
Positive terminal of inverting charge-pump capacitor
C2+
Receiver Enable Control. Drive low for normal operation. Drive high to force
the receiver outputs into a high-Z state.
EN
FUNCTION
Ground
GND
+3.0V to +5.5V Supply Voltage
V
CC
LapLink is a trademark of Traveling Software.
_______________Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3221/MAX3223/MAX3243's internal power
supply consists of a regulated dual charge pump that
provides output voltages of +5.5V (doubling charge
pump) and -5.5V (inverting charge pump), regardless
of the input voltage (V
CC
) over the +3.0V to +5.5V
range. The charge pumps operate in a discontinuous
mode: if the output voltages are less than 5.5V, the
charge pumps are enabled; if the output voltages
exceed 5.5V, the charge pumps are disabled. Each
charge pump requires a flying capacitor (C1, C2) and
a reservoir capacitor (C3, C4) to generate the V+ and
V- supplies.
RS-232 Transmitters
The transmitters are inverting level translators that con-
vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They
guarantee a 120kbps data rate with worst-case loads of
3k
in parallel with 1000pF, providing compatibility with
PC-to-PC communication software (such as LaplinkTM).
Typically, the MAX3221/MAX3223/MAX3243 can oper-
ate at data rates of 235kbps. Transmitters can be paral-
leled to drive multiple receivers or mice (MAX3243).
Figure 1 shows a complete system connection.
When FORCEOFF is driven to ground, or the Auto-
Shutdown circuitry senses invalid voltage levels at all
receiver inputs, the transmitters are disabled and the
outputs are forced into a high-impedance state.
--
10
16
12
4
8
13
11
9
7
6
5
1
14
15
NAME
MAX3221
+5.5V generated by the charge pump
V+
3
Positive terminal of the voltage doubler charge-pump capacitor
C1+
2
--
11
20
14
4
9, 16
8, 17
12, 13
10, 15
7
6
5
1
18
19
20
21
22
23
24
48
9, 10, 11
12, 13, 14
1519
3
2
1
--
25
26
MAX3223
3
MAX3243
27
2
28
PIN
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