19-0306; Rev 6; 3/99
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
_______________General Description
The MAX3221/MAX3223/MAX3243 achieve 1µA supply
current with Maxim’s revolutionary AutoShutdown™ 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 0.1µF
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
1µA Supply Current Achieved with AutoShutdown
o
Small 0.1µF 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/µs Min Guaranteed Slew Rate
o
Smallest Single-Supply RS-232 Transceiver
(MAX3221)
o
Guaranteed Mouse Driveability (MAX3243)
o
Small TSSOP Package (MAX3223/MAX3243)
MAX3221/MAX3223/MAX3243*
________________________Applications
Notebook, Subnotebook, and Palmtop Computers
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers
______________Ordering Information
PART
MAX3221CAE
MAX3221CUE†
MAX3221EAE
MAX3221EUE†
MAX3223CPP
MAX3223CAP
MAX3223CUP
MAX3223EPP
MAX3223EAP
MAX3223EUP
MAX3243CWI
MAX3243CAI
MAX3243CUI
MAX3243EWI
MAX3243EAI
MAX3243EUI
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 SSOP
16 TSSOP
16 SSOP
16 TSSOP
20 Plastic DIP
20 SSOP
20 TSSOP
20 Plastic DIP
20 SSOP
20 TSSOP
28 Wide SO
28 SSOP
28 TSSOP
28 Wide SO
28 SSOP
28 TSSOP
_____________________Selector Guide
PART
MAX3221
MAX3223
MAX3243
Tx
1
2
3
Rx
1
2
5
V
CC
RANGE (V) AutoShutdown
3.0 to 5.5
3.0 to 5.5
3.0 to 5.5
Yes
Yes
Yes
Pin Configurations appear at end of data sheet.
Typical Operating Circuits appear at end of data sheet.
†Future
product—contact factory for availability.
AutoShutdown is a trademark of Maxim Integrated Products.
* 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.
________________________________________________________________
Maxim Integrated Products
1
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.
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
MAX3221/MAX3223/MAX3243
ABSOLUTE MAXIMUM RATINGS
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
= +70°C)
16-Pin SSOP (derate 7.14mW/°C above +70°C) ...........571mW
16-Pin TSSOP (derate 6.70mW/°C above +70°C) .........533mW
20-Pin Plastic DIP (derate 11.11mW/°C above +70°C)....889mW
20-Pin SSOP (derate 8.00mW/°C above +70°C) ...........640mW
20-Pin TSSOP DIP (derate 7.00mW/°C above +70°C).....559mW
28-Pin Wide SO (derate 12.50mW/°C above +70°C) ............1W
28-Pin SSOP (derate 9.52mW/°C above +70°C) ...........762mW
28-Pin TSSOP (derate 8.70mW/°C above +70°C) .........696mW
Operating Temperature Ranges
MAX32_ _C_ _.......................................................0°C to +70°C
MAX32_ _E_ _ ....................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
Note 1:
V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
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
(V
CC
= +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
DC CHARACTERISTICS
Supply Current, AutoShutdown
Supply Current, Shutdown
Supply Current,
AutoShutdown Disabled
Input Logic Threshold Low
Input Logic Threshold High
Input Leakage Current
Output Leakage Current
Output Voltage Low
Output Voltage High
All R_IN open, FORCEON = GND,
V
CC
= 3.3V
FORCEOFF
= V
CC
or 5.0V,
FORCEOFF
= GND
T
A
= +25°C FORCEON =
FORCEOFF
= V ,
CC
CONDITIONS
MIN
TYP
MAX
UNITS
1.0
1.0
0.3
10
10
1.0
µA
µA
mA
no load
T_IN, FORCEON,
FORCEOFF, EN
(MAX3223)
T_IN, EN, FORCEON,
FORCEOFF
T_IN, EN, FORCEON,
FORCEOFF
Receivers disabled
I
OUT
= 1.6mA
I
OUT
= -1.0mA
Positive threshold
Negative threshold
-2.7
-0.3
V
CC
- 0.6
V
CC
= 3.3V
V
CC
= 5.0V
2.0
2.4
LOGIC INPUTS AND RECEIVER OUTPUTS
0.8
V
V
±0.01
±0.05
±1.0
±10
0.4
V
CC
- 0.1
2.7
µA
µA
V
V
AUTOSHUTDOWN
(FORCEON = GND,
FORCEOFF
= V
CC
)
Receiver Input Thresholds to
Transmitters Enabled
Receiver Input Thresholds to
Transmitters Disabled
INVALID
Output Voltage Low
INVALID
Output Voltage High
Receiver Threshold to
Transmitters Enabled (t
WU
)
Receiver Positive or Negative
Threshold to
INVALID
High (t
INVH
)
Receiver Positive or Negative
Threshold to
INVALID
Low (t
INVL
)
2
Figure 5
V
V
V
V
250
1
30
µs
µs
µs
1µA supply current, Figure 5
I
OUT
= 1.6mA
I
OUT
= -1.0mA
Figure 5
Figure 5
Figure 5
0.3
0.4
V
CC
- 0.6
_______________________________________________________________________________________
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
RECEIVER INPUTS
Input Voltage Range
Input Threshold Low
Input Threshold High
Input Hysteresis
Input Resistance
TRANSMITTER OUTPUTS
Output Voltage Swing
Output Resistance
Output Short-Circuit Current
Output Leakage Current
V
OUT
= ±12V, V
CC
= 0V or 3.0V to 5.5V,
transmitters disabled
All transmitter outputs loaded with 3kΩ to ground
V
CC
= V+ = V- = 0V, transmitter output = ±2V
±5.0
300
±5.4
10M
±35
±60
±25
V
Ω
mA
µA
T
A
= +25°C
3
T
A
= +25°C
T
A
= +25°C
V
CC
= 3.3V
V
CC
= 5.0V
V
CC
= 3.3V
V
CC
= 5.0V
-25
0.6
0.8
1.2
1.5
1.5
1.8
0.3
5
7
2.4
2.4
25
V
V
V
V
kΩ
CONDITIONS
MIN
TYP
MAX
UNITS
MAX3221/MAX3223/MAX3243
MOUSE DRIVEABILITY
(MAX3243)
Transmitter Output Voltage
TIMING CHARACTERISTICS
Maximum Data Rate
Receiver Propagation Delay
Receiver Output Enable Time
Receiver Output Disable Time
Transmitter Skew
Receiver Skew
R
L
= 3kΩ, C
L
= 1000pF, one transmitter switching
Receiver input to receiver output,
C
L
= 150pF
Normal operation
Normal operation
t
PHL
- t
PLH
t
PHL
- t
PLH
V
CC
= 3.3V,
R
L
= 3kΩ to 7kΩ,
T
A
= +25°C,
measured from +3V to
-3V or -3V to +3V
MAX3221/MAX3223
MAX3243
MAX3221/MAX3223
MAX3243
C
L
= 200pF to 2500pF
4
t
PHL
t
PLH
120
235
0.3
0.3
200
200
200
200
100
100
8.0
500
30
V/µs
C
L
= 200pF to 1000pF
6
30
1000
kbps
µs
ns
ns
ns
ns
T1IN = T2IN = GND, T3IN = V
CC
,
T3OUT loaded with 3kΩ to GND, T1OUT and
T2OUT loaded with 2.5mA each
±5
V
Transition-Region Slew Rate
Note 2:
C1–C4 = 0.1µF, tested at 3.3V ±10%. C1 = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%.
_______________________________________________________________________________________
3
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
MAX3221/MAX3223/MAX3243
__________________________________________Typical Operating Characteristics
(V
CC
= +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, T
A
= +25°C, unless otherwise noted.)
MAX3221/MAX3223
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3221/3223-01
MAX3221/MAX3223
SLEW RATE
vs. LOAD CAPACITANCE
MAX3223 SUPPLY CURRENT (mA)
20
18
SLEW RATE (V/µs)
16
14
12
10
8
6
4
2
+SLEW
-SLEW
MAX3221/3223-02
MAX3221/MAX3223
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
40
35
235kbps
30
25
20
15
10
5
20kbps
120kbps
25
20
15
10
5
0
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
MAX3221/3223-03
4
3
2
1
0
-1
-2
-3
-4
-5
-6
0
1000
2000
3000
4000
V
OUT-
30
FOR DATA RATES UP TO 235kbps
5000
0
150 500 1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3243
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3221/3223-04
MAX3243
SLEW RATE
vs. LOAD CAPACITANCE
MAX3221/3223-05
MAX3243
SUPPLY CURRENT vs. LOAD
CAPACITANCE WHEN TRANSMITTING DATA
40
SUPPLY CURRENT (mA)
35
30
25
20
15
10
5
0
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
20kbps
120kbps
235kbps
MAX3221/3223-06
7.5
TRANSMITTER OUTPUT VOLTAGE (V)
V
OUT
+
5.0
2.5
0
-2.5
-5.0
-7.5
0
1000
2000
3000
4000
V
OUT
-
24
22
20
SLEW RATE (V/µs)
18
16
14
12
10
8
6
4
+SLEW
ALL OUTPUTS LOADED WITH 3kΩ +C
L
0.1µF CHARGE-PUMP CAPACITORS
FOR ALL DATA RATES UP TO 235kbps
0
1000
2000
3000
4000
-SLEW
45
1 TRANSMITTER AT 235kbps
2 TRANSMITTERS AT 30kbps
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
4
_______________________________________________________________________________________
MAX3221 SUPPLY CURRENT (mA)
6
5
TRANSMITTER OUTPUT VOLTAGE (V)
22
35
V
OUT+
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
______________________________________________________________Pin Description
PIN
MAX3221
1
5
6
7
8
13
11
9
—
10
16
12
4
14
15
3
2
MAX3223
1
5
6
7
9, 16
8, 17
12, 13
10, 15
—
11
20
14
4
18
19
3
2
MAX3243
—
1
2
3
4–8
9, 10, 11
12, 13, 14
15–19
20
21
22
23
24
25
26
27
28
NAME
EN
C2+
C2-
V-
R_IN
T_OUT
T_IN
R_OUT
R2OUTB
INVALID
FORCEOFF
FORCEON
C1-
GND
V
CC
V+
C1+
FUNCTION
Receiver Enable Control. Drive low for normal operation. Drive high to force
the receiver outputs into a high-Z state.
Positive terminal of inverting charge-pump capacitor
Negative terminal of inverting charge-pump capacitor
-5.5V generated by the charge pump
RS-232 Receiver Inputs
RS-232 Transmitter Outputs
TTL/CMOS Transmitter Inputs
TTL/CMOS Receiver Outputs
Noninverting Receiver Output—active in shutdown
Output of the valid signal detector. Indicates if a valid RS-232 level is pres-
ent on receiver inputs logic “1”.
Drive low to shut down transmitters and on-board power supply. This over-
rides all automatic circuitry and FORCEON (Table 1).
Drive high to override automatic circuitry keeping transmitters on
(FORCEOFF must be high) (Table 1).
Negative terminal of the voltage doubler charge-pump capacitor
Ground
+3.0V to +5.5V Supply Voltage
+5.5V generated by the charge pump
Positive terminal of the voltage doubler charge-pump capacitor
MAX3221/MAX3223/MAX3243
_______________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
3kΩ in parallel with 1000pF, providing compatibility with
PC-to-PC communication software (such as Laplink™).
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.
LapLink is a trademark of Traveling Software.
_______________________________________________________________________________________
5
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