MAXIM MAX3243CAI

19-0306; Rev 6; 3/99
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
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 version 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 biasing the protection diodes in a UART that may have VCC
completely removed.
MAX3221
Tx
1
Rx
1
♦ Small 0.1µF Capacitors
♦ True RS-232 Operation from VCC = +3.0V to +5.5V
♦ Meets EIA/TIA-562 Specifications Down to 2.7V
♦ Guaranteed 120kbps Data Rate
♦ 6V/µs Min Guaranteed Slew Rate
♦ Smallest Single-Supply RS-232 Transceiver
(MAX3221)
♦ Guaranteed Mouse Driveability (MAX3243)
♦ Small TSSOP Package (MAX3223/MAX3243)
________________________Applications
Notebook, Subnotebook, and Palmtop Computers
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers
______________Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX3221CAE
0°C to +70°C
16 SSOP
0°C to +70°C
16 TSSOP
MAX3221CUE†
MAX3221EAE
-40°C to +85°C
MAX3221EUE†
-40°C to +85°C
16 SSOP
16 TSSOP
0°C to +70°C
20 Plastic DIP
MAX3223CAP
0°C to +70°C
20 SSOP
MAX3223CUP
0°C to +70°C
20 TSSOP
Yes
MAX3223EPP
-40°C to +85°C
20 Plastic DIP
-40°C to +85°C
20 SSOP
20 TSSOP
VCC RANGE (V) AutoShutdown
3.0 to 5.5
♦ 1µA Supply Current Achieved with AutoShutdown
MAX3223CPP
_____________________Selector Guide
PART
____________________________Features
MAX3223
2
2
3.0 to 5.5
Yes
MAX3223EAP
MAX3243
3
5
3.0 to 5.5
Yes
MAX3223EUP
-40°C to +85°C
MAX3243CWI
0°C to +70°C
28 Wide SO
MAX3243CAI
0°C to +70°C
28 SSOP
MAX3243CUI
0°C to +70°C
28 TSSOP
MAX3243EWI
-40°C to +85°C
28 Wide SO
MAX3243EAI
-40°C to +85°C
28 SSOP
MAX3243EUI
-40°C to +85°C
28 TSSOP
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.
MAX3221/MAX3223/MAX3243*
_______________General Description
The MAX3221/MAX3223/MAX3243 achieve 1µA supply
current with Maxim’s revolutionary AutoShutdown™ feature. 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 3Vpowered EIA/TIA-232 and V.28/V.24 communications
interfaces intended for notebook computer applications. 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 provides compatibility with popular software for communicating with personal computers.
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
ABSOLUTE MAXIMUM RATINGS
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
VCC ...........................................................................-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 (VCC + 0.3V)
Short-Circuit Duration
T_OUT ......................................................................Continuous
Continuous Power Dissipation (TA = +70°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
(VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
1.0
10
µA
1.0
10
µA
0.3
1.0
mA
0.8
V
DC CHARACTERISTICS
Supply Current, AutoShutdown
Supply Current, Shutdown
Supply Current,
AutoShutdown Disabled
All R_IN open, FORCEON = GND,
VCC = 3.3V FORCEOFF = VCC
or 5.0V,
FORCEOFF = GND
TA = +25°C FORCEON = FORCEOFF = V ,
CC
no load
LOGIC INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
T_IN, FORCEON, FORCEOFF, EN (MAX3223)
VCC = 3.3V
2.0
VCC = 5.0V
2.4
Input Logic Threshold High
T_IN, EN, FORCEON, FORCEOFF
Input Leakage Current
T_IN, EN, FORCEON, FORCEOFF
±0.01
±1.0
µA
Output Leakage Current
Receivers disabled
±0.05
±10
µA
Output Voltage Low
IOUT = 1.6mA
0.4
V
Output Voltage High
IOUT = -1.0mA
VCC - 0.6
V
VCC - 0.1
V
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)
Positive threshold
Receiver Input Thresholds to
Transmitters Enabled
Figure 5
Receiver Input Thresholds to
Transmitters Disabled
1µA supply current, Figure 5
INVALID Output Voltage Low
IOUT = 1.6mA
INVALID Output Voltage High
IOUT = -1.0mA
Receiver Threshold to
Transmitters Enabled (tWU)
Receiver Positive or Negative
Threshold to INVALID High (tINVH)
Receiver Positive or Negative
Threshold to INVALID Low (tINVL)
2
Negative threshold
2.7
-2.7
-0.3
VCC - 0.6
V
0.3
V
0.4
V
V
Figure 5
250
µs
Figure 5
1
µs
Figure 5
30
µs
_______________________________________________________________________________________
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
(VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
25
V
RECEIVER INPUTS
Input Voltage Range
-25
Input Threshold Low
TA = +25°C
Input Threshold High
TA = +25°C
VCC = 3.3V
0.6
1.2
VCC = 5.0V
0.8
1.5
V
VCC = 3.3V
1.5
2.4
VCC = 5.0V
1.8
2.4
Input Hysteresis
0.3
Input Resistance
TA = +25°C
3
5
V
V
7
kΩ
TRANSMITTER OUTPUTS
Output Voltage Swing
All transmitter outputs loaded with 3kΩ to ground
±5.0
±5.4
Output Resistance
VCC = V+ = V- = 0V, transmitter output = ±2V
300
10M
Output Short-Circuit Current
Output Leakage Current
±35
VOUT = ±12V, VCC = 0V or 3.0V to 5.5V,
transmitters disabled
V
Ω
±60
mA
±25
µA
MOUSE DRIVEABILITY (MAX3243)
Transmitter Output Voltage
T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩ to GND, T1OUT and
T2OUT loaded with 2.5mA each
±5
RL = 3kΩ, CL = 1000pF, one transmitter switching
120
V
TIMING CHARACTERISTICS
Maximum Data Rate
235
tPHL
0.3
tPLH
0.3
kbps
Receiver Propagation Delay
Receiver input to receiver output,
CL = 150pF
Receiver Output Enable Time
Normal operation
200
ns
Receiver Output Disable Time
Normal operation
200
ns
Transmitter Skew
Receiver Skew
Transition-Region Slew Rate
µs
 tPHL - tPLH 
MAX3221/MAX3223
200
MAX3243
200
 tPHL - tPLH 
MAX3221/MAX3223
100
MAX3243
100
500
8.0
30
VCC = 3.3V,
RL = 3kΩ to 7kΩ,
TA = +25°C,
measured from +3V to
-3V or -3V to +3V
CL = 200pF to 2500pF
4
1000
ns
ns
V/µs
CL = 200pF to 1000pF
6
30
Note 2: C1–C4 = 0.1µF, tested at 3.3V ±10%. C1 = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%.
_______________________________________________________________________________________
3
MAX3221/MAX3223/MAX3243
ELECTRICAL CHARACTERISTICS (continued)
__________________________________________Typical Operating Characteristics
(VCC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA = +25°C, unless otherwise noted.)
20
18
SLEW RATE (V/µs)
4
3
2
1
0
-1
-2
-3
MAX3221/3223-02
VOUT+
16
14
-SLEW
12
10
+SLEW
8
6
-4
4
VOUT-
FOR DATA RATES UP TO 235kbps
35
35
30
235kbps
30
25
25
20
120kbps
20
15
15
10
20kbps
10
5
2
1000
2000
3000
4000
4000
MAX3243
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3243
SLEW RATE
vs. LOAD CAPACITANCE
22
20
1 TRANSMITTER AT 235kbps
2 TRANSMITTERS AT 30kbps
-2.5
VOUT-
-5.0
18
14
12
+SLEW
ALL OUTPUTS LOADED WITH 3kΩ +CL
0.1µF CHARGE-PUMP CAPACITORS
FOR ALL DATA RATES UP TO 235kbps
6
4
-7.5
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
5000
0
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
2000
3000
4000
5000
MAX3243
SUPPLY CURRENT vs. LOAD
CAPACITANCE WHEN TRANSMITTING DATA
-SLEW
8
1000
LOAD CAPACITANCE (pF)
16
10
0
0
5000
MAX3221/3223-05
24
SLEW RATE (V/µs)
5.0
0
3000
LOAD CAPACITANCE (pF)
VOUT+
0
5
2000
LOAD CAPACITANCE (pF)
7.5
2.5
0
150 500 1000
5000
MAX3221/3223-04
0
45
235kbps
40
35
30
MAX3221/3223-06
-6
SUPPLY CURRENT (mA)
-5
4
MAX3221/3223-03
40
MAX3223 SUPPLY CURRENT (mA)
22
MAX3221/3223-01
TRANSMITTER OUTPUT VOLTAGE (V)
6
5
MAX3221/MAX3223
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
MAX3221/MAX3223
SLEW RATE
vs. LOAD CAPACITANCE
120kbps
25
20
20kbps
15
10
5
0
5000
0
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
_______________________________________________________________________________________
5000
MAX3221 SUPPLY CURRENT (mA)
MAX3221/MAX3223
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
PIN
NAME
FUNCTION
—
EN
Receiver Enable Control. Drive low for normal operation. Drive high to force
the receiver outputs into a high-Z state.
5
1
C2+
Positive terminal of inverting charge-pump capacitor
6
2
C2-
Negative terminal of inverting charge-pump capacitor
7
7
3
V-
8
9, 16
4–8
R_IN
13
8, 17
9, 10, 11
T_OUT
11
12, 13
12, 13, 14
T_IN
TTL/CMOS Transmitter Inputs
9
10, 15
15–19
R_OUT
TTL/CMOS Receiver Outputs
—
—
20
R2OUTB
Noninverting Receiver Output—active in shutdown
10
11
21
INVALID
Output of the valid signal detector. Indicates if a valid RS-232 level is present on receiver inputs logic “1”.
16
20
22
FORCEOFF
Drive low to shut down transmitters and on-board power supply. This overrides all automatic circuitry and FORCEON (Table 1).
12
14
23
FORCEON
Drive high to override automatic circuitry keeping transmitters on
(FORCEOFF must be high) (Table 1).
4
4
24
C1-
Negative terminal of the voltage doubler charge-pump capacitor
14
18
25
GND
Ground
15
19
26
VCC
+3.0V to +5.5V Supply Voltage
3
3
27
V+
+5.5V generated by the charge pump
2
2
28
C1+
MAX3221
MAX3223
MAX3243
1
1
5
6
-5.5V generated by the charge pump
RS-232 Receiver Inputs
RS-232 Transmitter Outputs
Positive terminal of the voltage doubler charge-pump capacitor
_______________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 convert 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 operate at data rates of 235kbps. Transmitters can be paralleled to drive multiple receivers or mice (MAX3243).
Figure 1 shows a complete system connection.
When FORCEOFF is driven to ground, or the AutoShutdown 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
MAX3221/MAX3223/MAX3243
______________________________________________________________Pin Description
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
POWER
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER
FORCEOFF
VCC
FORCEON
INVALID
PROTECTION
DIODE
PREVIOUS
RS-232
MAX3243
VCC
I
Rx
5k
UART
Tx
CPU
I/O
CHIP
WITH
UART
GND
SHDN = GND
RS-232
(a)
OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE
RECEIVER OUTPUT IN SHUTDOWN.
VCC
TO
µP
LOGIC
TRANSITION
DETECTOR
Figure 1. Interface Under Control of PMU
I
PROTECTION
DIODE
RS-232 Receivers
The MAX3221/MAX3223/MAX3243’s receivers convert
RS-232 signals to CMOS-logic output levels. All
receivers have one inverting three-state output. In shutdown (FORCEOFF = low) or in AutoShutdown, the
MAX3221/MAX3223’s receivers are active (Table 1).
Driving EN high places the receiver(s) in a high-impedance state. The MAX3243’s receivers are high impedance when the part is shut down.
The MAX3243 has an always-active complementary
output (R2OUTB). R2OUTB is an extra output that monitors receiver 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 VCC is
set to 0V in shutdown to accommodate peripherals,
such as UARTs (Figure 2).
6
MAX3243
R2OUTB
VCC
Rx
THREE-STATED
UART
5k
Tx
GND
(b)
R2IN
R2OUT
T1IN
FORCEOFF = GND
NEW MAX3243: IN SHUTDOWN, R2OUTB IS USED TO MONITOR EXTERNAL
DEVICES AND R2OUT IS THREE STATED, ELIMINATING A CURRENT PATH
THROUGH THE UART'S PROTECTION DIODE.
Figure 2. The MAX3243 detects RS-232 activity when the
UART and interface are shut down.
_______________________________________________________________________________________
T1OUT
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
FORCEOFF
EN
T_OUT
R_OUT
0
0
High-Z
Active
0
1
High-Z
1
0
Active*
High-Z
Active
1
1
Active*
High-Z
MAX3221/MAX3223/MAX3243
Table 1a. MAX3221/MAX3223 FORCEOFF and
Enable Control Truth Table
+0.3V
R_IN
30µs
COUNTER
R
-0.3V
TO MAX32_ _
POWER SUPPLY
AND TRANSMITTERS
INVALID
* TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1µA IF
ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µs.
Figure 3a. MAX32_ _ Entering 1µA Supply Mode via
AutoShutdown
Table 1b. MAX3243 FORCEOFF Control
Truth Table
FORCEOFF
T_OUT
R_OUT
R2OUTB
0
High-Z
High-Z
Active
1
Active*
Active*
Active
*Note: If the part is in AutoShutdown mode (FORCEOFF = VCC,
FORCEON = GND), it is shut down if no valid RS-232
levels are present on all receiver inputs.
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
MAX3221/MAX3223/MAX3243 sense no valid signal
levels on all receiver inputs for 30µs, the on-board
power supply and drivers are shut off, reducing supply
current to 1µA. This occurs if the RS-232 cable is disconnected or 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 AutoShutdown,
the INVALID output is high when the device is on and
low when the device is shut down. Because INVALID
indicates the receiver inputs’ condition, it can be used
in any mode (Figure 3).
Table 2 and Figure 3c summarize the MAX3221/
MAX3223/MAX3243 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. Figures 3a, 3b, and 5a
depict valid and invalid RS-232 receiver levels.
A mouse or other system with AutoShutdown may need
time to wake up. Figure 4 shows a circuit that forces the
transmitters on for 100ms, allowing enough time for the
+2.7V
R_IN
TO MAX32_ _
POWER SUPPLY
30µs
COUNTER
R
-2.7V
INVALID
* TRANSMITTERS ARE ENABLED IF:
ANY RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V.
ANY RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR LESS THAN 30µs.
Figure 3b. MAX32_ _ with Transmitters Enabled Using
AutoShutdown
FORCEOFF
POWER DOWN
FORCEON
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.
Figure 3c. AutoShutdown Logic
POWER
MANAGEMENT
UNIT
MASTER SHDN LINE
0.1µF
1M
FORCEOFF FORCEON
MAX3221
MAX3223
MAX3243
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
_______________________________________________________________________________________
7
Table 2. AutoShutdown Logic
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)
other system to realize that the MAX3221/MAX3223/
MAX3243 is awake. If the other system outputs valid
RS-232 signals within that time, the RS-232 ports on
both systems remain enabled.
When shut down, the device’s charge pumps are turned
off, V+ decays to VCC, V- decays to ground, and the
transmitter outputs are disabled (high impedance). The
time required to exit shutdown is typically 100µs (Figure
5b).
TRANSMITTERS ENABLED, INVALID HIGH
RECEIVER INPUT LEVELS
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
+2.7V
INDETERMINATE
+0.3V
0V
-0.3V
INDETERMINATE
Software-Controlled Shutdown
If direct software control is desired, INVALID can be
used to indicate DTR or Ring Indicator signal. Tie
FORCEOFF and FORCEON together to bypass AutoShutdown so the line acts like a SHDN input.
AUTOSHUTDOWN, TRANSMITTERS DISABLED,
1µA SUPPLY CURRENT, INVALID LOW
-2.7V
TRANSMITTERS ENABLED, INVALID HIGH
(a)
___________Applications Information
Capacitor Selection
The capacitor type used for C1–C4 is not critical for
proper operation; either polarized or nonpolarized
capacitors may be used. The charge pump requires
0.1µF capacitors for 3.3V operation. For other supply
voltages, refer to Table 3 for required capacitor values.
Do not use values smaller than those listed in Table 3.
Increasing the capacitor values (e.g., by a factor of 2)
reduces ripple on the transmitter outputs and slightly
reduces power consumption. C2, C3, and C4 can be
increased without changing C1’s value. However, do
not increase C1 without also increasing the values
of C2, C3, and C4 to maintain the proper ratios (C1
to the other capacitors).
When using the minimum required capacitor values,
make sure the capacitor value does not degrade
excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor’s equivalent series resistance (ESR) usually rises at
low temperatures and influences the amount of ripple
on V+ and V-.
8
RECEIVER
INPUT
VOLTAGE
(V)
INVALID
REGION
VCC
INVALID
OUTPUT
(V)
0
tINVL
tINVH
tWU
V+
VCC
0
V-
(b)
Figure 5. AutoShutdown Trip Levels
_______________________________________________________________________________________
2V/div
T1
50µs/div
4
3
T1
0
-1
T2
VOUT+
-2
-3
VCC
VOUT-
T3
VOUT-
-4
-5
-6
0
VCC = +3.3V
C1–C4 = 0.1µF
VOUT+
VCC = 3.0V
2
1
MAX3222-04
T2
6
5
1
2
3
4
5
6
7
LOAD CURRENT PER TRANSMITTER (mA)
Figure 6. Transmitter Outputs when Exiting Shutdown or
Powering Up
Power-Supply Decoupling
In most circumstances a 0.1µF bypass capacitor is
adequate. In applications that are sensitive to powersupply noise, decouple VCC to ground with a capacitor
of the same value as the charge-pump capacitor C1.
Connect bypass capacitors as close to the IC as possible.
Transmitter Outputs
when Exiting Shutdown
Figure 6 shows two transmitter outputs when exiting
shutdown mode. As they become active, the two transmitter outputs are shown going to opposite RS-232
levels. Each transmitter is loaded with 3kΩ in parallel
with 2500pF. The transmitter outputs display no ringing
or undesirable transients as they come out of shutdown. Note that the transmitters are enabled only when
the magnitude of V- exceeds approximately 3V. Figure
7a shows the MAX3243’s transmitter output voltage
vs. current per transmitter. Figure 7b is a mouse driver
test circuit.
Figure 7a. MAX3243 Transmitter Output Voltage vs. Load
Current per Transmitter
Microsoft. The MAX3243 successfully drove all serial
mice and met their respective current and voltage
requirements. Figure 7a shows the transmitter outputs
under increasing load current. The MAX3243’s switching
regulator ensures the transmitters will supply at least ±5V
during worst-case conditions. The AutoShutdown feature
does not work with a mouse, so FORCEOFF and
FORCEON should be connected to VCC.
High Data Rates
The MAX3221/MAX3223/MAX3243 maintain the RS-232
±5.0V minimum transmitter output voltage even at high
data rates. Figure 8 shows a transmitter loopback test
circuit. Figure 9 shows a loopback test result at
120kbps, and Figure 10 shows the same test at
235kbps. For Figure 9, all three transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 10, a single transmitter
was driven at 235kbps, but all three transmitters were
loaded with an RS-232 receiver in parallel with 1000pF.
Mouse Driveability (MAX3243)
Interconnection with 3V and 5V Logic
The MAX3243 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
The MAX3221/MAX3223/MAX3243 can directly interface with various 5V logic families, including ACT and
HCT CMOS. See Table 4 for more information on possible combinations of interconnections.
_______________________________________________________________________________________
9
MAX3221/MAX3223/MAX3243
5V/div
TRANSMITTER OUTPUT VOLTAGE (V)
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
+3.3V
26
0.1µF
28
C1
0.1µF
24
1
C2
0.1µF
2
LOGIC
INPUTS
VCC
27
C1+
V+
C3
0.1µF
C1C2+
COMPUTER SERIAL PORT
3
MAX3243
V-
C4
0.1µF
C2-
14
T1IN
T1OUT
9
+V
13
T2IN
T2OUT
10
+V
12
T3IN
T3OUT
11
-V
20
R2OUTB
19
R1OUT
GND
R1IN
4
R2IN
5
R3IN
6
R4IN
7
R5IN
8
Tx
5k
18
R2OUT
LOGIC
OUTPUTS
5k
17
R3OUT
RS-232
INPUTS
5k
16
R4OUT
5k
15
23
VCC
TO POWER
MANAGEMENT
UNIT
22
21
R5OUT
SERIAL
MOUSE
5k
FORCEON
FORCEOFF
INVALID
GND
25
Figure 7b. Mouse Driver Test Circuit
10
______________________________________________________________________________________
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
VCC
(V)
0.1µF
VCC
C1+
V+
C3
C1
C1
(µF)
C2, C3, C4
(µF)
3.0 to 3.6
0.1
0.1
4.5 to 5.5
0.047
0.33
3.0 to 5.5
0.1
0.47
C1C2+
MAX3221
MAX3223
MAX3243
C2
C2-
R_ IN
R_ OUT
VCC
C4
T_ OUT
T_ IN
0V
V-
EN (MAX3221/3)
FORCEOFF
5k
Table 4. Logic Family Compatibility with
Various Supply Voltages
SYSTEM
POWERSUPPLY
VOLTAGE
(V)
VCC SUPPLY
VOLTAGE
(V)
3.3
3.3
5
5
5
3.3
1000pF
GND
COMPATIBILITY
Compatible with all CMOS
families.
Compatible with all TTL and
CMOS-logic families.
Compatible with ACT and
HCT CMOS, and with TTL.
Incompatible with AC, HC,
or CD4000 CMOS.
Figure 8. Loopback Test Circuit
T1IN
5V/div
T1IN
5V/div
T1OUT
5V/div
T1OUT
5V/div
R1OUT
5V/div
R1OUT
5V/div
5µs/div
VCC = +3.3V, 120kbps
C1–C4 = 0.1µF
Figure 9. Loopback Test Result at 120kbps
2µs/div
VCC = +3.3V, 235kbps
C1–C4 = 0.1µF
Figure 10. Loopback Test Result at 235kbps
______________________________________________________________________________________
11
MAX3221/MAX3223/MAX3243
Table 3. Required Capacitor Values
VCC
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
__________________________________________________Typical Operating Circuits
+3.3V
15
0.1µF
C5
2 C1+
C1
0.1µF
4 C15
C2
0.1µF
6
VCC
3
V+
MAX3221
C2+
V-
C3
0.1µF
28 C1+
C1
0.1µF
T1OUT 13
24
1
C2
0.1µF
R1IN 8
9 R1OUT
2
5k
1 EN
12
INVALID 10
FORCEOFF 16
FORCEON
GND
TO POWER
MANAGEMENT
UNIT
LOGIC
INPUTS
TTL/CMOS
INPUTS
C2+
MAX3243
V-
2 C1+
4 C1-
6
14 T1IN
T1OUT 9
13 T2IN
T2OUT 10
12 T3IN
T3OUT 11
MAX3223
C2+
V-
C3
0.1µF
7
C2-
13 T1IN
T1OUT 17
12 T2IN
T2OUT 8
LOGIC
OUTPUTS
C4
0.1µF
17 R3OUT
R3IN 6
5k
R4IN 7
RS-232
OUTPUTS
5k
23
R1IN 16
RS-232
INPUTS
VCC
R2IN 9
TO POWER
MANAGEMENT UNIT
5k
1 EN
INVALID 11
FORCEOFF 20
FORCEON
GND
22
R5IN 8
5k
FORCEON
FORCEOFF
21 INVALID
GND
25
TO POWER
MANAGEMENT
UNIT
VCC
18
12
5
5k
16 R4OUT
5k
14
R2IN
15 R5OUT
10 R2OUT
RS-232
OUTPUTS
R1IN 4
18 R2OUT
3
V+
TTL/CMOS
OUTPUTS
C4
0.1µF
5k
VCC
15 R1OUT
3
C2-
19
0.1µF
C3
0.1µF
C1-
19 R1OUT
5
C2
0.1µF
27
V+
20 R2OUTB
+3.3V
C1
0.1µF
VCC
VCC
14
C5
26
0.1µF
C4
0.1µF
C2-
11 T1IN
+3.3V
7
______________________________________________________________________________________
RS-232
INPUTS
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
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
120
562
562
230kbps guaranteed data rate
0.1µF capacitors
MAX3212
2.7 to 3.6
3/5
5
235
232
AutoShutdown, complementary
receiver, drives mice, transient
detection
MAX3221
MAX3222
MAX3223
MAX3232
3.0 to 5.5
3.0 to 5.5
3.0 to 5.5
3.0 to 5.5
1/1
2/2
2/2
2/2
1
2
2
N/A
120
120
120
120
232
232
232
232
0.1µF capacitors, 16-pin SSOP
0.1µF capacitors, MAX242 pinout
0.1µF capacitors, AutoShutdown
0.1µF capacitors, MAX232 pinout
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
FEATURES
______________________________________________________________________________________
13
MAX3221/MAX3223/MAX3243
______3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
__________________________________________________________Pin Configurations
TOP VIEW
EN 1
EN 1
16 FORCEOFF
C1+ 2
15 VCC
V+ 3
14 GND
C1- 4
MAX3221
13 T1OUT
V+ 3
18 GND
C2+ 5
12 FORCEON
C2- 6
11 T1IN
C2- 6
V- 7
10 INVALID
C2+ 1
28 C1+
C2- 2
27 V+
V- 3
26 VCC
R1IN 4
25 GND
R2IN 5
MAX3243
R3IN 6
16 R1IN
15 R1OUT
14 FORCEON
13 T1IN
R2IN 9
12 T2IN
R2OUT 10
SSOP/TSSOP
17 T1OUT
MAX3223
T2OUT 8
9 R1OUT
R1IN 8
19 VCC
C1- 4
C2+ 5
V- 7
20 FORCEOFF
C1+ 2
11 INVALID
DIP/SSOP/TSSOP
24 C123 FORCEON
R4IN 7
22 FORCEOFF
R5IN 8
21 INVALID
T1OUT 9
20 R2OUTB
T2OUT 10
19 R1OUT
T3OUT 11
18 R2OUT
T3IN 12
17 R3OUT
T2IN 13
16 R4OUT
T1IN 14
15 R5OUT
SO/SSOP/TSSOP
___________________Chip Information
MAX3221
TRANSISTOR COUNT: 269
MAX3223
TRANSISTOR COUNT: 339
MAX3243
TRANSISTOR COUNT: 476
14
______________________________________________________________________________________
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
TSSOP.EPS
SSOP.EPS
______________________________________________________________________________________
15
MAX3221/MAX3223/MAX3243
________________________________________________________Package Information
SOICW.EPS
___________________________________________Package Information (continued)
PDIPN.EPS
MAX3221/MAX3223/MAX3243
1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.