AutoShutdownPlus, MegaBaud, and UCSP are trademarks
of Maxim Integrated Products, Inc.
†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; 5,649,210; and other patents pending.
19-1289; Rev 2; 10/03
________________General Description
The MAX3224–MAX3227/MAX3244/MAX3245 are 3V-
powered EIA/TIA-232 and V.28/V.24 communications
interfaces with automatic shutdown/wakeup features
and high data-rate capabilities.
All devices achieve a 1µA supply current using Maxim’s
revolutionary AutoShutdown Plus™ feature. These
devices automatically enter a low-power shutdown
mode when the RS-232 cable is disconnected or the
transmitters of the connected peripherals are inactive,
and the UART driving the transmitter inputs is inactive
for more than 30 seconds. They turn on again when
they sense a valid transition at any transmitter or receiv-
er input. AutoShutdown Plus saves power without
changes to the existing BIOS or operating system.
The MAX3225/MAX3227/MAX3245 also feature
MegaBaud™ operation, guaranteeing 1Mbps for high-
speed applications such as communicating with ISDN
modems. The MAX3224/MAX3226/MAX3244 guarantee
250kbps operation. The transceivers have a proprietary
low-dropout transmitter output stage enabling true RS-
232 performance from a +3.0V to +5.5V supply with a
dual charge pump. The charge pump requires only four
small 0.1µF capacitors for operation from a 3.3V supply.
The MAX3224–MAX3227 feature a logic-level output
(READY) that asserts when the charge pump is regulat-
ing and the device is ready to begin transmitting.
All devices are available in a space-saving TSSOP and
SSOP packages.
________________________Applications
Notebook, Subnotebook, and Palmtop Computers
Cellular Phones
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers
_Next Generation Device Features
♦For Smaller Packaging:
MAX3228/MAX3229: +2.5V to +5.5V RS-232
Transceivers in UCSP™
♦For Low-Voltage or Data Cable Applications:
MAX3380E/MAX3381E: +2.35V to +5.5V, 1µA,
2 Tx/2 Rx RS-232 Transceivers with ±15kV ESD-
Protected I/O and Logic Pins
♦For Integrated ESD Protection:
MAX3222E/MAX3232E/MAX3237E/MAX3241E†/
MAX3246E: ±15kV ESD-Protected, Down to 10nA,
+3.0V to +5.5V, Up to 1Mbps, True RS-232
Transceivers (MAX3246E Available in UCSP)
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
PART
MAX3224
MAX3225
MAX3226
1/1
2/2
2/2
NO. OF
DRIVERS/
RECEIVERS
READY
OUTPUT
✔
✔
✔
AUTO-
SHUTDOWN
PLUS
✔
✔
✔
250k
1M
250k
GUARANTEED
DATA RATE
(bps)
MAX3227
MAX3244
MAX3245
3/5
3/5
1/1 ✔
—
—
✔
✔
✔
1M
250k
1M
PART
MAX3224CPP
MAX3224CAP
MAX3224EPP -40°C to +85°C
0°C to +70°C
0°C to +70°C
TEMP RANGE PIN-PACKAGE
20 Plastic DIP
20 SSOP
20 Plastic DIP
MAX3224EAP
MAX3225CPP
MAX3225CAP 0°C to +70°C
0°C to +70°C
-40°C to +85°C 20 SSOP
20 Plastic DIP
20 SSOP
MAX3225EPP -40°C to +85°C 20 Plastic DIP
MAX3225EAP -40°C to +85°C 20 SSOP
Ordering Information continued at end of data sheet.
_____________________ Selector Guide
_______________Ordering Information
MAX3224CUP 0°C to +70°C 20 TSSOP
MAX3224EUP -40°C to +85°C 20 TSSOP
MAX3225CUP 0°C to +70°C 20 TSSOP
MAX3225EUP -40°C to +85°C 20 TSSOP
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= TMIN to TMAX,
unless otherwise noted. Typical values are at TA= +25°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.
VCC to GND..............................................................-0.3V to +6V
V+ to GND (Note 1)..................................................-0.3V to +7V
V- to GND (Note 1) ...................................................+0.3V to -7V
V+ +V-(Note 1) ................................................................+13V
Input Voltages
T_IN, FORCEON, FORCEOFF to GND................ -0.3V to +6V
R_IN to GND ....................................................................±25V
Output Voltages
T_OUT to GND.............................................................±13.2V
R_OUT, INVALID, READY to GND .........-0.3V to (VCC + 0.3V)
Short-Circuit Duration
T_OUT to GND .......................................................Continuous
Continuous Power Dissipation (TA= +70°C)
16-Pin SSOP (derate 7.14mW/°C above +70°C) .........571mW
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 (derate 7.00mW/°C above +70°C) .......559mW
28-Pin Wide SO (derate 12.5mW/°C above +70°C)........... 1W
28-Pin SSOP (derate 9.52mW/°C above +70°C) .........762mW
Operating Temperature Ranges
MAX32_ _C_ _....................................................0°C to +70°C
MAX32_ _E_ _..................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°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.
VCC = 5.0V
FORCEON = GND, FORCEOFF = VCC,
all R_IN idle, all T_IN idle
TA= +25°C
VCC = 3.3V
T_IN, FORCEON,
FORCEOFF
CONDITIONS
kΩ357Input Resistance
V0.5Input Hysteresis
1.8 2.4 V
1.5 2.4
Input Threshold High
0.8 1.5 V
0.6 1.2
Input Threshold Low
V-25 +25Input Voltage Range
V
VCC - 0.6 VCC - 0.1
Output Voltage High
V0.4Output Voltage Low
µA110Supply Current, Shutdown
µA110
Supply Current,
AutoShutdown Plus
µA±0.05 ±10Output Leakage Current
µA±0.01 ±1
Transmitter Input Hysteresis V0.5
V
2.4
Input Logic Threshold High
mA0.3 1
Supply Current,
AutoShutdown Plus Disabled
V0.8Input Logic Threshold Low
2
UNITSMIN TYP MAXSYMBOLPARAMETER
FORCEOFF = GND
TA= +25°C
VCC = 5.0V
VCC = 3.3V
TA= +25°C
R_OUT (MAX3244/MAX3245), receivers
disabled
T_IN, FORCEON, FORCEOFF
VCC = 5.0V
FORCEON = FORCEOFF = VCC, no load
T_IN, FORCEON, FORCEOFF
IOUT = -1.0mA
VCC = 3.3V
IOUT = 1.6mA
DC CHARACTERISTICS (VCC = 3.3V or 5.0V, TA= +25°C)
LOGIC INPUTS AND RECEIVER OUTPUTS
RECEIVER INPUTS
Input Leakage Current
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= TMIN to TMAX,
unless otherwise noted. Typical values are at TA= +25°C.)
CONDITIONS
Ω300 10MOutput Resistance
V±5 ±5.4Output Voltage Swing
UNITSMIN TYP MAXSYMBOLPARAMETER
Figure 4a
T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩto GND,
T1OUT and T2OUT loaded with
2.5mA each
sec15 30 60t
AUTOSHDN
Receiver or Transmitter Edge to
Transmitters Shutdown
µs100tWU
Receiver or Transmitter Edge to
Transmitters Enabled
µs30tINVL
Receiver Positive or Negative
Threshold to INVALID Low
µs1tINVH
Receiver Positive or Negative
Threshold to INVALID High
V
VCC - 0.6
INVALID, READY
(MAX3224–MAX3227)
Output Voltage High
V0.4
INVALID, READY
(MAX3224–MAX3227)
Output Voltage Low
V-0.3 0.3
Receiver Input Threshold to
INVALID Output Low
-2.7 V
2.7
Receiver Input Threshold to
INVALID Output High
V±5Transmitter Output Voltage
µA±25Output Leakage Current
±60 mAOutput Short-Circuit Current
VCC = V+ = V- = 0, transmitter outputs = ±2V
All transmitter outputs loaded with 3kΩto
ground
VCC = 5V, Figure 5b (Note 2)
VCC = 5V, Figure 5b (Note 2)
VCC = 5V, Figure 4b
VCC = 5V, Figure 4b
IOUT = -1.0mA
IOUT = -1.6mA
Figure 4a
Negative threshold
Positive threshold
VCC = 0 or 3V to 5.5V, VOUT = ±12V,
Transmitters disabled
TRANSMITTER OUTPUTS
MOUSE DRIVEABILITY (MAX3244/MAX3245)
AUTOSHUTDOWN PLUS (FORCEON = GND, FORCEOFF = VCC)
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
4_______________________________________________________________________________________
TIMING CHARACTERISTICS—MAX3224/MAX3226/MAX3244
(VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= TMIN to TMAX,
unless otherwise noted. Typical values are at TA= +25°C.)
TIMING CHARACTERISTICS—MAX3225/MAX3227/MAX3245
(VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= TMIN to TMAX,
unless otherwise noted. Typical values are at TA= +25°C.)
Note 2: A transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic thresholds.
Note 3: Transmitter skew is measured at the transmitter zero cross points.
CL= 150pF
to 2500pF
CL= 150pF
to 1000pF
R_IN to R_OUT, CL= 150pF
RL= 3kΩ, CL= 1000pF,
one transmitter switching
VCC = 3.3V, TA= +25°C,
RL= 3kΩto 7kΩ,
measured from +3V to -3V
or -3V to +3V
Normal operation (MAX3244 only)
Normal operation (MAX3244 only)
(Note 3)
CONDITIONS
0.15tPLH µs
0.15tPHL
kbps250Maximum Data Rate
Receiver Propagation Delay
V/µs
430
630
Transition-Region Slew Rate
ns200Receiver Output Enable Time
ns200Receiver Output Disable Time
ns100
tPHL - tPLH
Transmitter Skew
ns50
tPHL - tPLH
Receiver Skew
UNITSMIN TYP MAXSYMBOLPARAMETER
VCC = 4.5V to 5.5V, RL= 3kΩ,
CL= 1000pF, one transmitter switching
VCC = 3.0V to 4.5V, RL= 3kΩ,
CL= 250pF, one transmitter switching
RL= 3kΩ, CL= 1000pF,
one transmitter switching
VCC = 3.3V, TA= +25°C,
RL= 3kΩto 7kΩ, CL= 150pF to 1000pF,
measured from +3V to -3V or -3V to +3V
(Note 3)
R_IN to R_OUT, CL= 150pF
Normal operation (MAX3245 only)
Normal operation (MAX3245 only)
CONDITIONS
1000
1000 kbps
250
Maximum Data Rate
V/µs24 150Transition-Region Slew Rate
ns50
tPHL - tPLH
Receiver Skew
ns25
tPHL - tPLH
Transmitter Skew
µs
0.15tPHL
Receiver Propagation Delay 0.15tPLH
ns200Receiver Output Enable Time
ns200Receiver Output Disable Time
UNITSMIN TYP MAXSYMBOLPARAMETER
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
_______________________________________________________________________________________ 5
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
01000 2000 3000 4000 5000
MAX3224/MAX3226
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3224-01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
T1 TRANSMITTING AT 250kbps
T2 (MAX3224) TRANSMITTING AT 15.6kbps
VOUT+
VOUT-
0
2
4
6
8
10
12
14
16
01000 2000 3000 4000 5000
MAX3224/MAX3226
SLEW RATE vs. LOAD CAPACITANCE
MAX3224-02
LOAD CAPACITANCE (pF)
SLEW RATE (V/µs)
-SLEW
+SLEW
FOR DATA RATES UP TO 250kbps
0
5
10
15
20
25
30
35
40
45
020001000 3000 4000 5000
MAX3224/MAX3226
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3224-03
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
250kbps
120kbps
20kbps
T1 TRANSMITTING AT 250kbps
T2 (MAX3224) TRANSMITTING AT 15.6kbps
-7.5
0
-2.5
-5.0
2.5
5.0
7.5
01000500 1500 2000 2500
MAX3225/MAX3227
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3224-04
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
2Mbps
2Mbps
1.5Mbps
1.5Mbps
1Mbps
1Mbps
1 TRANSMITTER AT FULL DATA RATE
1 TRANSMITTER AT 1/16 DATA RATE
(MAX3225)
LOAD = 3kΩ + CL
0
15
10
5
20
25
30
35
40
45
50
01000500 1500 2000 2500 3000
MAX3225/MAX3227
TRANSMITTER SKEW vs.
LOAD CAPACITANCE
MAX3224-07
LOAD CAPACITANCE (pF)
TRANSMITTER SKEW (ns)
AVERAGE; 10 PARTS
1 TRANSMITTER AT 512kbps
1 TRANSMITTER AT 30kbps
(MAX3225)
LOAD = 3kΩ + CL
0
80
70
60
50
40
30
20
10
0 500 1000 1500 2000 2500
MAX3225/MAX3227
SLEW RATE vs. LOAD CAPACITANCE
MAX3224-05
LOAD CAPACITANCE (pF)
SLEW RATE (V/µs)
1 TRANSMITTER AT 1Mbps
1 TRANSMITTER AT 62.5kbps (MAX3225)
-SLEW
+SLEW
0
20
10
40
30
60
50
70
90
80
100
0500 1000 1500 2000 2500
MAX3225/MAX3227
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3224-06
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
2Mbps
1.5Mbps
1Mbps
1 TRANSMITTER AT FULL DATA RATE
1 TRANSMITTER AT 1/16 DATA RATE
(MAX3225)
LOAD = 3kΩ + CL
20
24
22
30
28
26
36
34
32
38
-40 0 20-20 40 60 80 100
MAX3224–MAX3227
READY TURN-ON TIME
vs. TEMPERATURE
MAX3224-08
TEMPERATURE (°C)
READY TURN-ON TIME (µs)
0
200
180
160
140
120
100
80
60
40
20
-40 0 20-20 40 6080100
MAX3224–MAX3227
READY TURN-OFF TIME
vs. TEMPERATURE
MAX3224-09
TEMPERATURE (°C)
READY TURN-OFF TIME (ns)
__________________________________________Typical Operating Characteristics
(VCC = +3.3V, 250kbps data rate, C1–C4 = 0.1µF, all transmitters loaded with 3kΩand CL, TA= +25°C, unless otherwise noted.)
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
6_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VCC = +3.3V, 250kbps data rate, C1–C4 = 0.1µF, all transmitters loaded with 3kΩand CL, TA= +25°C, unless otherwise noted.)
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
01000 2000 3000 4000 5000
MAX3244
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3224-10
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
1 TRANSMITTER AT 250kbps
2 TRANSMITTERS AT 15.6kbps
VOUT+
VOUT-
0
4
2
8
6
12
10
14
01000 2000 3000 4000 5000
MAX3244
SLEW RATE vs. LOAD CAPACITANCE
MAX3224-11
LOAD CAPACITANCE (pF)
SLEW RATE (V/µs)
0
30
20
10
40
50
60
020001000 3000 4000 5000
MAX3244
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3224-12
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
250kbps 120kbps
20kbps
1 TRANSMITTER AT 250kbps
2 TRANSMITTERS AT 15.6kbps
-7.5
0
-2.5
-5.0
2.5
5.0
7.5
0800400 1200 1600 2000
MAX3245
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3224-13
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
2Mbps
2Mbps
1.5Mbps
1.5Mbps
1Mbps
1Mbps
1 TRANSMITTER AT FULL DATA RATE
2 TRANSMITTERS AT 1/16 DATA RATE
0
20
10
40
30
60
50
70
90
80
100
0400 800 1200 1600 2000
MAX3245
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3224-15
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
2Mbps
1.5Mbps
1Mbps
1 TRANSMITTER AT FULL DATA RATE
2 TRANSMITTERS AT 1/16 DATA RATE
0
20
10
40
30
60
50
70
0400 800 1200 1600 2000
MAX3245
SLEW RATE vs. LOAD CAPACITANCE
MAX3224-14
LOAD CAPACITANCE (pF)
SLEW RATE (V/µs)
1 TRANSMITTER AT 1Mbps
2 TRANSMITTERS AT 62.5kbps
0
15
10
5
20
25
30
35
40
45
50
01000 2000 3000
MAX3245
TRANSMITTER SKEW vs.
LOAD CAPACITANCE
MAX3224-16
LOAD CAPACITANCE (pF)
TRANSMITTER SKEW (ns)
_______________Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3224–MAX3227/MAX3244/MAX3245’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), over
the +3.0V to +5.5V range. The charge pump operates
in discontinuous mode: if the output voltages are less
than 5.5V, the charge pump is enabled; if the output
voltages exceed 5.5V, the charge-pump is disabled.
Each charge pump requires a flying capacitor (C1, C2)
and a reservoir capacitor (C3, C4) to generate the V+
and V- supplies.
The READY output (MAX3224–MAX3227) is low when
the charge pumps are disabled in shutdown mode. The
READY signal asserts high when V- goes below -4V.
RS-232 Transmitters
The transmitters are inverting level translators that
convert CMOS-logic levels to 5.0V EIA/TIA-232 levels.
The MAX3224/MAX3226/MAX3244 guarantee a
250kbps data rate (1Mbps for the MAX3225/MAX3227/
MAX3245) with worst-case loads of 3kΩin parallel with
1000pF, providing compatibility with PC-to-PC com-
munication software (such as LapLink™). Transmitters
can be paralleled to drive multiple receivers. Figure 1
shows a complete system connection.
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
_______________________________________________________________________________________ 7
PIN
NAME
MAX3224
MAX3225
MAX3226
MAX3227
MAX3244
MAX3245
1 1 — READY
2 2 28 C1+ Positive Terminal of Voltage-Doubler Charge-Pump Capacitor
3 3 27 V+ +5.5V generated by the charge pump
4 4 24 C1- Negative Terminal of Voltage-Doubler Charge-Pump Capacitor
5 5 1 C2+ Positive Terminal of Inverting Charge-Pump Capacitor
6 6 2 C2- Negative Terminal of Inverting Charge-Pump Capacitor
7 7 3 V- -5.5V generated by the charge pump
8, 17 13 9–11 T_OUT RS-232 Transmitter Outputs
9, 16 84–8 R_IN RS-232 Receiver Inputs
10, 15 9 15–19 R_OUT TTL/CMOS Receiver Outputs
11 10 21 INVALID Valid Signal Detector Output, active low. A logic high indicates that a valid
RS-232 level is present on a receiver input.
12, 13 11 12–14 T_IN TTL/CMOS Transmitter Inputs
14 12 23 FORCEON Force-On Input, active high. Drive high to override AutoShutdown Plus,
keeping transmitters and receivers on (FORCEOFF must be high) (Table 1).
18 14 25 GND Ground
19 15 26 VCC +3.0V to +5.5V Single Supply Voltage
20 16 22 FORCEOFF
Force-Off Input, active low. Drive low to shut down transmitters, receivers
(except R2OUTB), and charge pump. This overrides AutoShutdown Plus
and FORCEON (Table 1).
— — 20 R2OUTB TTL/CMOS Noninverting Complementary Receiver Outputs. Always active.
Ready to Transmit Output, active high. READY is enabled high when
V- goes below -4V and the device is ready to transmit.
FUNCTION
Pin Description
LapLink is a trademark of Traveling Software.
MAX3224–MAX3227/MAX3244/MAX3245†
When FORCEOFF is driven to ground or when the Auto-
Shutdown Plus circuitry senses that all receiver and
transmitter inputs are inactive for more than 30sec, the
transmitters are disabled and the outputs go into a high-
impedance state. When powered off or shut down, the
outputs can be driven to ±12V. The transmitter inputs
do not have pull-up resistors. Connect unused inputs to
GND or VCC.
RS-232 Receivers
The receivers convert RS-232 signals to CMOS-logic
output levels. The MAX3224–MAX3227 feature inverting
outputs that always remain active (Table 1). The
MAX3244/MAX3245 have inverting three-state outputs
that are high impedance when shut down (FORCEOFF
= GND) (Table 1).
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
8_______________________________________________________________________________________
Figure 1. Interface Under Control of PMU
Figure 2. The MAX3244/MAX3245 detect RS-232 activity when
the UART and interface are shut down.
The MAX3244/MAX3245 feature an extra, always
active, noninverting output, R2OUTB. R2OUTB output
monitors receiver activity while the other receivers are
high impedance, allowing Ring Indicator applications to
be monitored without forward biasing other devices
connected to the receiver outputs. This is ideal for sys-
tems where VCC is set to ground in shutdown to
accommodate peripherals such as UARTs (Figure 2).
The MAX3224–MAX3227/MAX3244/MAX3245 feature
an INVALID output that is enabled low when no valid
RS-232 voltage levels have been detected on all
receiver inputs. Because INVALID indicates the receiv-
er input’s condition, it is independent of FORCEON and
FORCEOFF states (Figures 3 and 4).
AutoShutdown Plus Mode
The MAX3224–MAX3227/MAX3244/MAX3245 achieve a
1µA supply current with Maxim’s AutoShutdown
Plusfeature, which operates when FORCEOFF is high
and a FORCEON is low. When these devices do not
sense a valid signal transition on any receiver and trans-
mitter input for 30sec, the on-board charge pumps are
shut down, reducing supply current to 1µA. This occurs
if the RS-232 cable is disconnected or if the connected
peripheral transmitters are turned off, and the UART dri-
ving the transmitter inputs is inactive. The system turns
on again when a valid transition is applied to any
RS-232 receiver or transmitter input. As a result, the sys-
tem saves power without changes to the existing BIOS
or operating system.
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
_______________________________________________________________________________________ 9
Table 1. Output Control Truth Table
OPERATION
STATUS FORCEON FORCEOFF
VALID
RECEIVER
LEVEL
RECEIVER OR
TRANSMITTER
EDGE WITHIN
30sec
T_OUT
R_OUT
(MAX3224/
MAX3225/
MAX3226/
MAX3227)
R_OUT
(MAX3244/
MAX3245)
R2OUTB
(MAX3244/
MAX3245)
Shutdown
(Forced Off) X 0 X X High-Z Active High-Z Active
Normal
Operation
(Forced On)
1 1 X X Active Active Active Active
Normal
Operation
(AutoShutdown
Plus)
0 1 X Yes Active Active Active Active
Shutdown (Auto-
Shutdown Plus) 0 1 X No High-Z Active Active Active
Normal
Operation INVALID*1Yes XActive Active Active Active
Normal
Operation INVALID*1 X Yes Active Active Active Active
Shutdown INVALID*1No No High-Z Active Active Active
Normal
Operation
(AutoShutdown) INVALID*INVALID** Yes XActive Active Active Active
Shutdown
(AutoShutdown) INVALID*INVALID** No XHigh-Z Active High-Z Active
X = Don’t care
*
INVALID
connected to FORCEON
**
INVALID
connected to FORCEON and
FORCEOFF
MAX3224–MAX3227/MAX3244/MAX3245†
Figures 3a and 3b depict valid and invalid RS-232
receiver voltage levels. INVALID indicates the receiver
input’s condition, and is independent of FORCEON and
FORCEOFF states. Figure 3 and Tables 1 and 2 sum-
marize the operating modes of the MAX3224–
MAX3227/MAX3244/MAX3245 devices. FORCEON and
FORCEOFF override AutoShutdown Plus circuitry.
When neither control is asserted, the IC selects
between these states automatically based on the last
receiver or transmitter input edge received.
When shut down, the device’s charge pumps turn off,
V+ is pulled to VCC, V- is pulled to ground, the transmit-
ter outputs are high impedance, and READY
(MAX3224–MAX3227) is driven low. The time required
to exit shutdown is typically 100µs (Figure 8).
By connecting FORCEON to INVALID, the MAX3224–
MAX3227/MAX3244/MAX3245 shut down when no valid
receiver level and no receiver or transmitter edge is
detected for 30sec, and wake up when a valid receiver
level or receiver or transmitter edge is detected.
By connecting FORCEON and FORCEOFF to INVALID,
the MAX3224–MAX3227/MAX3244/MAX3245 shutdown
when no valid receiver level is detected and wake up
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
10 ______________________________________________________________________________________
+2.7V
-2.7V
INVALID
R_IN
INVALID DEASSERTED IF ANY RECEIVER INPUT HAS BEEN BETWEEN +2.7V AND -2.7V
FOR LESS THAN 30µs.
30µs
TIMER
R
AUTOSHDN
R_IN
T_IN
R
S
30sec
TIMER
EDGE
DETECT
EDGE
DETECT
FORCEOFF
FORCEON
Figure 3a.
INVALID
Functional Diagram,
INVALID
Low
Figure 3b.
INVALID
Functional Diagram,
INVALID
High
Figure 3c. AutoShutdown Plus Logic
Figure 3d. Power-Down Logic
Figure 4a. Receiver Positive/Negative Thresholds for
INVALID
RS-232 SIGNAL
PRESENT AT ANY
RECEIVER INPUT
INVALID OUTPUT
Yes High
No Low
Table 2. INVALID Truth Table
when a valid receiver level is detected (same function-
ality as AutoShutdown feature on MAX3221/MAX3223/
MAX3243).
A mouse or other system with AutoShutdown Plus may
need time to wake up. Figure 5 shows a circuit that
forces the transmitters on for 100ms, allowing enough
time for the other system to realize that the MAX3244/
MAX3245 is awake. If the other system outputs valid
RS-232 signal transitions within that time, the RS-232
ports on both systems remain enabled.
Software-Controlled Shutdown
If direct software control is desired, use INVALID to
indicate DTR or Ring Indicator signal. Tie FORCEOFF
and FORCEON together to bypass the AutoShutdown
Plus so the line acts like a SHDN input.
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
______________________________________________________________________________________ 11
VCC
0
0
V+
V-
VCC
0
INVALID
OUTPUT
OUTPUT
TRANSMITTER
INPUTS
RECEIVER
INPUTS }INVALID
REGION
*MAX3224–MAX3227
TRANSMITTER
OUTPUTS
*VCC
tAUTOSHDN tWU tWU
tINVL tINVH tAUTOSHDN
Figure 4b. AutoShutdown Plus,
INVALID,
and READY Timing Diagram
Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a
Mouse or Another System
Table 3. Required Minimum Capacitance
Values
MAX3224–MAX3227/MAX3244/MAX3245†
__________Applications Information
Capacitor Selection
The capacitor type used for C1–C4 is not critical for
proper operation; polarized or nonpolarized capacitors
can be used. The charge pump requires 0.1µF capaci-
tors for 3.3V operation. For other supply voltages, see
Table 3 for required capacitor values. Do not use val-
ues 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, C4,
and CBYPASS, 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 capaci-
tors with a larger nominal value. The capacitor’s equiv-
alent series resistance (ESR), which usually rises at low
temperatures, influences the amount of ripple on V+
and V-.
Power-Supply Decoupling
In most circumstances, a 0.1µF VCC bypass capacitor
is adequate. In applications that are sensitive to power-
supply noise, use a capacitor of the same value as
charge-pump capacitor C1. Connect bypass capaci-
tors 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 trans-
mitter outputs are shown going to opposite RS-232 lev-
els (one transmitter input is high; the other is low). Each
transmitter is loaded with 3kΩin parallel with 1000pF.
The transmitter outputs display no ringing or undesir-
able transients as they come out of shutdown. Note that
the transmitters are enabled only when the magnitude
of V- exceeds approximately -3V.
High Data Rates
The MAX3224/MAX3226/MAX3244 maintain the RS-232
±5.0V minimum transmitter output voltage even at high
data rates. Figure 7 shows a transmitter loopback test
circuit. Figure 8 shows a loopback test result at
120kbps, and Figure 9 shows the same test at
250kbps. For Figure 8, all transmitters were driven
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
12 ______________________________________________________________________________________
VCC
(V)
C2, C3, C4
(µF)
3.0 to 3.6 0.1
C1, CBYPASS
(µF)
0.1
4.5 to 5.5 0.33
3.0 to 5.5 1
0.047
0.22
5µs/div
T1OUT
FORCEON =
FORCEOFF
T2OUT
READY
5V/div
0
2V/div
0
5V/div
0
VCC = 3.3V
C1–C4 = 0.1µF
Figure 6. Transmitter Outputs when Exiting Shutdown or
Powering Up
Figure 7. Loopback Test Circuit
simultaneously at 120kbps into RS-232 loads in parallel
with 1000pF. For Figure 9, a single transmitter was dri-
ven at 250kbps, and all transmitters were loaded with
an RS-232 receiver in parallel with 250pF.
The MAX3225/MAX3227/MAX3245 maintain the RS-232
±5.0V minimum transmitter output voltage at data rates
up to 1Mbps (MegaBaud). Figure 10 shows a loopback
test result with a single transmitter driven at 1Mbps and
all transmitters loaded with an RS-232 receiver in paral-
lel with 250pF.
Mouse Driveability
The MAX3244/MAX3245 are specifically designed to
power serial mice while operating from low-voltage
power supplies. They have been tested with leading
mouse brands from manufacturers such as Microsoft
and Logitech. The MAX3244/MAX3245 successfully
drove all serial mice tested and met their respective
current and voltage requirements. The MAX3244/
MAX3245 dual charge pump ensures the transmitters
will supply at least ±5V during worst-case conditions.
Figure 11a shows the transmitter output voltages under
increasing load current. Figure 11b shows a typical
mouse connection.
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
______________________________________________________________________________________ 13
Figure 8. MAX3224/MAX3226/MAX3244 Loopback Test Result
at 120kbps
Figure 9. MAX3224/MAX3226/MAX3244 Loopback Test Result
at 250kbps
Figure 10. MAX3225/MAX3227/MAX3245 Loopback Test
Result at 1Mbps
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
012345678910
LOAD CURRENT PER TRANSMITTER (mA)
TRANSMITTER OUTPUT VOLTAGE (V)
VOUT+
VOUT-
VOUT+
VOUT-
VCC
VCC = 3.0V
Figure 11a. MAX324_ Transmitter Output Voltage vs. Load
Current per Transmitter
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
14 ______________________________________________________________________________________
Figure 11b. Mouse Driver Test Circuit
+V
COMPUTER SERIAL PORT
+V
-V
GND
Tx
SERIAL
MOUSE
MAX3244
MAX3245
FORCEOFF
23
R5OUT
15
R4OUT
16
R3OUT
17
R2OUT
18
R1OUT
19
R2OUTB
20
LOGIC
OUTPUTS
5k
5k
5k
5k
5k
R5IN 8
R4IN 7
R3IN 6
R2IN 5
R1IN 4
RS-232
INPUTS
GND
25
LOGIC
INPUTS
T3IN
12
T2IN
13
T1IN
14
C2-
2
C2+
1
C1-
24
C1+
28
T3OUT 11
T2OUT 10
T1OUT 9
V- 3
V+ 27
VCC
VCC
C4
0.1µF
C3
0.1µF
0.1µF 26
C1
0.1µF
C2
0.1µF
FORCEON
INVALID
22
21
TO POWER-
MANAGEMENT
UNIT
+3.3V
Interconnection with 3V and 5V Logic
The MAX3224–MAX3227/MAX3244/MAX3245 can
directly interface with various 5V logic families, includ-
ing ACT and HCT CMOS. See Table 4 for more infor-
mation on possible combinations of interconnections.
Table 5 lists other Maxim 3.0V to 5.5V powered trans-
ceivers.
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
______________________________________________________________________________________ 15
Table 4. Logic Family Compatibility with Various Supply Voltages
SYSTEM
POWER-SUPPLY
VOLTAGE (V)
COMPATIBILITY
3.3 Compatible with all CMOS families
5Compatible with all TTL and CMOS families
VCC SUPPLY
VOLTAGE
(V)
3.3
5
5Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS3.3
Table 5. 3.0V to 5.5V Powered RS-232 Transceivers from Maxim
PART
SUPPLY
VOLTAGE
RANGE
(V)
NO.
OF
Tx/Rx
GUARANTEED
DATA RATE
(bps)
SUPPLY
CURRENT
(µA)
MAX3241 +3.0 to +5.5 3/5 120k300
MAX3243 +3.0 to +5.5 3/5 120k1
MAX3244 +3.0 to +5.5 3/5 250k1
MAX3245 +3.0 to +5.5 3/5 1M1
MAX3232 +3.0 to +5.5 2/2 120k300
MAX3222 +3.0 to +5.5 2/2 120k300
MAX3223 +3.0 to +5.5 2/2 120k1
MAX3224 +3.0 to +5.5 2/2 250k1
MAX3225 +3.0 to +5.5 2/2 1M1
MAX3221 +3.0 to +5.5 1/1 120k1
MAX3227 +3.0 to +5.5 1/1 1M1
MAX3226 +3.0 to +5.5 1/1 250k1
AUTO-
SHUTDOWN
PLUS
—
—
Yes
Yes
—
—
—
Yes
Yes
—
Yes
Yes
AUTO-
SHUTDOWN
—
Yes
—
—
—
—
Yes
—
—
Yes
—
—
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
16 ______________________________________________________________________________________
MAX3244
MAX3245
FORCEON
23
R5OUT
15
R4OUT
16
R3OUT
17
R2OUT
18
R1OUT
19
R2OUTB
20
FORCEOFF
22
R5IN 8
R4IN 7
R3IN 6
R2IN 5
R1IN 4
GND
25
T3IN
12
T2IN
13
T1IN
14
C2-
2
C2+
1
C1-
24
C1+
28
T3OUT 11
T2OUT 10
T1OUT 9
V- 3
V+ 27
VCC
C4
0.1µF
C3
0.1µF
C1
0.1µF
CBYPASS
0.1µF
C2
0.1µF
+3.3V
26
INVALID 21
AUTOSHUTDOWN
PLUS
MAX3226
MAX3227
FORCEON
READY
12
1
R1OUT9
FORCEOFF 16
INVALID 10
GND
14
T1IN
11
C2-
6
C2+
5
C1-
4
C1+
2
R1IN 8
T1OUT 13
V- 7
V+ 3
VCC
VCC
C4
0.1µF
C3
0.1µF
0.1µF 15
C1
0.1µF
C2
0.1µF
CBYPASS
CBYPASS
+3.3V
TO POWER-
MANAGEMENT
UNIT
5k
MAX3224
MAX3225
FORCEON
READY
14
1
R2OUT10
R1OUT15
FORCEOFF 20
INVALID 11
R2IN 9
GND
18
RS-232
OUTPUTS
TTL/CMOS
INPUTS T2IN
12
T1IN
13
C2-
6
C2+
5
C1-
4
C1+
2
R1IN 16
T2OUT 8
T1OUT 17
V- 7
V+ 3
VCC
VCC
C4
0.1µF
C3
0.1µF
0.1µF 19
C1
0.1µF
C2
0.1µF
+3.3V
RS-232
INPUTS
TO POWER-
MANAGEMENT
UNIT
TTL/CMOS
OUTPUTS 5k
5k
5k
5k
5k
5k
5k
AUTOSHUTDOWN
PLUS
AUTOSHUTDOWN
PLUS
___________________________________________________Typical Operating Circuits
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
______________________________________________________________________________________ 17
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
READY
C1+
V+
C1-
C2+
C2-
V-
R1IN
FORCEOFF
VCC
GND
T1OUT
FORCEON
T1IN
INVALID
R1OUT
MAX3226
MAX3227
SSOP
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
C1+
V+
VCC
GND
C1-
FORCEON
FORCEOFF
INVALID
R2OUTB
R1OUT
R2OUT
R3OUT
R4OUT
R5OUT
C2+
C2-
V-
R1IN
R2IN
R3IN
R4IN
R5IN
T1OUT
T2OUT
T3OUT
T3IN
T2IN
T1IN
SO/SSOP
MAX3244
MAX3245
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
FORCEOFF
VCC
GND
T1OUT
C1-
V+
C1+
READY
R1IN
R1OUT
FORCEON
T1IN
T2OUT
V-
C2-
C2+
12
11
9
10
T2IN
INVALIDR2OUT
R2IN
DIP/SSOP/TSSOP
MAX3224
MAX3225
___________________________________________________________Pin Configurations
___________________Chip Information
MAX3224 TRANSISTOR COUNT: 1129
MAX3225 TRANSISTOR COUNT: 1129
MAX3226 TRANSISTOR COUNT: 1129
MAX3227 TRANSISTOR COUNT: 1129
MAX3244/MAX3245 TRANSISTOR COUNT: 1335
__Ordering Information (continued)
PART
MAX3227CAE
MAX3227EAE -40°C to +85°C
0°C to +70°C 16 SSOP
16 SSOP
TEMP RANGE PIN-PACKAGE
MAX3226CAE
MAX3226EAE
MAX3244CWI 0°C to +70°C
-40°C to +85°C
0°C to +70°C 16 SSOP
16 SSOP
28 Wide SO
MAX3244CAI
MAX3244EWI
MAX3244EAI -40°C to +85°C
-40°C to +85°C
0°C to +70°C 28 SSOP
28 Wide SO
28 SSOP
MAX3245CWI 0°C to +70°C 28 Wide SO
MAX3245CAI
MAX3245EWI
MAX3245EAI -40°C to +85°C
-40°C to +85°C
0°C to +70°C 28 SSOP
28 Wide SO
28 SSOP
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
18 ______________________________________________________________________________________
SSOP.EPS
PACKAGE OUTLINE, SSOP, 5.3 MM
1
1
21-0056 C
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
NOTES:
1. D&E DO NOT INCLUDE MOLD FLASH.
2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").
3. CONTROLLING DIMENSION: MILLIMETERS.
4. MEETS JEDEC MO150.
5. LEADS TO BE COPLANAR WITHIN 0.10 MM.
7.90
H
L
0∞
0.301
0.025
8∞
0.311
0.037
0∞
7.65
0.63
8∞
0.95
MAX
5.38
MILLIMETERS
B
C
D
E
e
A1
DIM
A
SEE VARIATIONS
0.0256 BSC
0.010
0.004
0.205
0.002
0.015
0.008
0.212
0.008
INCHES
MIN MAX
0.078
0.65 BSC
0.25
0.09
5.20
0.05
0.38
0.20
0.21
MIN
1.73 1.99
MILLIMETERS
6.07
6.07
10.07
8.07
7.07
INCHES
D
D
D
D
D
0.239
0.239
0.397
0.317
0.278
MIN
0.249
0.249
0.407
0.328
0.289
MAX MIN
6.33
6.33
10.33
8.33
7.33
14L
16L
28L
24L
20L
MAX N
A
D
eA1 L
C
HE
N
12
B
0.068
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
______________________________________________________________________________________ 19
SOICW.EPS
PACKAGE OUTLINE, .300" SOIC
1
1
21-0042 B
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
TOP VIEW
FRONT VIEW
MAX
0.012
0.104
0.019
0.299
0.013
INCHES
0.291
0.009
E
C
DIM
0.014
0.004
B
A1
MIN
0.093A
0.23
7.40 7.60
0.32
MILLIMETERS
0.10
0.35
2.35
MIN
0.49
0.30
MAX
2.65
0.050
0.016L0.40 1.27
0.5120.496D
D
MINDIM
D
INCHES
MAX
12.60 13.00
MILLIMETERS
MIN MAX
20 AC
0.447 0.463 AB11.7511.35 18
0.398 0.413 AA10.5010.10 16
NMS013
SIDE VIEW
H0.4190.394 10.00 10.65
e0.050 1.27
D0.6140.598 15.20 2415.60 AD
D0.7130.697 17.70 2818.10 AE
H
E
N
D
A1
B
e
A
0∞-8∞
C
L
1
VARIATIONS:
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX3224–MAX3227/MAX3244/MAX3245†
1µA Supply Current, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
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.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
©2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
PDIPN.EPS
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)