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19-1289; Rev 4; 10/08
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
________________General Description
The MAX3224-MAX3227/MAX3244/MAX3245 are 3Vpowered EIA/TIA-232 and V.28/V.24 communications interfaces with automatic shutdown/wakeup features and high data-rate capabilities. All devices achieve a 1A supply current using Maxim's revolutionary AutoShutdown PlusTM 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 receiver input. AutoShutdown Plus saves power without changes to the existing BIOS or operating system. The MAX3225/MAX3227/MAX3245 also feature MegaBaudTM operation, guaranteeing 1Mbps for highspeed 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 RS232 performance from a +3.0V to +5.5V supply with a dual charge pump. The charge pump requires only four small 0.1F capacitors for operation from a 3.3V supply. The MAX3224-MAX3227 feature a logic-level output (READY) that asserts when the charge pump is regulating and the device is ready to begin transmitting. All devices are available in a space-saving TQFN, TSSOP, and SSOP packages.
_Next Generation Device Features
For Smaller Packaging: MAX3228/MAX3229: +2.5V to +5.5V RS-232 Transceivers in UCSPTM For Low-Voltage or Data Cable Applications: MAX3380E/MAX3381E: +2.35V to +5.5V, 1A, 2 Tx/2 Rx RS-232 Transceivers with 15kV ESDProtected 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
_______________Ordering Information
PART MAX3224CPP MAX3224CAP MAX3224CTP MAX3224CUP MAX3224EPP MAX3224EAP MAX3224ETP MAX3224EUP TEMP RANGE 0C to +70C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 20 Plastic DIP 20 SSOP 20 Thin QFN-EP* 20 TSSOP 20 Plastic DIP 20 SSOP 20 Thin QFN-EP* 5mm x 5mm 20 TSSOP
________________________Applications
Notebook, Subnotebook, and Palmtop Computers Cellular Phones Battery-Powered Equipment Handheld Equipment
Ordering Information continued at end of data sheet.
*EP = Exposed paddle.
_____________________ Selector Guide
PART NO. OF GUARANTEED AUTOREADY DRIVERS/ DATA RATE SHUTDOWN OUTPUT RECEIVERS PLUS (bps) 2/2 2/2 1/1 1/1 3/5 3/5 250k 1M 250k 1M 250k 1M -- --
Peripherals Printers
MAX3224 MAX3225 MAX3226 MAX3227 MAX3244 MAX3245
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.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
ABSOLUTE MAXIMUM RATINGS
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 = +70C) 16-Pin SSOP (derate 7.14mW/C above +70C) .........571mW 20-Pin Plastic DIP (derate 11.11mW/C above +70C) ...889mW 20-Pin TQFN (derate 21.3mW/C above +70C)........1702.1mW 20-Pin SSOP (derate 8.00mW/C above +70C) .........640mW 20-Pin TSSOP (derate 7.00mW/C above +70C) .......559mW 28-Pin Wide SO (derate 12.5mW/C above +70C)........... 1W 28-Pin SSOP (derate 9.52mW/C above +70C) .........762mW Operating Temperature Ranges MAX32_ _C_ _....................................................0C to +70C MAX32_ _E_ _ ..................................................-40C to +85C Storage Temperature Range .............................-65C to +160C Lead Temperature (soldering, 10s) .................................+300C
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 = +3V to +5.5V, C1-C4 = 0.1F, tested at 3.3V 10%; CL = 0.047F, C2-C4 = 0.33F, tested at 5.0V 10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Supply Current, AutoShutdown Plus Supply Current, Shutdown Supply Current, AutoShutdown Plus Disabled LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low Input Logic Threshold High Transmitter Input Hysteresis Input Leakage Current Output Leakage Current Output Voltage Low Output Voltage High RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance 2 TA = +25C 3 TA = +25C TA = +25C VCC = 3.3V VCC = 5.0V VCC = 3.3V VCC = 5.0V -25 0.6 0.8 1.2 1.5 1.5 1.8 0.5 5 7 2.4 2.4 +25 V V V V k T_IN, FORCEON, FORCEOFF R_OUT (MAX3244/MAX3245), receivers disabled IOUT = 1.6mA IOUT = -1.0mA VCC - 0.6 VCC - 0.1 T_IN, FORCEON, FORCEOFF T_IN, FORCEON, FORCEOFF VCC = 3.3V VCC = 5.0V 2 2.4 0.5 0.01 0.05 1 10 0.4 0.8 V V V A A V V SYMBOL CONDITIONS FORCEON = GND, FORCEOFF = VCC, all R_IN idle, all T_IN idle FORCEOFF = GND FORCEON = FORCEOFF = VCC, no load MIN TYP MAX UNITS DC CHARACTERISTICS (VCC = 3.3V or 5.0V, TA = +25C) 1 1 0.3 10 10 1 A A mA
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3V to +5.5V, C1-C4 = 0.1F, tested at 3.3V 10%; CL = 0.047F, C2-C4 = 0.33F, tested at 5.0V 10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current VCC = 0 or 3V to 5.5V, VOUT = 12V, Transmitters disabled All transmitter outputs loaded with 3k to ground VCC = V+ = V- = 0, transmitter outputs = 2V 5 300 5.4 10M 60 25 V mA A SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX3224-MAX3227/MAX3244/MAX3245
MOUSE DRIVEABILITY (MAX3244/MAX3245) T1IN = T2IN = GND, T3IN = VCC, T3OUT loaded with 3k to GND, Transmitter Output Voltage T1OUT and T2OUT loaded with 2.5mA each AUTOSHUTDOWN PLUS (FORCEON = GND, FORCEOFF = VCC) Receiver Input Threshold to INVALID Output High Receiver Input Threshold to INVALID Output Low INVALID, READY (MAX3224-MAX3227) Output Voltage Low INVALID, READY (MAX3224-MAX3227) Output Voltage High Receiver Positive or Negative Threshold to INVALID High Receiver Positive or Negative Threshold to INVALID Low Receiver or Transmitter Edge to Transmitters Enabled tINVH tINVL tWU Figure 4a Figure 4a Positive threshold Negative threshold -2.7 -0.3 0.3
5
V
2.7
V V
IOUT = -1.6mA
0.4
V
IOUT = -1.0mA
VCC - 0.6
V
VCC = 5V, Figure 4b VCC = 5V, Figure 4b VCC = 5V, Figure 5b (Note 2) 15
1 30 100 30 60
s s s s
Receiver or Transmitter Edge to tAUTOSHDN VCC = 5V, Figure 5b (Note 2) Transmitters Shutdown
_______________________________________________________________________________________
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
TIMING CHARACTERISTICS--MAX3224/MAX3226/MAX3244
(VCC = +3V to +5.5V, C1-C4 = 0.1F, tested at 3.3V 10%; CL = 0.047F, C2-C4 = 0.33F, tested at 5.0V 10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Maximum Data Rate Receiver Propagation Delay Receiver Output Enable Time Receiver Output Disable Time Transmitter Skew Receiver Skew tPHL - tPLH tPHL - tPLH tPHL tPLH SYMBOL CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching R_IN to R_OUT, CL = 150pF Normal operation (MAX3244 only) Normal operation (MAX3244 only) (Note 3) CL = 150pF to 1000pF CL = 150pF to 2500pF MIN 250 0.15 0.15 200 200 100 50 VCC = 3.3V, TA = +25C, RL = 3k to 7k, measured from +3V to -3V or -3V to +3V 6 4 30 V/s 30 TYP MAX UNITS kbps s ns ns ns ns
Transition-Region Slew Rate
TIMING CHARACTERISTICS--MAX3225/MAX3227/MAX3245
(VCC = +3V to +5.5V, C1-C4 = 0.1F, tested at 3.3V 10%; CL = 0.047F, C2-C4 = 0.33F, tested at 5.0V 10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching Maximum Data Rate VCC = 3.0V to 4.5V, RL = 3k, CL = 250pF, one transmitter switching VCC = 4.5V to 5.5V, RL = 3k, CL = 1000pF, one transmitter switching Receiver Propagation Delay Receiver Output Enable Time Receiver Output Disable Time Transmitter Skew Receiver Skew Transition-Region Slew Rate tPHL - tPLH tPHL - tPLH tPHL tPLH R_IN to R_OUT, CL = 150pF Normal operation (MAX3245 only) Normal operation (MAX3245 only) (Note 3) VCC = 3.3V, TA = +25C, RL = 3k to 7k, CL = 150pF to 1000pF, measured from +3V to -3V or -3V to +3V MIN 250 1000 1000 0.15 0.15 200 200 25 50 24 150 s ns ns ns ns V/s kbps TYP MAX UNITS
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.
4
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
__________________________________________Typical Operating Characteristics
(VCC = +3.3V, 250kbps data rate, C1-C4 = 0.1F, all transmitters loaded with 3k and CL, TA = +25C, unless otherwise noted.)
MAX3224/MAX3226 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE (V) 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0 1000 2000 3000
MAX3224-01
MAX3224-MAX3227/MAX3244/MAX3245
MAX3224/MAX3226 SLEW RATE vs. LOAD CAPACITANCE
MAX3224-02
MAX3224/MAX3226 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
40 SUPPLY CURRENT (mA) 35 30 25 20 15 10 20kbps 250kbps 120kbps
MAX3224-03
16 14 12 SLEW RATE (V/s) 10 8 6 4 +SLEW -SLEW
45
VOUT+ T1 TRANSMITTING AT 250kbps T2 (MAX3224) TRANSMITTING AT 15.6kbps
VOUT4000 5000
2 FOR DATA RATES UP TO 250kbps 0 0 1000 2000 3000 4000 5000
5 0 0
T1 TRANSMITTING AT 250kbps T2 (MAX3224) TRANSMITTING AT 15.6kbps 1000 2000 3000 4000 5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3225/MAX3227 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3224-04
MAX3225/MAX3227 SLEW RATE vs. LOAD CAPACITANCE
MAX3224-05
MAX3225/MAX3227 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
90 80 SUPPLY CURRENT (mA) 70 60 50 40 30 20 1Mbps 1 TRANSMITTER AT FULL DATA RATE 1 TRANSMITTER AT 1/16 DATA RATE (MAX3225) LOAD = 3k + CL 2Mbps 1.5Mbps
MAX3224-06
7.5 TRANSMITTER OUTPUT VOLTAGE (V) 5.0 2Mbps 2.5 0 -2.5 -5.0 -7.5 0 500 1000 1500 2000 1.5Mbps 1Mbps
80 70 60 SLEW RATE (V/s) -SLEW 50 +SLEW 40 30 20 10 0 1 TRANSMITTER AT 1Mbps 1 TRANSMITTER AT 62.5kbps (MAX3225) 0 500 1000 1500 2000
100
1 TRANSMITTER AT FULL DATA RATE 1 TRANSMITTER AT 1/16 DATA RATE (MAX3225) LOAD = 3k + CL 1.5Mbps 1Mbps 2Mbps
10 0 2500 0 500 1000 1500 2000 2500
2500
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3225/MAX3227 TRANSMITTER SKEW vs. LOAD CAPACITANCE
MAX3224-07
MAX3224-MAX3227 READY TURN-ON TIME vs. TEMPERATURE
MAX3224-08
MAX3224-MAX3227 READY TURN-OFF TIME vs. TEMPERATURE
180 READY TURN-OFF TIME (ns) 160 140 120 100 80 60 40 20 0
MAX3224-09
50 45 40 TRANSMITTER SKEW (ns) 35 30 25 20 15 10 5 0 0 500 1000 1500 2000 2500 AVERAGE; 10 PARTS 1 TRANSMITTER AT 512kbps 1 TRANSMITTER AT 30kbps (MAX3225) LOAD = 3k + CL
38 36 READY TURN-ON TIME (s) 34 32 30 28 26 24 22 20
200
3000
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
LOAD CAPACITANCE (pF)
TEMPERATURE (C)
TEMPERATURE (C)
_______________________________________________________________________________________
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
Typical Operating Characteristics (continued)
(VCC = +3.3V, 250kbps data rate, C1-C4 = 0.1F, all transmitters loaded with 3k and CL, TA = +25C, unless otherwise noted.)
MAX3244 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3224-10
MAX3244 SLEW RATE vs. LOAD CAPACITANCE
MAX3224-11
MAX3244 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps 250kbps 120kbps
MAX3224-12
TRANSMITTER OUTPUT VOLTAGE (V)
6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0
14 12 SLEW RATE (V/s) 10 8 6 4
60 50 SUPPLY CURRENT (mA) 40 30 20kbps 20 10 0
VOUT+ 1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps
VOUT1000 2000 3000 4000 5000
2 0 0 1000 2000 3000 4000 5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3245 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3224-13
MAX3245 SLEW RATE vs. LOAD CAPACITANCE
MAX3224-14
7.5 5.0 2Mbps 2.5 0 -2.5 -5.0 -7.5 0 400 800 1200 1600 1.5Mbps 1 TRANSMITTER AT FULL DATA RATE 2 TRANSMITTERS AT 1/16 DATA RATE 2Mbps 1.5Mbps 1Mbps 1Mbps
70 60 SLEW RATE (V/s) 50 40 30 20 10 0 1 TRANSMITTER AT 1Mbps 2 TRANSMITTERS AT 62.5kbps 0 400 800 1200 1600
2000
2000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3245 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
MAX3224-15
MAX3245 TRANSMITTER SKEW vs. LOAD CAPACITANCE
45 40 TRANSMITTER SKEW (ns)
MAX3224-16
100 90 80 SUPPLY CURRENT (mA) 70 60 50 40 30 20 10 0 0 400 800 1200 1600 1 TRANSMITTER AT FULL DATA RATE 2 TRANSMITTERS AT 1/16 DATA RATE 1Mbps 2Mbps 1.5Mbps
50
35 30 25 20 15 10 5 0
2000
0
1000
2000
3000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
Pin Description
PIN MAX3224 MAX3225 DIP/ TQFN SSIP/ TSSOP 1 2 3 4 5 6 7 8, 17 9, 16 10, 15 11 12, 13 14 18 19 20 19 1 20 2 3 4 5 6, 15 7, 14 8, 13 9 10, 11 12 16 17 18 NAME FUNCTION
MAX3224-MAX3227/MAX3244/MAX3245
MAX3226 MAX3227
MAX3244 MAX3245
1 2 3 4 5 6 7 13 8 9 10 11 12 14 15 16
-- 28 27 24 1 2 3 9, 10, 11 4-8 15-19 21 12, 13, 14 23 25 26 22
READY C1+ V+ C1C2+ C2VT_OUT R_IN R_OUT INVALID T_IN FORCEON GND VCC
Ready to Transmit Output, Active High. READY is enabled high when V- goes below -4V and the device is ready to transmit. Positive Terminal of Voltage-Doubler Charge-Pump Capacitor +5.5V Generated By the Charge Pump Negative Terminal of Voltage-Doubler Charge-Pump Capacitor Positive Terminal of Inverting Charge-Pump Capacitor Negative Terminal of Inverting Charge-Pump Capacitor -5.5V Generated By the Charge Pump RS-232 Transmitter Outputs RS-232 Receiver Inputs TTL/CMOS Transmitter Outputs Valid Signal Detector Output, Active Low. A logic-high indicates that a valid RS-232 level is present on a receiver input. TTL/CMOS Transmitter Inputs Force-On Input, Active High. Drive high to override AutoShutdown Plus, keeping transmitters and receivers on (FORCEOFF must be high) (Table 1). Ground +3.0V to +5.5V Single Supply Voltage
Force-Off Input, Active Low. Drive low to shut down transmitters, FORCEOFF receivers (except R2OUTB), and charge pump. This overrides AutoShutdown Plus and FORCEON (Table 1). R2OUTB EP TTL/CMOS Noninverting Complementary Receiver Outputs. Always active. Exposed Paddle. Solder the exposed paddle to the ground, or leave unconnected.
-- --
-- EP
-- --
20 --
_______________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.
LapLink is a trademark of Traveling Software.
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER FORCEOFF FORCEON INVALID PROTECTION DIODE VCC
MAX3244 MAX3245
VCC Rx UART Tx GND SHDN = GND I
PREVIOUS RS-232
5k
CPU
I/O CHIP WITH UART
RS-232
a)
OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN.
VCC TO P LOGIC TRANSITION DETECTOR
Figure 1. Interface Under Control of PMU
PROTECTION DIODE
I
MAX3244 MAX3245
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 3k in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLinkTM). Transmitters can be paralleled to drive multiple receivers. Figure 1 shows a complete system connection. When FORCEOFF is driven to ground or when the AutoShutdown 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 highimpedance 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.
R2OUTB
VCC Rx UART R2OUT THREE-STATED 5k T1IN FORCEOFF = GND T1OUT R2IN
Tx GND
b)
NEW MAX3244/MAX3245: 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 MAX3244/MAX3245 detect RS-232 activity when the UART and interface are shut down.
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
Table 1. Output Control Truth Table
OPERATION STATUS VALID RECEIVER LEVEL RECEIVER OR TRANSMITTER EDGE WITHIN 30sec X R_OUT (MAX3224/ MAX3225/ MAX3226/ MAX3227) Active R_OUT (MAX3244/ MAX3245) R2OUTB (MAX3244/ MAX3245)
FORCEON
FORCEOFF
T_OUT
Shutdown (Forced Off) Normal Operation (Forced On) Normal Operation (AutoShutdown Plus) Shutdown (AutoShutdown Plus) Normal Operation Normal Operation Shutdown Normal Operation (AutoShutdown) Shutdown (AutoShutdown)
X
0
X
High-Z
High-Z
Active
1
1
X
X
Active
Active
Active
Active
0
1
X
Yes
Active
Active
Active
Active
0 INVALID* INVALID* INVALID* INVALID*
1 1 1 1 INVALID**
X Yes X No Yes
No X Yes No X
High-Z Active Active High-Z Active
Active Active Active Active Active
Active Active Active Active Active
Active Active Active Active Active
INVALID*
INVALID**
No
X
High-Z
Active
High-Z
Active
X = Don't care
*INVALID connected to FORCEON **INVALID connected to FORCEON and FORCEOFF
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). 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 systems where V CC 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 receiver 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 1A 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 transmitter input for 30sec, the on-board charge pumps are shut down, reducing supply current to 1A. This occurs if the RS-232 cable is disconnected or if the connected
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
+0.3V T_IN EDGE DETECT FORCEOFF S 30sec TIMER R
R_IN
-0.3V
30s TIMER R
AUTOSHDN
INVALID
R_IN
EDGE DETECT
INVALID ASSERTED IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30s.
FORCEON
Figure 3a. INVALID Functional Diagram, INVALID Low
Figure 3c. AutoShutdown Plus Logic
+2.7V
FORCEOFF
POWERDOWN*
R_IN
FORCEON 30s TIMER R INVALID AUTOSHDN
-2.7V
INVALID DEASSERTED IF ANY RECEIVER INPUT HAS BEEN BETWEEN +2.7V AND -2.7V FOR LESS THAN 30s.
* POWERDOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES.
Figure 3b. INVALID Functional Diagram, INVALID High
Figure 3d. Power-Down Logic
Table 2. INVALID Truth Table
RS-232 SIGNAL PRESENT AT ANY RECEIVER INPUT Yes No
INVALID HIGH
INVALID OUTPUT
RECEIVER INPUT LEVELS
+2.7V INDETERMINATE +0.3V 0 -0.3V INDETERMINATE -2.7V INVALID HIGH
High Low
INVALID LOW
peripheral transmitters are turned off, and the UART driving 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 system saves power without changes to the existing BIOS or operating system. 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 summarize 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
Figure 4a. Receiver Positive/Negative Thresholds for INVALID
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 transmitter outputs are high impedance, and READY (MAX3224-MAX3227) is driven low. The time required to exit shutdown is typically 100s (Figure 8).
10
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1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
RECEIVER INPUTS
} REGION
INVALID
TRANSMITTER INPUTS
TRANSMITTER OUTPUTS VCC 0 *VCC OUTPUT 0 V+ VCC 0 V*MAX3224-MAX3227
INVALID OUTPUT
tINVL
tINVH tAUTOSHDN tWU
tAUTOSHDN tWU
Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram
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 when a valid receiver level is detected (same functionality 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.
POWERMANAGEMENT UNIT
MASTER SHDN LINE 0.1F 1M
FORCEOFF FORCEON
MAX3224 MAX3225 MAX3226 MAX3227 MAX3244 MAX3245
Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a Mouse or Another System
______________________________________________________________________________________
11
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
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. transmitter is loaded with 3k in parallel with 1000pF. 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.
FORCEON = FORCEOFF T1OUT
__________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 0.1F capacitors for 3.3V operation. For other supply voltages, see 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, 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 capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-.
5V/div 0
2V/div 0
5V/div 0
VCC = 3.3V C1-C4 = 0.1F 5s/div
T2OUT READY
Figure 6. Transmitter Outputs when Exiting Shutdown or Powering Up
VCC CBYPASS VCC
Power-Supply Decoupling
In most circumstances, a 0.1F VCC bypass capacitor is adequate. In applications that are sensitive to powersupply noise, use a capacitor of the same value as charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible.
C1
C1+ C1C2+ C2 C2-
V+ C3*
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 (one transmitter input is high; the other is low). Each
MAX3224 MAX3225 MAX3226 MAX3227 MAX3244 MAX3245
VC4
T_ IN
T_ OUT
R_ OUT
R_ IN 5k
Table 3. Required Minimum Capacitance Values
VCC (V) 3.0 to 3.6 4.5 to 5.5 3.0 to 5.5 C1, CBYPASS (F) 0.1 0.047 0.22 C2, C3, C4 (F) 0.1 0.33 1
FORCEON VCC FORCEOFF
1000pF
GND
*C3 CAN BE RETURNED TO VCC OR GND.
Figure 7. Loopback Test Circuit
12
______________________________________________________________________________________
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
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 simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 9, a single transmitter was driven 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 parallel with 250pF.
MAX3224-MAX3227/MAX3244/MAX3245
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
T1IN
5V/div
T1IN
5V/div
5V/div T1OUT
T1OUT
5V/div
R1OUT VCC = 3.3V 2s/div
5V/div
R1OUT VCC = 3.3V 200ns/div
5V/div
Figure 8. MAX3224/MAX3226/MAX3244 Loopback Test Result at 120kbps
Figure 10. MAX3225/MAX3227/MAX3245 Loopback Test Result at 1Mbps
TRANSMITTER OUTPUT VOLTAGE (V)
6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0 VCC VOUTVOUTVCC = 3.0V VOUT+ VOUT+
T1IN
5V/div
T1OUT
5V/div
R1OUT VCC = 3.3V 2s/div
5V/div
1
2
3
4
5
6
7
8
9
10
LOAD CURRENT PER TRANSMITTER (mA)
Figure 9. MAX3224/MAX3226/MAX3244 Loopback Test Result at 250kbps
Figure 11a. MAX324_ Transmitter Output Voltage vs. Load Current per Transmitter
13
______________________________________________________________________________________
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
+3.3V 0.1F 28 C1 0.1F 24 1 C2 0.1F 2 14 C1+ C1C2+ C2T1IN T1OUT 9 +V 26 VCC V+ 27 C3 0.1F 3 VC4 0.1F
COMPUTER SERIAL PORT
MAX3244 MAX3245
LOGIC INPUTS
13
T2IN
T2OUT
10
+V
12
T3IN
T3OUT
11
-V
20
R2OUTB
GND
19
R1OUT 5k
R1IN
4
Tx
18 LOGIC OUTPUTS 17
R2OUT
R2IN 5k
5
R3OUT 5k
R3IN
6
RS-232 INPUTS
16
R4OUT 5k
R4IN
7
15 23 22
R5OUT
R5IN 5k
8
SERIAL MOUSE
FORCEON FORCEOFF INVALID
VCC TO POWERMANAGEMENT UNIT
21
GND 25
Figure 11b. Mouse Driver Test Circuit
14 ______________________________________________________________________________________
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
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.
Interconnection with 3V and 5V Logic
The MAX3224-MAX3227/MAX3244/MAX3245 can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 4 for more information on possible combinations of interconnections. Table 5 lists other Maxim 3.0V to 5.5V powered transceivers.
MAX3224-MAX3227/MAX3244/MAX3245
Table 4. Logic Family Compatibility with Various Supply Voltages
SYSTEM POWER-SUPPLY VOLTAGE (V) 3.3 5 5 VCC SUPPLY VOLTAGE (V) 3.3 5 3.3 COMPATIBILITY
Compatible with all CMOS families Compatible with all TTL and CMOS families Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS
Table 5. 3.0V to 5.5V Powered RS-232 Transceivers from Maxim
PART SUPPLY VOLTAGE RANGE (V) +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 +3.0 to +5.5 NO. OF Tx/Rx 3/5 3/5 3/5 3/5 2/2 2/2 2/2 2/2 2/2 1/1 1/1 1/1 SUPPLY CURRENT (A) 300 1 1 1 300 300 1 1 1 1 1 1 AUTOSHUTDOWN PLUS -- -- Yes Yes -- -- -- Yes Yes -- Yes Yes AUTOSHUTDOWN -- Yes -- -- -- -- Yes -- -- Yes -- -- GUARANTEED DATA RATE (bps) 120k 120k 250k 1M 120k 120k 120k 250k 1M 120k 250k 1M
MAX3241 MAX3243 MAX3244 MAX3245 MAX3232 MAX3222 MAX3223 MAX3224 MAX3225 MAX3221 MAX3226 MAX3227
______________________________________________________________________________________
15
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
___________________________________________________Typical Operating Circuits
+3.3V +3.3V CBYPASS C1 0.1F 0.1F 2 C1+ 4 C15 C2 0.1F 6 C2+ C2T1OUT 13 15 VCC V+ 3 C3 0.1F 7 C4 0.1F C2 0.1F C1 0.1F CBYPASS 0.1F 28 C1+ 24 1 2 C1C2+ C2T1OUT 9 T2OUT 10 T3OUT 11 26 VCC V+ C3 0.1F 27
MAX3226 MAX3227
V-
MAX3244 MAX3245
V-
3 C4 0.1F
11 T1IN
14 T1IN 13 T2IN 12 T3IN TO POWERMANAGEMENT UNIT VCC 22 FORCEOFF 23 FORCEON 20 R2OUTB 19 R1OUT AUTOSHUTDOWN PLUS
9 R1OUT
R1IN 8 5k
1 READY
AUTOSHUTDOWN INVALID 10 PLUS FORCEOFF 16 GND 14
INVALID 21
12
FORCEON
R1IN 4 5k
+3.3V CBYPASS C1 0.1F 0.1F 2 C1+ 4 C15 C2 0.1F 6 C2+ C2T1OUT 17 RS-232 OUTPUTS 15 R5OUT 19 VCC V+ 3 C3 0.1F 7 C4 0.1F 16 R4OUT 17 R3OUT 18 R2OUT
R2IN 5k
5
MAX3224* MAX3225*
R3IN 6 5k R4IN 7 5k R5IN 8 5k
V-
13 T1IN TTL/CMOS INPUTS
12 T2IN
T2OUT 8
15 R1OUT TTL/CMOS OUTPUTS 10 R2OUT
R1IN 16 5k R2IN 5k TO POWERMANAGEMENT UNIT VCC *MAX3224/MAX3225 PINOUT REFERS TO DIP/SSOP/TSSOP PACKAGES. 9 RS-232 INPUTS GND 25
1 READY
AUTOSHUTDOWN PLUS
INVALID 11
14
FORCEON GND 18
FORCEOFF 20
16
______________________________________________________________________________________
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
___________________________________________________________ Pin Configurations
MAX3224-MAX3227/MAX3244/MAX3245 MAX3224-MAX3227/MAX3244/MAX3245
READY 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8
20 FORCEOFF 19 VCC 18 GND 17 T1OUT
READY 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 R1IN 8
16 FORCEOFF 15 VCC 14 GND
MAX3224 MAX3225
16 R1IN 15 R1OUT 14 FORCEON 13 T1IN 12 T2IN 11 INVALID
MAX3226 MAX3227
13 T1OUT 12 FORCEON 11 T1IN 10 INVALID 9 R1OUT
R2IN 9 R2OUT 10
SSOP
DIP/SSOP/TSSOP
FORCEON
C2+ 1 C2- 2 T1IN V- 3 R1IN 4 R2IN 5
28 C1+ 27 V+ 26 VCC 25 GND
15
14
13
R1OUT
T1OUT
R1IN
12
11
GND 16 VCC 17 FORCEOFF 18 READY 19 V+ 20
10 9
T2IN INVALID R2OUT R2IN T2OUT
R3IN 6 R4IN 7 R5IN 8 T1OUT 9 T2OUT 10 T3OUT 11 T3IN 12
MAX3244 MAX3245
24 C123 FORCEON 22 FORCEOFF 21 INVALID 20 R2OUTB 19 R1OUT 18 R2OUT 17 R3OUT 16 R4OUT 15 R5OUT
MAX3244 MAX3225
EXPOSED PADDLE
8 7 6
1 C1+
2 C1-
3 C2+
4 C2-.
5 V-
T2IN 13 T1IN 14
TQFN
SO/SSOP
______________________________________________________________________________________
17
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
_ Ordering Information (continued)
PART MAX3225CPP MAX3225CAP MAX3225CTP MAX3225CUP MAX3225EPP MAX3225EAP MAX3225ETP MAX3225EUP MAX3225EUP/V MAX3226CAE MAX3226EAE MAX3227CAE MAX3227EAE MAX3244CWI MAX3244CAI MAX3244EWI MAX3244EAI MAX3245CWI MAX3245CAI MAX3245EWI TEMP RANGE 0C to +70C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C 0C to +70C -40C to +85C 0C to +70C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C PIN-PACKAGE 20 Plastic DIP 20 SSOP 20 Thin QFN-EP* 20 TSSOP 20 Plastic DIP 20 SSOP 20 Thin QFN-EP* 20 TSSOP 20 TSSOP 16 SSOP 16 SSOP 16 SSOP 16 SSOP 28 Wide SO 28 SSOP 28 Wide SO 28 SSOP 28 Wide SO 28 SSOP 28 Wide SO 28 SSOP
___________________Chip Information
MAX3224 TRANSISTOR COUNT: 1129 MAX3225 TRANSISTOR COUNT: 1129 MAX3226 TRANSISTOR COUNT: 1129 MAX3227 TRANSISTOR COUNT: 1129 MAX3244/MAX3245 TRANSISTOR COUNT: 1335
PROCESS: BiCMOS
MAX3245EAI -40C to +85C *EP = Exposed paddle. /V denotes an automotive qualified part.
18
______________________________________________________________________________________
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 16 SSOP 20 SSOP 20 Thin QFN-EP 20 TSSOP 20 Plastic DIP 28 Wide SO 28 SSOP PACKAGE CODE -- T4477-3 T2055-5 -- -- -- -- DOCUMENT NO. 21-0056 21-0056 21-0140 21-0108 21-0043 21-0042 21-0056
MAX3224-MAX3227/MAX3244/MAX3245
______________________________________________________________________________________
19
1A Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus MAX3224-MAX3227/MAX3244/MAX3245
Revision History
REVISION NUMBER 2 3 REVISION DATE 5/05 10/08 Added new packaging types Added automotive qualified product information DESCRIPTION PAGES CHANGED 1, 18
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 (c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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