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19-0380; Rev 0; 3/95
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM
_______________General Description
The MAX3218 RS-232 transceiver is intended for battery-powered EIA/TIA-232E and V.28/V.24 communications interfaces that need two drivers and two receivers with minimum power consumption from a single lowvoltage supply. It provides a wide +1.8V to +4.25V operating voltage range while maintaining true RS-232 and EIA/TIA-562 voltage levels. The MAX3218 runs from two alkaline, NiCd, or NiMH cells without any form of voltage regulator. A guaranteed 120kbps data rate provides compatibility with popular software for communicating with personal computers. Supply current is reduced to 1A with Maxim's new AutoShutdownTM feature. When the MAX3218 does not sense a valid signal level on the receiver inputs, the onboard 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 either RS-232 receiver input. As a result, the system saves power without changes to the existing software. Additionally, the MAX3218 can be forced into or out of shutdown, under logic control. While shut down, all receivers can remain active or can be disabled under logic control, permitting a system incorporating the CMOS MAX3218 to monitor external devices while in low-power shutdown. Three-state drivers are provided on both receiver outputs so that multiple receivers, generally of different interface standards, can be on the same bus. The MAX3218 is available in 20-pin DIP and SSOP packages.
____________________________Features
BETTER THAN BIPOLAR! o 1A Supply Current Using AutoShutdownTM o Operates Directly from Two Alkaline, NiCd or NiMH Cells o +1.8V to +4.25V Single-Supply Voltage Range o 120kbps Data Rate Guaranteed o Low-Cost Surface-Mount Components o Meets EIA/TIA-232E Specifications o Three-State Receiver Outputs o Flow-Through Pinout o On-Board DC-DC Converters o 20-Pin SSOP and DIP Packages
MAX3218*
______________Ordering Information
PART MAX3218CPP MAX3218CAP MAX3218C/D MAX3218EPP MAX3218EAP TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 20 Plastic DIP 20 SSOP Dice 20 Plastic DIP 20 SSOP
Contact factory for dice specifications.
________________________Applications
Battery-Powered Equipment Subnotebook Computers PDAs Hand-Held Equipment Peripherals Cellular Phones
__________________Pin Configuration
TOP VIEW
LX 1 INVALID 2 FORCEON 3 FORCEOFF 4 GND 5 VCC 6 T1IN 7 T2IN 8 R1OUT 9 R2OUT 10 20 GND 19 V+ 18 C1+ 17 GND
MAX3218
16 C115 V14 T1OUT 13 T2OUT 12 R1IN 11 R2IN
* Patent Pending TM AutoShutdown is a trademark of Maxim Integrated Products.
DIP/SSOP 1
________________________________________________________________ Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM MAX3218
ABSOLUTE MAXIMUM RATINGS
Supply Voltages VCC ....................................................................-0.3V to +4.6V V+ .......................................................... (VCC - 0.3V) to +7.5V V- .......................................................................+0.3V to -7.4V VCC to V- ..........................................................................+12V LX ................................................................-0.3V to (1V + V+) Input Voltages T_IN, FORCEON, FORCEOFF ............................ -0.3V to +7V R_IN .................................................................................25V Output Voltages T_OUT.............................................................................15V) R_OUT ....................................................-0.3V to (VCC + 0.3V) Short-Circuit Duration, R_OUT, T_OUT to GND ....... Continuous Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 11.11mW/C above +70C) ..........889mW SSOP (derate 8.00mW/C above +70C) ..................640mW Operating Temperature Ranges MAX3218C_ P ................................................... 0C to +70C MAX3218E_ P ................................................. -40C to +85C Storage Temperature Range ........................... -65C to +150C Lead Temperature (soldering, 10sec) ........................... +300C
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
(Circuit of Figure 1, VCC = 1.8V to 4.25V, C1 = 0.47F, C2 = C3 = C4 = 1F, L1 = 15H, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3.0V, TA = +25C.) PARAMETER DC CHARACTERISTICS Operating Voltage Range VCC = 3.0V, TA = +25C, all R_IN open, Supply Current, AutoShutdownTM FORCEON = GND, FORCEOFF = VCC Supply Current, Shutdown Supply Current, AutoShutdownTM Disabled Input Logic Threshold Low Input Logic Threshold High Input Leakage Current Output Voltage Low Output Voltage High Output Leakage Current FORCEOFF = GND, TA = +25C, VCC = 3.0V FORCEON = FORCEOFF = VCC = 3.0V, no load 1.8 1.0 1.0 2.0 4.25 10 10 3.0 V A A mA CONDITIONS MIN TYP MAX UNITS
LOGIC INPUTS AND RECEIVER OUTPUTS T_IN, FORCEON, FORCEOFF T_IN, FORCEON, FORCEOFF T_IN, FORCEON = FORCEOFF = 0V or VCC R_OUT, IOUT = 1.0mA R_OUT, IOUT = -0.4mA R_OUT, 0V R_OUT VCC, FORCEON = FORCEOFF = 0V Positive threshold Negative threshold VCC - 0.25 VCC - 0.08 0.05 10 0.67 x VCC 0.001 1 0.4 0.33 x VCC V V A V V A
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC) Receiver Input Thresholds, Transmitters Enabled Receiver Input Thresholds Transmitters Disabled INVALID Output Low Voltage INVALID Output High Voltage Figure 4a 2.8 -2.8 -0.3 0.3 0.4 VCC - 0.25 V V V V
1A supply current, Figure 4a IOUT = 1.0mA, -0.3V < R_IN < 0.3V IOUT = -0.4mA, |R_IN| > 2.8V
2
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1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, VCC = 1.8V to 4.25V, C1 = 0.47F, C2 = C3 = C4 = 1F, L1 = 15H, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3.0V, TA = +25C.) PARAMETER EIA/TIA-232E RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance Output Voltage Swing Output Resistance Output Short-Circuit Current -15V < R_IN < 15V All transmitter outputs loaded with 3k to ground VCC = 0V, -2V < T_OUT < 2V 3 5 300 24 100 EIA/TIA-232E TRANSMITTER OUTPUTS 6 V mA VCC = 2.0V to 4.25V VCC = 1.8V to 4.25V VCC = 1.8V to 4.25V VCC = 1.8V to 3.6V 0.7 5 7 -25 0.4 0.3 3.0 2.8 +25 V V V V k CONDITIONS MIN TYP MAX UNITS
MAX3218
TIMING CHARACTERISTICS
(Circuit of Figure 1, VCC = 1.8V to 4.25V, C1 = 0.47F, C2 = C3 = C4 = 1F, L1 = 15H, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3.0V, TA = +25C.) PARAMETER Data Rate Receiver Output Enable Time Receiver Output Disable Time Transmitter Output Enable Time Transmitter Output Disable Time Receiver Propagation Delay Transmitter Propagation Delay tER tDR tET tDT tPHLR tPLHR tPHLT tPLHT 150pF load 150pF load 2500pF || 3k load 2500pF || 3k load TA = +25C, VCC = 3.0V, RL = 3k to 7k, CL = 50pF to 2500pF, measured from +3V to -3V or -3V to +3V 3.0 SYMBOL CONDITIONS 2500pF || 3k load each transmitter, one transmitter switching, 150pF load each receiver MIN 120 TYP 235 90 200 250 500 290 260 1.9 1.8 1000 1000 2.7 2.7 30 300 500 450 MAX UNITS kbps ns ns s ns ns s
Transition Region Slew Rate AUTOSHUTDOWN TIMING Receiver Threshold to Transmitters Enabled Receiver Positive or Negative Threshold to INVALID High Receiver Positive or Negative Threshold to INVALID Low tWU tINVH tINVL
V/s
Figure 4b Figure 4b Figure 4b
250 1 30
s s s
_______________________________________________________________________________________
3
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM MAX3218
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, VCC = 1.8V, all transmitter outputs loaded with 3k, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX3218-01
TRANSMITTING SUPPLY CURRENT vs. LOAD CAPACITANCE
VCC = 2.4V 90 SUPPLY CURRENT (mA) 80 70 60 50 40 30 20 20kbps 1000 120kbps 235kbps TRANSMITTER 1 OPERATING AT SPECIFIED BIT RATE, TRANSMITTER 2 OPERATING AT 1/16 THAT RATE.
MAX3218-02
140 120 SUPPLY CURRENT (mA) 100 240kbps 80 60 40 20 0 1.8 2.4 3.0 3.6 4.2 SUPPLY VOLTAGE (V) 120kbps 20kbps 0kbps 1 TRANSMITTER FULL DATA RATE 1 TRANSMITTER 1/8 DATA RATE RL = 3k + 2500pF
100
0
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
TIME TO EXIT SHUTDOWN (ONE TRANSMITTER HIGH, ONE TRANSMITTER LOW)
FORCEON, FORCEOFF VOH
2V/div T_OUT
VCC = 1.8V RL = 3k || 2500pF 100s/div
VOL
TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE AT 120kbps
MAX3218-04
SLEW RATE vs. TRANSMITTER CAPACITANCE
MAX3218-05
8 TRANSMITTER OUTPUT VOLTAGE (V) 6 4 2 0 -2 -4 VOUT-6 -8 0 1000 2000 3000 4000 VOUT+
12 10 SLEW RATE (V/s) +SLEW 8 6 4 2 0 DATA RATE 120kbps, TRANSMITTERS LOADED WITH 3k PLUS INDICATED CAPACITANCE 0 1000 2000 3000 4000 -SLEW
5000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
4
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1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM
______________________________________________________________Pin Description
PIN NAME LX INVALID FORCEON FORCEOFF GND VCC T1IN, T2IN R1OUT, R2OUT R2IN, R1IN T2OUT, T1OUT VC1-, C1+ V+ Inductor/Diode Connection Point Output of Invalid Signal Detector. Low if invalid RS-232 levels are present on all receiver inputs, otherwise high. Drive high when FORCEOFF = high to override automatic circuitry, keeping transmitters on. Drive low to shut down transmitters and on-board power supply, overriding all automatic circuitry and FORCEON. Ground Supply Voltage Input, 1.8V to 4.25V. Bypass to GND with at least 1F. Transmitter Inputs Receiver Outputs Receiver Inputs Transmitter Outputs, swing between V+ and VNegative Supply generated on-board Terminal for Charge-Pump Capacitor Positive Supply generated on-board FUNCTION
MAX3218
1
2 3 4 5, 17, 20 6 7, 8 9, 10 11, 12 13, 14 15 16, 18 19
_______________Detailed Description
The MAX3218 line driver/receiver is intended for battery-powered EIA/TIA-232 and V.28/V.24 communications interfaces that require two drivers and two receivers. The operating voltage extends from 1.8V to 4.25V, yet the device maintains true RS-232 and EIA/TIA-562 transmitter output voltage levels. This wide supply voltage range permits direct operation from a variety of batteries without the need for a voltage regulator. For example, the MAX3218 can be run directly from a single lithium cell or a pair of alkaline cells. It can also be run directly from two NiCd or NiMH cells from full-charge voltage down to the normal 0.9V/cell end-of-life point. The 4.25V maximum supply voltage allows the two rechargeable cells to be trickle- or fastcharged while driving the MAX3218. The circuit comprises three sections: power supply, transmitters, and receivers. The power-supply section converts the supplied input voltage to 6.5V, providing the voltages necessary for the drivers to meet true RS-232 levels. External components are small and inexpensive. The transmitters and receivers are guaranteed to operate at 120kbps data rates, providing compatibility with LapLinkTM and other high-speed communications software.
The MAX3218 is equipped with Maxim's new proprietary AutoShutdownTM circuitry. This achieves a 1A supply current by shutting down the device when the RS-232 cable is disconnected or when the connected peripheral transmitters are turned off. While shut down, both receivers can remain active or can be disabled under logic control. With this feature, the MAX3218 can be in low-power shutdown mode and still monitor activity on external devices. Three-state drivers are provided on both receiver outputs. Three-state drivers on both receiver outputs are provided so that multiple receivers, generally of different interface standards, can be wire-ORed at the UART.
Switch-Mode Power Supply
The switch-mode power supply uses a single inductor with one diode and three small capacitors to generate 6.5V from an input voltage in the 1.8V to 4.25V range.
Inductor Selection Use a 15H inductor with a saturation current rating of at least 350mA and less than 1 resistance. Table 1 lists suppliers of inductors that meet the 15H/350mA/1 specifications.
TM LapLink is a trademark of Traveling Software, Inc. AutoShutdown is a trademark of Maxim Integrated Products.
_______________________________________________________________________________________
5
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM MAX3218
Table 1. Suggested Component Suppliers
MANUFACTURER Inductors Murata-Erie Sumida TDK Diodes--Surface-Mount Allegro Central Semiconductor Motorola Philips Diodes--Through-Hole Motorola 1N6050 (silicon), 1N5817 (Schottky) USA (408) 749-0510 USA (408) 991-7420 TMPD6050LT CMPSH-3 (Schottky) MMBD6050LT1 (silicon) PMBD6050 (silicon) USA (508) 853-5000 USA (516) 435-1110 USA (408) 749-0510 USA (401) 762-3800 USA (508) 853-7556 USA (516) 435-1824 USA (408) 991-7420 USA (401) 767-4493 LQH4N150K-TA CD43150 NLC453232T-150K USA (814) 237-1431 USA (708) 956-0666 Japan (03) 3607-5111 USA (708) 803-6100 Japan (03) 3278-5111 USA (814) 238-0490 USA (708) 956-0702 Japan (03) 3607-5428 USA (708) 803-6296 Japan (03) 3278-5358 PART NUMBER PHONE FAX
Diode Selection Key diode specifications are fast recovery time (<10ns), average current rating (>100mA), and peak current rating (>350mA). Inexpensive fast silicon diodes, such as the 1N6050, are generally recommended. More expensive Schottky diodes improve efficiency and give slightly better performance at very low VCC voltages. Table 1 lists suppliers of both surface-mount and through-hole diodes. 1N914s are usually satisfactory, but specifications and performance vary widely with different manufacturers. Capacitor Selection Use capacitors with values at least as indicated in Figure 1. Capacitor C2 determines the ripple on V+, but not the absolute voltage. Capacitors C1 and C3 determine both the ripple and the absolute voltage of V-. Bypass VCC to GND with at least 1F (C4) placed close to pins 5 and 6. If the VCC line is not bypassed elsewhere (e.g., at the power supply), increase C4 to 4.7F. You may use ceramic or polarized capacitors in all locations. If you use polarized capacitors, tantalum types are preferred because of the high operating frequency of the power supplies (about 250kHz). If aluminum electrolytics are used, higher capacitance values may be required.
1.8V to 4.25V
15H C4 1F 6 VCC 3 4 2 FORCEON FORCEOFF INVALID T1 1 LX
1N6050 19 V+ VC2 1F 15 C3 1F 18 16 C1 0.47F
MAX3218
C1+ C1-
7 T1IN
T1OUT 14
8 T2IN 9 R1OUT
T2 R1
T2OUT 13 R1IN 12 5k
10 R2OUT
R2 5k
R2IN 11
GND 5, 17, 20
Figure 1. Typical Operating Circuit
6
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1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM MAX3218
Table 2. Receiver Status
POWER MANAGEMENT UNIT OR KEYBOARD CONTROLLER FORCEOFF FORCEON INVALID
FORCEON X H
MAX3218
FORCEOFF H X L
RECEIVER STATUS Receiver Enabled Receiver Disabled
L
Shutdown
I/O CHIP WITH UART
CPU
RS-232
When FORCEOFF is low, power supplies are disabled and the transmitters are placed in a high-impedance state. Receiver operation is not affected by taking FORCEOFF low. Power consumption is dramatically reduced in shutdown mode. Supply current is minimized when the receiver inputs are static in any one of three states: floating (ground), GND, or VCC.
AutoShutdownTM
A 1A supply current is achieved with Maxim's new AutoShutdown feature, which operates when FORCEON is low and FORCEOFF is high. When the MAX3218 senses no valid signal level on either receiver input for typically 30s, the on-board power supply and drivers shut down, reducing supply current to 1A. Internal 5k resistors pull undriven receiver inputs to ground. This occurs if the RS-232 cable is disconnected or if the connected peripheral transmitters are turned off. The system turns on again when a valid level is applied to either RS-232 receiver input. As a result, the system saves power without changes to the existing BIOS or operating system. When using the AutoShutdown feature, INVALID is high when the device is on and low when the device is shut down. The INVALID output indicates the condition of the receiver inputs. Table 3 summarizes the MAX3218 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. Figure 4 depicts valid and invalid RS-232 receiver levels. The
Figure 2. Interface Under Control of PMU
RS-232 Drivers
The two drivers are identical, and deliver EIA/TIA-232E and EIA/TIA-562 output voltage levels when V CC is between 1.8V and 4.25V. One transmitter can drive up to 3k in parallel with 2500pF at up to 120kbps. Connect unused drivers to either GND or V CC. When FORCEOFF is driven low, or when AutoShutdown circuitry senses invalid voltage levels at all receiver inputs, the drivers are disabled and their outputs are forced into a high-impedance state. Driver inputs do not have internal pull-up resistors.
RS-232 Receivers
The two receivers are identical, and accept both EIA/TIA-232E and EIA/TIA-562 input signals. The CMOS receiver outputs are inverting and swing rail-torail. Receivers are disabled only when FORCEON and FORCEOFF inputs are low. (See Table 2.)
Table 3. AutoShutdown Logic
RS-232 SIGNAL PRESENT AT RECEIVER INPUT Yes No No Yes No FORCEOFF INPUT H H H L L FORCEON INPUT X H L X X INVALID OUTPUT H L L H L TRANSCEIVER STATUS Normal Operation Normal Operation (Forced On) Shutdown (AutoShutdown) Shutdown (Forced Off) Shutdown (Forced Off) 7
_______________________________________________________________________________________
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM
MAX3218 shuts down after sensing invalid RS-232 levels for greater than 30s, ensuring that the AutoShutdown mode is not enabled for slow-moving signals (>1V/s). Another system with AutoShutdown may need a period of time to wake up. Figure 5 shows a circuit that forces the transmitters on for 100ms after start-up, allowing enough time for the other system to realize that the MAX3218 system is awake. If the other system outputs valid RS-232 signals within that time, the RS-232 ports on both systems remain enabled.
MAX3218
drawn directly from the battery, without suffering the efficiency losses of the DC-DC converter. This prolongs battery life. Bypass the input supplies with 0.1F at VCC (C4) and at least 1F at the inductor (C5). Increase C5 to 4.7F if the power supply has no other bypass capacitor connected to it.
Low-Power Operation
The following suggestions will help you get maximum life out of your batteries. Transmit at the highest practical data rate. Although this raises the supply current while transmission is in progress, the transmission will be over sooner. If the MAX3218 is shut down (using FORCEOFF) as soon as each transmission ends, this practice will save energy. Operate your whole system from the raw battery voltage rather than suffer the losses of a regulator or DCDC converter. If this is not possible, but your system is powered from two cells and employs a 3V DC-DC converter to generate the main logic supply, use the circuit of Figure 6. This circuit draws most of the MAX3218's power straight from the battery, but still provides logiclevel compatibility with the 3V logic.
__________Applications Information
Operation from Regulated/Unregulated Dual System Power Supplies
The MAX3218 is intended for use with three different power-supply sources: it can be powered directly from a battery, from a 3.0V or 3.3V power supply, or simultaneously from both. Figure 1 shows the single-supply configuration. Figure 6 shows the circuit for operation from both a 3V supply and a raw battery supply--an ideal configuration where a regulated 3V supply is being derived from two cells. In this application, the MAX3218's logic levels remain appropriate for interface with 3V logic, yet most of the power for the MAX3218 is
+0.3V to +2.8V
+ FORCEOFF + POWER DOWN
-0.3V to -2.8V
FORCEON
R_IN
Rx
R_OUT
FORCEON FORCEOFF
* * *
* * *
30s DELAY
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.
FORCEOFF 0 0 0 0 1 1 1 1
FORCEON 0 0 1 1 0 0 1 1
INVALID 0 1 0 1 0 1 0 1
POWER DOWN 0 0 0 0 0 1 1 1
Figure 3. AutoShutdown Logic
8 _______________________________________________________________________________________
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM
Keep communications cables short to minimize capacitive loading. Lowering the capacitive loading on the transmitter outputs reduces the MAX3218's power consumption. Using short, low-capacitance cable also helps transmission at the highest data rates.
MAX3218
AUTOSHUTDOWN RECEIVER INPUT THRESHOLD (V)
TRANSMITTERS ENABLED, INVALID HIGH +2.8V INDETERMINATE +0.3V 0V -0.3V INDETERMINATE -2.8V TRANSMITTERS ENABLED, INVALID HIGH AUTOSHUTDOWN, TRANSMITTERS DISABLED, 1A SUPPLY CURRENT, INVALID LOW
EIA/TIA-232E and _____________EIA/TIA-562 Standards
RS-232 circuits consume much of their power because the EIA/TIA-232E standard demands that the transmitters deliver at least 5V to receivers with impedances that can be as low as 3k. For applications where power consumption is critical, the EIA/TIA-562 standard provides an alternative. EIA/TIA-562 transmitter output voltage levels need only reach 3.7V, and because they have to drive the same 3k receiver loads, the total power consumption is considerably reduced. Since the EIA/TIA-232E and EIA/TIA-562 receiver input voltage thresholds are the same, interoperability between EIA/TIA-232E and EIA/TIA-562 devices is guaranteed. Maxim's MAX560 and MAX561 are EIA/TIA-562 transceivers that operate on a single supply from 3.0V to 3.6V, and the MAX562 transceiver operates from 2.7V to 5.25V while producing EIA/TIA-562 levels.
(a)
RECEIVER INPUT VOLTAGE (V)
INVALID REGION
VCC INVALID OUTPUT (V) 0
POWER MANAGEMENT UNIT tINVL tINVH
MASTER SHDN LINE 0.1F 1M
V+ VCC 0V VtWU
FORCEOFF FORCEON
MAX3218
(b)
Figure 4. AutoShutdown Trip Levels
Figure 5. AutoShutdown with Initial Turn-On to Wake Up a System
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9
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM MAX3218
15H C5 1F 6 C4 0.1F 3 4 2 1 LX 19 V+ V15 C3 1F 18 C1 0.47F C1- 16 T1OUT 14 1N6050 1F C2
3V DC-DC CONVERTER
MAX878 OR MAX756 OR MAX856
VCC
FORCEON FORCEOFF INVALID C1+
MAX3218
T1
7 T1IN
8 T2IN 9 R1OUT
T2 R1
T2OUT 13 R1IN 12 5k
10
R2OUT
R2 5k
R2IN 11
GND 5, 17, 20
Figure 6. Operating from Unregulated and Regulated Supplies
10
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1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM
_____+3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
SUPPLY VOLTAGE (V) 3.0 to 3.6 2.7 to 3.6 No. OF TRANSMITTERS/ RECEIVERS 3/5 3/5 No. OF RECEIVERS ACTIVE IN SHUTDOWN 5 5 GUARANTEED DATA RATE (kbps) 120 120 EIA/TIA232 OR 562 232 232
MAX3218
PART
FEATURES
MAX212 MAX3212
Drives mice AutoShutdown, complementary receiver, drives mice, transient detection Operates directly from a battery without a voltage regulator Same as MAX218 but with AutoShutdown Pin-compatible with MAX213 Pin-compatible with MAX214 Wide supply range 0.1F capacitors 0.1F capacitors AutoShutdown, 0.1F capacitors Pin-compatible with MAX232 0.1F capacitors, 2 complementary receivers, drives mice 0.1F capacitors, AutoShutdown, complementary receiver, drives mice
MAX218 MAX3218 MAX560 MAX561 MAX562 MAX563 MAX3222 MAX3223 MAX3232 MAX3241
1.8 to 4.25 1.8 to 4.25 3.0 to 3.6 3.0 to 3.6 2.7 to 5.25 3.0 to 3.6 3.0 to 5.5 3.0 to 5.5 3.0 to 5.5 3.0 to 5.5
2/2 2/2 4/5 4/5 3/5 2/2 2/2 2/2 2/2 3/5
2 2 2 0 5 2 2 2 2 5
120 120 120 120 230 120 120 120 120 120
232 232 562 562 562 562 232 232 232 232
MAX3243
3.0 to 5.5
3/5
1
120
232
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11
1A Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdownTM MAX3218
___________________Chip Topography
INVALID LX FORCEON C1+ FORCEOFF GND C1V0.101" (2.565mm) GND V+
GND V CC T1IN T2IN R1IN R2OUT R2IN R1OUT 0.122" (3.099mm) T1OUT T2OUT
TRANSISTOR COUNT: 571 SUBSTRATE CONNECTED TO GND
________________________________________________________Package Information
DIM A A1 B C D E e H L INCHES MILLIMETERS MIN MAX MIN MAX 0.068 0.078 1.73 1.99 0.002 0.008 0.05 0.21 0.010 0.015 0.25 0.38 0.004 0.008 0.09 0.20 SEE VARIATIONS 0.205 0.209 5.20 5.38 0.0256 BSC 0.65 BSC 0.301 0.311 7.65 7.90 0.025 0.037 0.63 0.95 0 8 0 8 INCHES MILLIMETERS MAX MIN MAX MIN 6.33 0.239 0.249 6.07 6.33 0.239 0.249 6.07 7.33 0.278 0.289 7.07 8.33 0.317 0.328 8.07 0.397 0.407 10.07 10.33
21-0056A
E
H
C
L
DIM PINS
e
A B D
A1
SSOP SHRINK SMALL OUTLINE PACKAGE
D D D D D
14 16 20 24 28
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.
12 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1995 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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