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19-1751; Rev 0; 6/00
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers
General Description
The MAX3316-MAX3319 transceivers have a proprietary low-dropout transmitter output stage enabling RS-232compatible performance from +2.25V to +3.0V with a dual-charge pump. These devices require only four 0.1F capacitors, and are guaranteed to operate at data rates up to 460kbps. The MAX3318/MAX3319 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 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 MAX3318 is a 2-Tx/2-Rx device while the MAX3319 is a 1-Tx/1-Rx device. These devices also feature a logic-level output (READY) that asserts when the charge pump is regulating and the device is ready to begin transmitting. The MAX3316/MAX3317 are 2-Tx/2-Rx transceivers. The MAX3317 features a 1A shutdown mode that can be entered by driving SHDN low. The MAX3317's receivers remain active while in shutdown mode, allowing external devices such as modems to be monitored using only 1A supply current. These devices are available in space-saving packages: MAX3316 (16-pin SSOP and 20-pin TSSOP), MAX3317/ MAX3318 (20-pin SSOP and 20-pin TSSOP), and MAX3319 (16-pin SSOP).
Features
o AutoShutdown Plus (MAX3318/MAX3319) o 300A Operating Supply Current o 1A Low-Power Shutdown with Receivers Active o Guaranteed 460kbps Data Rate o Guaranteed 4V/s Slew Rate o RS-232 Compatible Down to 2.25V
MAX3316-MAX3319
Ordering Information
PART MAX3316CUP MAX3316CAE MAX3316EUP MAX3316EAE TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 20 TSSOP 16 SSOP 20 TSSOP 16 SSOP
Ordering Information continued at end of data sheet.
Typical Application Circuits
+2.5V CBYPASS C1 0.1F 0.1F 2 C1+ 4 C15 C2 0.1F CMOS INPUT CMOS OUTPUT 6 C2+ C2T1OUT 13 15 VCC V+ 3 C3 0.1F 7 C4 0.1F RS-232COMPATIBLE OUTPUT RS-232COMPATIBLE INPUT
MAX3319
V-
________________________Applications
Palmtop Computers Hand-Held Instruments Pagers Cellular Phones GPS Handy Terminals Hand-Held Electronic Books
AutoShutdown Plus is a trademark of Maxim Integrated Products. Pin Configurations appear at end of data sheet.
11 T1IN
9 R1OUT
R1IN 8 5k
1
READY
AutoShutdown Plus
INVALID 10
TO POWERMANAGEMENT UNIT VCC
12
FORCEON GND 14
FORCEOFF 16
Typical Application Circuits continued at end of data sheet.
Selector Guide
PART MAX3316 MAX3317 MAX3318 MAX3319 NO. OF DRIVERS/ RECEIVERS 2/2 2/2 2/2 1/1 GUARANTEED DATA RATE (kbps) 460 460 460 460 READY OUTPUT -- -- SHUTDOWN -- -- -- AutoShutdown Plus -- -- 1
________________________________________________________________ Maxim Integrated Products
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.
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V V+ to GND (Note 1) ..................................................-0.3V to +7V V- to GND (Note 1) ...................................................-7V to +0.3V V+ + |V-| (Note 1) .................................................................+13V Input Voltages T_IN, EN, SHDN, 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 SSOP (derate 8.00mW/C above +70C).........640mW 20-Pin TSSOP (derate 7.00mW/C above +70C).......559mW Operating Temperature Ranges MAX331_C_ _.....................................................0C to +70C MAX331_E_ _ ..................................................-40C to +85C Storage Temperature Range .............................-65C to +150C Die Temperature ..............................................................+150C 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
(V CC = +2.25V to +3.0V, C1-C4 = 0.1F, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V CC = +2.5V, TA = +25C.) PARAMETER SYMBOL CONDITIONS FORCEON = GND, FORCEOFF = VCC, all R_IN idle, all T_IN idle (MAX3318/MAX3319) SHDN = GND (MAX3317), FORCEOFF = GND (MAX3318/MAX3319) SHDN = VCC, no load (MAX3317), FORCEON = FORCEOFF = VCC, no load (MAX3318/MAX3319) T_IN, EN, SHDN, FORCEON, FORCEOFF T_IN, EN, SHDN, FORCEON, FORCEOFF T_IN, EN, SHDN, FORCEON, FORCEOFF EN = VCC (MAX3317), receivers disabled IOUT = 0.5mA IOUT = -0.5mA 0.9 VCC -25 TA = +25C TA = +25C TA = +25C All transmitter outputs loaded with 3k to ground 0.7 VCC 0.3 3 5 7 +25 0.3 VCC 0.7 VCC 0.3 0.01 0.05 1 10 0.1 VCC MIN TYP MAX UNITS DC CHARACTERISTICS (VCC = +2.5V, TA = +25C) AutoShutdown Plus Supply Current Shutdown Supply Current 1 10 A
1
10
A
Supply Current LOGIC INPUTS Input Logic Threshold Low Input Logic Threshold High Transmitter Input Hysteresis Input Leakage Current RECEIVER OUTPUTS Output Leakage Current Output Voltage Low Output Voltage High RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance TRANSMITTER OUTPUTS Output Voltage Swing
0.3
1
mA
0.3 VCC
V V V A A V V V V V V k
3.7
4
V
2
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers
ELECTRICAL CHARACTERISTICS (continued)
(V CC = +2.25V to +3.0V, C1-C4 = 0.1F, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V CC = +2.5V, TA = +25C.) PARAMETER Output Resistance Output Short-Circuit Current Output Leakage Current VCC = 0 or 2.25V to 3.0V, VOUT = 12V, transmitters disabled Positive threshold Negative threshold -2.7 -0.3 0.3 0.1 VCC 0.9 VCC 1 30 100 15 30 60 SYMBOL CONDITIONS VCC = 0, transmitter output = 2V MIN 300 TYP 10M 25 60 25 MAX UNITS mA A
MAX3316-MAX3319
AutoShutdown Plus (FORCEON = GND, FORCEOFF = VCC) (MAX3318/MAX3319) Receiver Input Threshold to INVALID Output High Receiver Input Threshold to INVALID Output Low INVALID, READY Output Voltage Low INVALID, READY 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 Receiver or Transmitter Edge to Transmitters Shutdown tINVH tINVL tWU tAUTOSHDN
Figure 4a Figure 4a IOUT = 0.5mA IOUT = -0.5mA Figure 4b Figure 4b Figure 4b (Note 2)
2.7
V V V V s s s s
VCC = 2.5V, Figure 4b (Note 2)
TIMING CHARACTERISTICS
(V CC = +2.25V to +3.0V, C1-C4 = 0.1F, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V CC = +2.5V, 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 SYMBOL CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching R_IN to R_OUT, CL = 150pF Normal operation (MAX3317) Normal operation (MAX3317) |tPHL - tPLH| (Note 3) MIN 460 0.175 0.175 250 250 100 50 TYP MAX UNITS kbps s ns ns ns ns
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
TIMING CHARACTERISTICS (continued)
(V CC = +2.25V to +3.0V, C1-C4 = 0.1F, T A = T MIN to T MAX, unless otherwise noted. Typical values are at V CC = +2.5V, TA = +25C.) PARAMETER SYMBOL CONDITIONS VCC = 2.5V, TA = +25C, RL = 3k to 7k, one transmitter switching, measured from +3V to -3V or -3V to +3V, CL = 150pF to 2500pF MIN TYP MAX UNITS
Transition-Region Slew Rate
4
30
V/s
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 crosspoints.
Typical Operating Characteristics
(VCC = +2.5V, C1-C4 = 0.1F, 460kbps data rate, all transmitters loaded with 3k, TA = +25C, unless otherwise noted.)
MAX3316/MAX3317 TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
T_OUT+ TRANSMITTER OUTPUT VOLTAGE (V) 4 2 0 -2 -4 -6 3.45 3.65 2.25 2.45 2.65 2.85 3.05 3.25 3.45 3.65 VCC (V) T_OUTT1 TRANSMITTING AT 460kbps T2 TRANSMITTING AT 20kbps CL = 1000pF
MAX3316 TOC02
MAX3316/MAX3317 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX3316 TOC01
10 460kbps 230kbps 6
6
8 SUPPLY CURRENT (mA)
4
20kbps T1 TRANSMITTING AT SPECIFIED DATA RATE T2 TRANSMITTING AT 20kbps CL = 1000pF 2.25 2.45 2.65 2.85 3.05 3.25 VCC (V)
2
0
MAX3316/MAX3317 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3316 TOC03
MAX3316/MAX3317 SLEW RATE vs. LOAD CAPACITANCE
FOR DATA RATES UP TO 460kbps -SLEW
MAX3316 TOC04
5 TRANSMITTER OUTPUT VOLTAGE (V) 4 3 2 1 0 -1 -2 -3 -4 -5 0 1000 2000 T_OUTT_OUT+ T1 TRANSMITTING AT 460kbps T2 TRANSMITTING AT 20kbps
10
8 SLEW RATE (V/s)
6 +SLEW 4
2
0 3000 0 1000 2000 3000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF)
4
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers
Typical Operating Characteristics (continued)
(VCC = +2.5V, C1-C4 = 0.1F, 460kbps data rate, all transmitters loaded with 3k, TA = +25C, unless otherwise noted.)
MAX3316-MAX3319
MAX3316/MAX3317 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
MAX3316 TOC05
MAX3318/MAX3319 SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX3316 TOC06
MAX3318/MAX3319 TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
TRANSMITTER OUTPUT VOLTAGE (V) T_OUT+ 4 2 0 -2 -4 -6 T_OUTT1 TRANSMITTING AT 460kbps T2 TRANSMITTING AT 20kbps CL = 1000pF
MAX3316 TOC07
35 30 SUPPLY CURRENT (mA) 25
T1 TRANSMITTING AT SPECIFIED DATA RATE T2 TRANSMITTING AT 20kbps
15 460kbps 12 SUPPLY CURRENT (mA) 230kbps 9 20kbps
6
460kbps 20 15 10 5 0 0 1000 2000 LOAD CAPACITANCE (pF) 3000 20kbps 230kbps
6
3
0
T1 TRANSMITTING AT SPECIFIED DATA RATE T2 TRANSMITTING AT 20kbps CL = 1000pF 2.25 2.45 2.65 2.85 3.05 3.25 3.45 3.65
2.25
2.45
2.65
2.85
3.05
3.25
3.45
3.65
VCC (V)
VCC (V)
MAX3318/MAX3319 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3316 TOC08
MAX3318/MAX3319 SLEW RATE vs. LOAD CAPACITANCE
MAX3316 TOC09
MAX3318/MAX3319 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
T1 TRANSMITTING AT SPECIFIED DATA RATE T2 TRANSMITTING AT 20kbps 460kbps 20 230kbps 15 10 5 20kbps
MAX3316 TOC10
5 TRANSMITTER OUTPUT VOLTAGE (V) 4 3 2 1 0 -1 -2 -3 -4 -5 0 1000 2000 T_OUTT1 TRANSMITTING AT 460kbps T2 TRANSMITTING AT 20kbps T_OUT+
10
35 30 SUPPLY CURRENT (mA) 25
8 SLEW RATE (V/s)
-SLEW
6
+SLEW
4
2 FOR DATA RATES UP TO 460kbps 0 1000 2000 3000
0 3000 LOAD CAPACITANCE (pF)
0 0 1000 2000 LOAD CAPACITANCE (pF) 3000
LOAD CAPACITANCE (pF)
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
Typical Operating Characteristics (continued)
(VCC = +2.5V, C1-C4 = 0.1F, 460kbps data rate, all transmitters loaded with 3k, TA = +25C, unless otherwise noted.)
TRANSMITTER SKEW vs. LOAD CAPACITANCE (tPLH - tPHL)
T1 TRANSMITTING AT 460kbps T2 TRANSMITTING AT 20kbps
MAX3316E TOC11
MAX3318/MAX3319 READY TURN-ON TIME vs. TEMPERATURE
MAX3316E TOC12
MAX3318/MAX3319 READY TURN-OFF TIME vs. TEMPERATURE
MAX3316E TOC13
500
30 25 READY TURN-ON TIME (s) 20 15 10 5 0
200
READY TURN-OFF TIME (ns)
TRANSMITTER SKEW (ns)
400
160
300 MAX3316/MAX3317 200 MAX3318/MAX3319
120
80
100
40
0 0 500 1000 1500 2000 2500 3000 LOAD CAPACITANCE (pF)
0 -40 -20 0 20 40 60 80 -40 -20 0 20 40 60 80 TEMPERATURE (C) TEMPERATURE (C)
Pin Description
PIN MAX3316 SSOP 1 2 3 4 5 6 7, 14 8, 13 9, 12 10, 11 15 16 -- -- TSSOP 2 3 4 5 6 7 8, 17 9, 16 12, 15 13, 14 18 19 -- 1, 10, 11, 20 MAX3317 SSOP/ TSSOP 2 3 4 5 6 7 8, 17 9, 16 10, 15 12, 13 18 19 1 11, 14 MAX3318 SSOP/ TSSOP 2 3 4 5 6 7 8, 17 9, 16 10, 15 12, 13 18 19 -- -- MAX3319 SSOP 2 3 4 5 6 7 13 8 9 11 14 15 -- -- NAME FUNCTION
C1+ V+ C1C2+ C2VT_OUT R_IN R_OUT T_IN GND VCC EN N.C.
Positive Terminal of Voltage-Doubler ChargePump Capacitor +2 VCC Generated by the Charge Pump Negative Terminal of Voltage-Doubler ChargePump Capacitor Positive Terminal of Inverting Charge-Pump Capacitor Negative Terminal of Inverting Charge-Pump Capacitor -2 VCC Generated by the Charge Pump RS-232 Transmitter Outputs RS-232 Receiver Inputs CMOS Receiver Outputs CMOS Transmitter Inputs Ground +2.25V to +3.0V Single-Supply Voltage Receiver Enable, Active Low No Connection
6
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers
Pin Description (continued)
PIN MAX3316 SSOP -- -- TSSOP -- -- MAX3317 SSOP/ TSSOP 20 -- MAX3318 SSOP/ TSSOP -- 1 MAX3319 SSOP -- 1 NAME FUNCTION
MAX3316-MAX3319
SHDN READY
Shutdown Control, Active Low Ready to Transmit Output, Active High. READY is enabled high when V- goes below -2.75V and the device is ready to transmit. Valid Signal Detector Output, Active Low. A logic high indicates that a valid RS-232 level is present on a receiver input. Force-On Input, Active High. Drive high to override AutoShutdown Plus, keeping transmitters and receivers on (FORCEOFF must be high) (Table 1). Force-Off Input, Active Low. Drive low to shut down transmitters, receivers, and charge pump. This overrides AutoShutdown Plus and FORCEON (Table 1).
--
--
--
11
10
INVALID
--
--
--
14
12
FORCEON
--
--
--
20
16
FORCEOFF
Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3316-MAX3319s' internal power supply consists of a regulated dual charge pump that provides output voltages of +4.4V (doubling charge pump) and -4.3V (inverting charge pump), over the +2.25V to +3.0V input voltage range. The charge pump operates in discontinuous mode: if the output voltages are less than 4.4V, the charge pump is enabled; if the output voltages exceed 4.4V, 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 (MAX3318/MAX3319) is low when the charge pumps are disabled in shutdown mode. The READY signal asserts high when V- goes below -2.75V.
are turned off (high impedance) when FORCEOFF is asserted low, or when the AutoShutdown Plus circuitry senses that all receiver and transmitter inputs are inactive for more than 30 seconds. The transmitter outputs can be driven to 12V when power is off. The transmitter inputs do not have internal pullup resistors. Connect unused inputs to GND or VCC. Figure 1a shows an RS-232-compatibility circuit and Figure 1b shows MAX3316-MAX3319 transmitter output compatibility with an RS-232 receiver.
RS-232 Receivers
The MAX3316-MAX3319s' receivers convert RS-232 signal levels into CMOS-logic output levels. The receivers are rated to receive signals up to 25V. The MAX3316/MAX3318/MAX3319s' receivers feature inverting outputs that always remain active (Table 1). The MAX3317's receivers have inverting, three-state outputs. In shutdown, the receivers can be active or inactive (Table 2). The MAX3318/MAX3319 feature an INVALID output that is asserted low when no valid RS-232 voltage levels have been detected on all receiver inputs. Because INVALID indicates the receiver's input condition, it is independent of the states of FORCEON and FORCEOFF.
RS-232-Compatible Transmitters
The MAX3316-MAX3319s' transmitters are inverting level translators that convert CMOS-logic levels to RS-232-compatible voltage levels. They guarantee a 460kbps data rate with worst-case loads of 3k in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLinkTM). The MAX3317's transmitters are turned off (high impedance) when SHDN is asserted low, putting the device in shutdown mode. The MAX3318/MAX3319s' transmitters
LapLink is a trademark of Traveling Software.
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7
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
Table 1. Output Control Truth Table (MAX3318/MAX3319)
OPERATION STATUS 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 = Don't care *INVALID connected to FORCEON **INVALID connected to FORCEON and FORCEOFF FORCEON FORCEOFF RECEIVER OR VALID RECEIVER TRANSMITTER LEVEL EDGE WITHIN 30s X X X X Yes X No Yes No X X Yes No X Yes No X X T_OUT R_OUT
X 1 0 0 INVALID* INVALID* INVALID* INVALID** INVALID**
0 1 1 1 1 1 1 INVALID** INVALID**
High-Z Active Active High-Z Active Active High-Z Active High-Z
Active Active Active Active Active Active Active Active Active
MAX3318/MAX3319 AutoShutdown Plus Mode
Maxim's AutoShutdown Plus feature on the MAX3318/ MAX3319 allows the supply current to fall to 1A. These devices will enter the AutoShutdown Plus mode if FORCEOFF is high, FORCEON is low, and they do not sense a valid signal transition on any receiver or transmitter input for 30 seconds. This may occur if the RS-232 cable is disconnected or if the 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. Figure 4a depicts 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 Table 1 summarize the operating modes of the MAX3318/MAX3319. 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 edge received.
Table 2. Shutdown and Enable Control Truth Table (MAX3317)
SHDN 0 0 1 1 EN 0 1 0 1 T_OUT High-Z High-Z Active Active R_OUT Active High-Z Active High-Z
MAX3317 Shutdown Mode
Supply current falls to less than 1A in shutdown mode (SHDN = low). When shut down, the device's charge pumps are turned off, V+ is pulled down to VCC, V- is pulled to ground, and the transmitter outputs are disabled (high impedance). The time required to exit shutdown is typically 30s, as shown in Figure 2. Connect SHDN to VCC if the shutdown mode is not used; SHDN has no effect on R_OUT.
8
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
+2.5V CBYPASS 0.1F
VCC C1+ C1 0.1F C1C2+ C2 0.1F C2V+ C3 0.1F
MAX3316 MAX3317 MAX3318 MAX3319
V-
C4 0.1F
+5V
T_ IN
T_ OUT CL 1000pF
RX RS-232COMPLIANT TRANSCEIVER
R_ OUT
R_ IN
TX
GND
Figure 1a. RS-232-Compatibility Circuit
VCC OR SHDN (MAX3317) 5V/div T1 IN MAX3316-MAX3319 2V/div T1 5V/div T1 OUT MAX3316-MAX3319 2V/div T2 RS-232-COMPLIANT RECEIVER OUTPUT 5V/div FORCEOFF (MAX3318/MAX3319)
10s/div
Figure 1b. MAX3316-MAX3319 Transmitter Output Compatibility with an RS-232 Receiver
Figure 2. Transmitter Outputs when Exiting Shutdown or Powering Up
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9
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
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 is driven low. The time required to exit shutdown is typically 30s (Figure 2). By connecting FORCEON to INVALID, the MAX3318/ MAX3319 shut down when no valid receiver level is detected and wake up when a valid receiver level is detected. A 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 MAX3318/MAX3319 is awake. If the other system outputs valid RS-232 signal transitions within that time, the RS-232 ports on both systems remain enabled.
+0.3V
R_IN
-0.3V
30s TIMER R
INVALID
INVALID ASSERTED IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30s.
Figure 3a. INVALID Functional Diagram, INVALID Low
+2.7V
Connecting to the PC (MAX3318/MAX3319)
If direct software control is desired, use INVALID to indicate DTR or ring indicator (RI) signal. This can be used to connect a hand-held device to a PC. One example is using the hot sync function on a personal digital assistant (PDA). The transmitter and receiver signals (T_OUT and R_IN) are used for communication, while INVALID causes a change of state on RI. The change of state on RI will trigger an interrupt on the PC and allow communication to begin between the device and the PC. This eliminates the need for the PC to poll constantly the receiver or transmitter lines to determine if the device is connected.
R_IN
-2.7V
30s TIMER R
INVALID
INVALID DEASSERTED IF ANY RECEIVER INPUT HAS BEEN BETWEEN +2.7V AND -2.7V FOR LESS THAN 30s.
Figure 3b. INVALID Functional Diagram, INVALID High
INVALID HIGH +2.7V RECEIVER INPUT LEVELS INDETERMINATE +0.3V 0 -0.3V INDETERMINATE -2.7V INVALID HIGH
Applications Information
RS-232-Compatible Operation
The MAX3316-MAX3319 do not meet EIA-232 requirements for transmitter output voltage levels. EIA-232 compliance specifies transmitter output voltage swings of 5V when loaded with 3k and 2500pF. The receiver inputs are fully EIA-232 compliant. The MAX3316-MAX3319 will function properly with most modern RS-232 interfaces. This allows RS-232-compatible communication in low-voltage systems without the added expense of a voltage tripler or switched-mode power supply.
INVALID LOW
Figure 4a. Receiver Positive/Negative Thresholds for INVALID
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. 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
10
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
RECEIVER INPUTS
} REGION
INVALID
TRANSMITTER INPUTS
TRANSMITTER OUTPUTS VCC 0 READY *VCC OUTPUT 0 V+ VCC 0 V*MAX3318/MAX3319
INVALID OUTPUT
tINVL
tINVH tAUTOSHDN tWU
tAUTOSHDN tWU
Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram
C2, C3, C4, and CBYPASS to maintain proper ratios (C1 to other capacitors).
POWERMANAGEMENT UNIT MASTER SHDN LINE 0.1F 1M
FORCEOFF FORCEON
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 higher nominal value. The capacitor's equivalent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-.
MAX3318 MAX3319
Power-Supply Decoupling
In most circumstances, a 0.1F bypass capacitor is adequate. In applications that are sensitive to powersupply noise, decouple VCC to ground with a capacitor of the same value as charge pump capacitor C1. Connect bypass capacitors as close to the IC as possible.
Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a Mouse or Another System
Transmitter Outputs when Exiting Shutdown
Figure 2 shows two transmitter outputs when exiting shutdown mode. As they become active, the two transmitter outputs are shown going to opposite RS-232compatible levels (one transmitter input is high, the other is low). Each transmitter is loaded with 3k in par11
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2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
allel with 2500pF. The transmitter outputs display no ringing or undesirable transients as they come out of shutdown. Note that the transmitters are enabled only when the magnitude of V- exceeds approximately -3V.
2V/div T1 IN
High Data Rates
The MAX3316-MAX3319 maintain RS-232-compatible 3.7V minimum transmitter output voltage even at high data rates. Figure 6 shows a transmitter loopback test circuit. Figure 7 shows a loopback test result at 230kbps. For Figure 7, all transmitters were driven simultaneously at 230kbps into EIA/TIA-562 loads in parallel with 1000pF.
5V/div T1 OUT
R1 OUT 2V/div
Figure 7. Loopback Test Result at 230kbps
VCC CBYPASS VCC C1+ C1 C1C2+ C2 C2V+ C3*
Ordering Information (continued)
PART MAX3317CUP MAX3317CAP MAX3317EUP
VC4
TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C -40C to +85C
PIN-PACKAGE 20 TSSOP 20 SSOP 20 TSSOP 20 SSOP 20 TSSOP 20 SSOP 20 TSSOP 20 SSOP 16 SSOP 16 SSOP
MAX3316 MAX3317 MAX3318 MAX3319
MAX3317EAP MAX3318CUP MAX3318CAP MAX3318EUP MAX3318EAP MAX3319CAE
T_ IN
T_ OUT
R_ OUT
R_ IN 5k CL 1000pF
MAX3319EAE
FORCEON** VCC FORCEOFF**
Chip Information
GND
TRANSISTOR COUNT: 1130 PROCESS: CMOS
*C3 CAN BE RETURNED TO VCC OR GND. **MAX3318/MAX3319
Figure 6. Loopback Test Circuit
12
______________________________________________________________________________________
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
Pin Configurations (continued)
TOP VIEW
READY 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8 R2IN 9 R2OUT 10
20 FORCEOFF 19 VCC 18 GND 17 T1OUT
C1+ 1 V+ 2 C1- 3 C2+ 4 C2- 5 V- 6 T2OUT 7 R2IN 8
16 VCC 15 GND 14 T1OUT
N.C. 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8 R2IN 9 N.C. 10
20 N.C. 19 VCC 18 GND 17 T1OUT
MAX3316
13 R1IN 12 R1OUT 11 T1IN 10 T2IN 9 R2OUT
MAX3318
16 R1IN 15 R1OUT 14 FORCEON 13 T1IN 12 T2IN 11 INVALID
MAX3316
16 R1IN 15 R1OUT 14 T1IN 13 T2IN 12 R2OUT 11 N.C.
SSOP
SSOP/TSSOP
TSSOP
EN 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8 R2IN 9 R2OUT 10
20 SHDN 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
MAX3319
13 T1OUT 12 FORCEON 11 T1IN 10 INVALID 9 R1OUT
MAX3317
16 R1IN 15 R1OUT 14 N.C. 13 T1IN 12 T2IN 11 N.C.
SSOP
SSOP/TSSOP
______________________________________________________________________________________
13
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
Typical Application Circuits (continued)
+2.5V 0.1F C1 0.1F 2 C1+ 4 5 C2 0.1F 6 C119 VCC V+ 3 C3* 0.1F 0.1F 0.1F
+2.5V 16 1 C1+ 3 4 C4 0.1F 0.1F 5 C1C2+ C2T1OUT 14 RS-232COMPATIBLE OUTPUTS VCC V+ 2 C3* 0.1F 6 C4 0.1F
MAX3317
C2+ C2V-
7
MAX3316
V-
13 T1IN CMOS INPUTS 12 T2IN
T1OUT 17 RS-232COMPATIBLE OUTPUTS CMOS INPUTS
11 T1IN
T2OUT 8
10 T2IN
T2OUT 7
15 R1OUT CMOS OUTPUTS 10 R2OUT 1 EN GND 18
R1IN 16 5k R2IN 9 5k SHDN 20 RS-232COMPATIBLE INPUTS CMOS OUTPUTS
12 R1OUT
R1IN 13 5k RS-232COMPATIBLE INPUTS
9 R2OUT
R2IN 8 5k
GND 15 CIRCUIT SHOWN IS FOR THE 16-PIN SSOP.
*C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
14
______________________________________________________________________________________
2.5V, 1A, 460kbps, RS-232-Compatible Transceivers MAX3316-MAX3319
Typical Application Circuits (continued)
+2.5V CBYPASS C1 0.1F 0.1F 2 C1+ 4 5 C2 0.1F 6 C1C2+ C2T1OUT 17 RS-232-COMPATIBLE OUTPUTS 19 VCC V+ 3 C3 0.1F 7 C4 0.1F
MAX3318
V-
13 T1IN CMOS INPUTS
12 T2IN
T2OUT 8
15 R1OUT CMOS OUTPUTS 10 R2OUT
R1IN 16 5k R2IN 9 5k TO POWERMANAGEMENT UNIT VCC RS-232-COMPATIBLE INPUTS
1
READY
AutoShutdown Plus
INVALID 11
14
FORCEON GND 18
FORCEOFF 20
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________15 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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