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FEATURES 200 kB/s Transmission Rate Small (0.1 F) Charge Pump Capacitors Single 5 V Power Supply Meets All EIA-232-E and V.28 Specifications Two Drivers and Two Receivers On-Board DC-DC Converters 9 V Output Swing with +5 V Supply 30 V Receiver Input Levels Pin Compatible with MAX222/MAX232A/MAX242 APPLICATIONS Computers Peripherals Modems Printers Instruments GENERAL DESCRIPTION
High Speed, +5 V, 0.1 F CMOS RS-232 Drivers/Receivers ADM222/ADM232A/ADM242*
FUNCTIONAL BLOCK DIAGRAM
+5V INPUT 0.1F VCC 0.1F
C1+ 0.1F
+5V TO +10V V+ VOLTAGE DOUBLER C1- C2+ +5V TO -10V VOLTAGE INVERTER V- 0.1F
0.1F C2-
TTL/CMOS INPUTS*
T1IN T2IN R1OUT R2OUT
T1 T2 R1 R2
T1OUT T2OUT R1IN R2IN EN SHDN
RS-232 OUTPUTS
TTL/CMOS OUTPUTS
RS-232 INPUTS**
The ADM222, ADM232A, ADM242 are a family of high speed RS-232 line drivers/receivers offering transmission rates up to 200 kB/s. Operating from a single +5 V power supply, a highly efficient on-chip charge pump using small (0.1 F) external capacitors allows RS-232 bipolar levels to be developed. Two RS-232 drivers and two RS-232 receivers are provided on each device. The devices are fabricated on BiCMOS, an advanced mixed technology process which combines low power CMOS with high speed bipolar circuitry. This allows for transmission rates up to 200 kB/s yet minimizes the quiescent power supply current to under 5 mA. The ADM232A is a pin-compatible, high speed upgrade for the AD232 and for the ADM232L. It is available in 16-pin DIP and in both narrow and wide surface mount (SOIC) packages. The ADM222 contains an additional shutdown (SHDN) function which may be used to disable the device thereby reducing the supply current to 0.1 A. During shutdown, all transmit/ receive functions are disabled. The ADM222 is available in 18-pin DIP and in a wide surface mount (SOIC) package. The ADM242 combines both shutdown (SHDN) and enable (EN) functions. The shutdown function reduces the supply curent to 0.1 mA. During shutdown, the transmitters are disabled but the receivers continue to operate normally. The enable function allows the receiver outputs to be disabled thereby facilitating sharing a common bus. The ADM242 is available in 18-pin DIP and in a wide surface mount (SOIC) package.
*Protected by U.S. Patent No. 5,237,209.
ADM2xx
GND
(ADM242) (ADM222, ADM242)
* INTERNAL 400k PULL-UP RESISTOR
ON EACH TTL/MOS INPUT
** INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
ORDERING GUIDE
Model ADM222AN ADM222AR ADM232AAN ADM232AARN ADM232AARW ADM242AN ADM242AR
Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Option N-18 R-18W N-16 R-16N R-16W N-18 R-18W
REV. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703
(V = +5 10%, 0.1 F; specADM222/ADM232A/ADM242-SPECIFICATIONS ifications VT to T C1-C4 =otherwiseallnoted.) unless
CC MIN MAX
Parameter RS-232 TRANSMITTERS Output Voltage Swing Input Logic Threshold Low, VINL Input Logic Threshold High, VINH Logic Pullup Current Data Rate Output Resistance Output Short Circuit Current (Instantaneous) RS-232 RECEIVERS RS-232 Input Voltage Range RS-232 Input Threshold Low RS-232 Input Threshold High RS-232 Input Hysteresis RS-232 Input Resistance TTL/CMOS Output Voltage Low, VOL TTL/CMOS Output Voltage High, VOH TTL/CMOS Output Short-Circuit Current TTL/CMOS Output Short-Circuit Current TTL/CMOS Output Leakage Current EN Input Threshold Low, VINL EN Input Threshold High, VINH POWER SUPPLY Power Supply Current Shutdown Power Supply Current SHDN Input Leakage Current SHDN Input Threshold Low, VINL SHDN Input Threshold High, VINH AC CHARACTERISTICS Transition Region Slew Rate Transmitter Propagation Delay TTL to RS-232 Receiver Propagation Delay RS-232 to TTL Receiver Output Enable Time Receiver Output Disable Time Transmitter Output Enable Time Transmitter Output Disable Time Transmitter + to - Propagation Delay Difference Receiver + to - Propagation Delay Difference
Specifications subject to change without notice.
Min 5 2.0 200 300 7 -30 0.8 0.2 3 3.5 -2 10
Typ 9 1.4 1.4 5 22
Max
Units V
Test Conditions/Comments All Transmitter Outputs Loaded with 3 k to Ground TIN TIN TIN = 0 V VCC = V+ = V- = 0 V, VOUT = 2 V
0.8 40
V V A kB/s mA V V V V k V V mA mA A V V mA mA A A V V V/s s s s s ns ns s s ns ns
+30 1.3 1.8 0.5 5 0.2 2.4 1.0 7 0.4
VCC = 5 V IOUT = 3.2 mA IOUT = -1.0 mA Source Current (VOUT = GND) Sink Current (VOUT = VCC) SHDN = GND/EN = VCC 0 V VOUT VCC
-10 30 0.05 10 1.4 1.4 4 15 0.1 1.4 1.4 12 0.7 0.7 0.2 0.3 125 160 250 3.5 300 100 0.8
2.0
8 10 1 0.8
No Load 3 k Load on Both Outputs
2.0 6
30 3.5 3.5 0.5 0.5 500 500
CL = 50 pF to 2500 pF, R L = 3 k to 7 k Measured from +3 V to -3 V or -3 V to +3 V tPHLT tPLHT tPHLR tPLHR tER tDR SHDN Goes high SHDN Goes low
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ADM222/ADM232A/ADM242
ABSOLUTE MAXIMUM RATINGS * (TA = +25C unless otherwise noted)
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6 V V+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (VCC - 0.3 V) to +13 V V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V to -13 V Input Voltages TIN . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to (VCC + 0.3 V) R IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 V Output Voltages TOUT . . . . . . . . . . . . . . . . . . . . (V+, +0.3 V) to (V-, -0.3 V) ROUT . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to (VCC + 0.3 V) Short Circuit Duration TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous Power Dissipation N-16 . . . . . . . . . . . . . . . . . . . . . . . 400 mW (Derate 7.5 mW/C above +70C) JA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 80C/W Power Dissipation R-16N . . . . . . . . . . . . . . . . . . . . . 400 mW (Derate 7 mW/C above +70C) JA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 80C/W
Power Dissipation R-16W . . . . . . . . . . . . . . . . . . . . . 400 mW (Derate 7 mW/C above +70C) JA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 80C/W Power Dissipation N-18 . . . . . . . . . . . . . . . . . . . . . . . 400 mW (Derate 7 mW/C above +70C) JA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 80C/W Power Dissipation R-18W . . . . . . . . . . . . . . . . . . . . . 400 mW (Derate 7 mW/C above +70C) JA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 80C/W Operating Temperature Range Industrial (A Version) . . . . . . . . . . . . . . . . -40C to +85C Storage Temperature Range . . . . . . . . . . . . -65C to +150C Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . +300C Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215C Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220C
*This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
Test Circuits
+3V VIN
+3V VIN 0V
tPLHT
VOUT
tPHLT
V+ 0V V-
tPHLR
VOUT
tPLHR
VCC 50% GND
Figure 1. Transmitter Propagation Delay Timing
Figure 3. Receiver Propagation Delay Timing
+3V EN INPUT
EN INPUT
3V
0V
0V
tER
+3.5V RECEIVER OUTPUT +0.8V
VOL RECEIVER OUTPUT VOH
tDR
VOH -0.5V
VOL + 0.5V
Figure 2. Receiver Enable Timing
Figure 4. Receiver Disable Timing
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ADM222/ADM232A/ADM242
PIN FUNCTION DESCRIPTION
VIN SHDN 3k 50pF VOUT
Mnemonic VCC V+ V-
Function Power Supply Input, +5 V 10%. Internally generated positive supply (+10 V nominal). Internally generated negative supply (-10 V nominal). Ground Pin. Must be connected to 0 V. External capacitor 1, (+ terminal) is connected to this pin. External capacitor 1, (- terminal) is connected to this pin. External capacitor 2, (+ terminal) is connected to this pin. External capacitor 2, (- terminal) is connected to this pin. Transmitter (Driver) Inputs. These inputs accept TTL/CMOS levels. An internal 400 k pull-up resistor to VCC is connected on each input. Transmitter (Driver) Outputs. These are RS-232 levels (typically 9 V). Receiver Inputs. These inputs accept RS-232 signal levels. An internal 5 k pull-down resistor to GND is connected on each of these inputs. Receiver Outputs. These are TTL/CMOS levels. No Connect. No connections are required to this pin. (ADM242 Only) Active Low Digital Input. May be used to enable or disable (three-state) both receiver outputs. (ADM222 & ADM242) Active Low Digital Input. May be used to disable the device so that the power consumption is minimized. On the ADM222 all drivers and receivers are disabled. On the ADM242 the drivers are disabled but the receivers remain enabled.
Figure 5. Shutdown Test Circuit
GND C1+ C1- C2+
3V SHDN INPUT 0V
C2-
tDT
TIN
V+ + 5V
TOUT
TRANSMITTER OUTPUT - 5V V-
RIN
Figure 6. Transmitter Shutdown Disable Timing
ROUT NC EN
+5V INPUT C5 0.1F 6.3V 2 C1 0.1F 4 5 C2 0.1F 6 C1+ C1- C2+ C2- 15 T1 11 T2IN 13 R1OUT TTL/CMOS OUTPUTS 10 R2OUT R2 R1 9 R2IN 18 SHDN T2 14 R1IN RS-232 INPUTS** 8 T2OUT T1OUT RS-232 OUTPUTS
SHDN
17 VCC 3
C3 0.1F
+5V TO +10V V+ VOLTAGE DOUBLER +5V TO -10V VOLTAGE INVERTER V-
7 C4 0.1F
12 TTL/CMOS INPUTS* T1IN
NC C1+ V+ C1- C2+ C2- V- T2OUT R2IN
1 2 3 4 5 6 7 8 9
18 17 16
SHDN VCC GND T1OUT R1IN R1OUT T1IN T2IN R2OUT
ADM222
15
ADM222
GND 16
TOP VIEW 14 (Not to Scale) 13 12 11 10
* INTERNAL 400k PULL-UP RESISTOR
ON EACH TTL/MOS INPUT
** INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
NC = NO CONNECT
Figure 7. ADM222 Typical Operating Circuit
Figure 8. ADM222 DIP & SOIC Pin Configurations
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REV. 0
ADM222/ADM232A/ADM242
EN
C1+ V+ C1- C2+ C2- V- T2OUT R2IN 1 2 3 4 5 6 7 8 16 VCC 15 GND 14 T1OUT
1 2 3 4 5 6 7 8 9
18 SHDN 17 VCC
C1+ V+ C1- C2+ C2- V- T2OUT R2IN
16 GND
ADM232A
ADM242
15
T1OUT R1IN R1OUT
13
R1IN
TOP VIEW 12 R1OUT (Not to Scale) 11 T1IN 10 T2IN 9 R2OUT
TOP VIEW 14 (Not to Scale) 13
12 T1IN 11 T2IN 10 R2OUT
Figure 9. ADM232A DIP/SOIC Pin Configuration
Figure 11. ADM242 DIP/SOIC Pin Configuration
+5V INPUT C5 0.1F 6.3V 1 C1 0.1F 3 4 C2 0.1F 5 C1+ VCC 2 C3 0.1F
+5V INPUT C5 0.1F 6.3V 2 C1 0.1F 4 5
6 C4 0.1F 14 7 13 8
17 3 C3 0.1F
C1+
+5V TO +10V V+ C1-VOLTAGE DOUBLER C2+ +5V TO -10V V- VOLTAGE INVERTER C2-
VCC +5V TO +10V V+ VOLTAGE DOUBLER C1-
C2 0.1F
C2+
6
7 +5V TO -10V V- VOLTAGE INVERTER C2- 15
C4 0.1F
TTL/CMOS INPUTS*
T1IN T2IN R1OUT R2OUT
11 10 12 9
T1 T2 R1 R2
T1OUT T2OUT R1IN R2IN RS-232 OUTPUTS
TTL/CMOS INPUTS*
T1IN T2IN
12 11
T1 T2 R1 R2
T1OUT 8 T2OUT 14 9 18 R1IN R2IN SHDN RS-232 OUTPUTS
TTL/CMOS OUTPUTS
RS-232 INPUTS**
TTL/CMOS OUTPUTS*
R1OUT 13 R2OUT EN 10 1 GND
RS-232 INPUTS**
ADM232A
GND 15
ADM242
* INTERNAL 400k PULL-UP RESISTOR
ON EACH TTL/MOS INPUT
16
* INTERNAL 400k PULL-UP RESISTOR
ON EACH TTL/MOS INPUT
** INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
** INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
Figure 10. ADM232A Typical Operating Circuit
Figure 12. ADM242 Typical Operating Circuit
REV. 0
-5-
ADM222/ADM232A/ADM242-Typical Performance Characteristics
12 VCC = 5V TA = +25C 10 V+ | V- |
TOUT - V
12 VCC = 5V TA = +25C
10
V+, ( | V- | ) - V
8
8
TOUT HIGH
6
6
| TOUT LOW |
4
4
2
2
0 0
5 I+, ( | I- | ) - mA
10
15
0
0
2
4
6
8 IOUT - mA
10
12
14
Figure 13. Charge Pump V+, V- vs. Current
Figure 16. Transmitter Output Voltage vs. Current
9
TRANSMITTER OUTPUT VOLTAGE - V
8 7
20kB 60kB 120kB
100 90
A4
0.010V
6 200kB 5
4 3 VCC = +5V TA = +25C TX1 = +5V; TX2 = 0V - 5V SQUARE WAVE BOTH TX OUTPUTS LOADED WITH 3k//CL 2 0 1000 2000 3000 4000 LOAD CAPACITANCE - pF 400kB 500kB
10 0%
5V
5V
100s
Figure 14. Transmitter Baud Rate vs. Load Capacitance
Figure 17. Charge Pump V+, V- Exiting Shutdown
A2
100 90
2.4V
100 90
A1
-0.6 V
10 0%
10 0%
5V
5V
1s
5V
5V
1 s
Figure 15. Transmitter Unloaded Slew Rate
Figure 18. Transmitter Fully Loaded Slew Rate
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REV. 0
ADM222/ADM232A/ADM242
GENERAL INFORMATION
The ADM222/ADM232A/ADM242 are high speed RS-232 drivers/receivers requiring a single digital +5 V supply. The RS232 standard requires transmitters that will deliver 5 V minimum on the transmission channel and receivers that can accept signal levels down to 3 V. The parts achieve this by integrating step up voltage converters and level shifting transmitters and receivers onto the same chip. CMOS technology is used to keep the power dissipation to an absolute minimum. All devices contains an internal charge pump voltage doubler and a voltage inverter that generates 10 V from the +5 V input. Four external 0.1 F capacitors are required for the internal charge pump voltage converter. The ADM222/ADM232A/ADM242 is a modification, enhancement and improvement to the AD230-AD241 family and derivatives thereof. It is essentially plug-in compatible and does not have materially different applications.
CIRCUIT DESCRIPTION
As required by the RS-232 standard, the slew rate is limited to less than 30 V/s without the need for an external slew limiting capacitor, and the output impedance in the power-off state is greater than 300 .
Receiver Section
The receivers are inverting level shifters which accept RS-232 input levels ( 3 V to 15 V) and translate them into 5 V TTL/ CMOS levels. The inputs have internal 5 k pull-down resistors to ground and are also protected against overvoltages of up to 30 V. The guaranteed switching thresholds are 0.8 V minimum and 2.4 V maximum which are well within the 3 V RS232 requirement. The low level threshold is deliberately positive as it ensures that an unconnected input will be interpreted as a low level. The receivers have Schmitt trigger input with a hysteresis level of 0.5 V. This ensures error free-reception for both noisy inputs and for inputs with slow transition times
Enable and Shutdown Functions
The internal circuitry consists of four main sections. These are: A Charge Pump Voltage Converter TTL/CMOS to RS-232 Transmitters RS-232 to TTL/CMOS Receivers Enable and Shutdown Functions.
Charge Pump DC-DC Voltage Converter
On the ADM222, both receivers are fully disabled during shutdown. On the ADM242, both receivers continue to operate normally. This function is useful for monitoring activity so that when it occurs, the device can be taken out of the shutdown mode. The ADM242 also contains a receiver enable function (EN) which can be used to fully disable the receivers, independent of SHDN.
APPLICATIONS INFORMATION
The Charge Pump Voltage converter consists of an oscillator and a switching matrix. The converter generates a 10 V supply from the input 5 V level. This is done in two stages using a switched capacitor technique. The 5 V input supply is doubled to 10 V using capacitor C1 as the charge storage element. The -10 V level is also generated from the input 5 V supply using C1 and C2 as the storage elements. Capacitors C3 and C4 are used to reduce the output ripple. Their values are not critical and can be reduced if higher levels of ripple are acceptable. The charge pump capacitors C1 and C2 may also be reduced at the expense of higher output impedance on the V+ and V- supplies. The V+ and V- supplies may also be used to power external circuitry if the current requirements are small. Please refer to the typical performance characteristics which shows the V+, V- output voltage vs. current. In the shutdown mode the charge pump is disabled and V+ decays to VCC while V- decays to 0 V.
Transmitter (Driver) Section
A selection of typical operating circuits is shown in Figures 13 to 19.
A1
100 90
2.0V
10 0%
5V
5V
5S
Figure 19. Transmitter Output Disable Timing
The Drivers convert TTL/CMOS input levels into RS-232 output levels. With VCC = +5 V and driving a typical RS-232 load, the output voltage swing is 9 V. Even under worst case conditions the drivers are guaranteed to meet the 5 V RS-232 minimum requirement. The input threshold levels are both TTL and CMOS compatible with the switching threshold set at VCC /4. With a nominal VCC = 5 V the switching threshold is 1.25 V typical. Unused inputs may be left unconnected, as an internal 400 k pull- up resistor pulls them high forcing the outputs into a low state.
REV. 0
-7-
ADM222/ADM232A/ADM242
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
16-Pin Plastic DIP (N-16)
16-Lead Narrow SOIC (R-16N)
C1877-7.5-1/94
0- 8 0.0098 (0.25) 0.0040 (0.10) 0.0500 (1.27) 0.0192 (0.49) 0.0138 (0.35) BSC 0.0500 (1.27) 0.0160 (0.41)
0.0500 (1.27) 0.0157 (0.40)
16 PIN 1 1
9 0.280 (7.11) 0.240 (6.10) 8
16
9
0.2440 (6.20) 0.2284 (5.80) 0.1574 (4.00) 0.1497 (3.80)
1 0.840 (21.33) 0.745 (18.93) 0.210 (5.33) 0.060 (1.52) 0.015 (0.38) 0.325 (8.25) 0.300 (7.62) 0.195 (4.95) 0.115 (2.93)
8
0.3937 (10.00) 0.3859 (9.80)
0.0688 (1.75) 0.0532 (1.35)
0.0196 (0.50) 0.0099 (0.25)
0.200 (5.05) 0.125 (3.18) 0.022 (0.558) 0.014 (0.356)
0.150 (3.81)
0.015 (0.381) 0.008 (0.204)
0.100 (2.54) BSC
0.070 (1.77) 0.045 (1.15)
SEATING PLANE
0.0099 (0.25) 0.0075 (0.19)
16-Lead Wide SOIC (R-16W)
18-Lead Wide SOIC (R-18W)
16
9
18
10 0.2992 (7.60) 0.2914 (7.40) 0.4193 (10.65) 0.3937 (10.00)
0.299 (7.60)
0.419 (10.65)
1
8
PIN 1 1 9
0.413 (10.50) 0.012 (0.3) 0.104 (2.65) 0.05 (1.27) REF 0.019 (0.49)
0.030 (0.75)
0.4625 (11.75) 0.4469 (11.35) 0.1043 (2.65) 0.0926 (2.35)
0.0291 (0.74) x 45 0.0098 (0.25)
0.013 (0.32)
0.042 (1.07)
0.0118 (0.30) 0.0040 (0.10) 0.0500 (1.27) BSC 0.0192 (0.49) 0.0138 (0.35) 0.0125 (0.32) 0.0091 (0.23) 8 0
18-Pin Plastic DIP (N-18)
PIN 1 1 9
0.280 (7.11) 0.240 (6.10)
0.925 (23.49) 0.845 (21.47) 0.210 (5.33) MAX 0.160 (4.06) 0.115 (2.93) 0.022 (0.558) 0.014 (0.356) 0.100 (2.54) BSC 0.070 (1.77) 0.045 (1.15) 0.060 (1.52) 0.015 (0.38) 0.130 (3.30) MIN SEATING PLANE
0.325 (8.25) 0.300 (7.62) 0.195 (4.95) 0.115 (2.93) 0.015 (0.381) 0.008 (0.204)
-8-
REV. 0
PRINTED IN U.S.A.
18
10
ADM222/ADM232A/ADM242
ORDERING GUIDE
Model ADM222AN ADM222AR ADM232AAN ADM232AARN ADM232AARW ADM242AN ADM242AR
Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Option* N-18 R-18W N-16 R-16N R-16W N-18 R-18W
*For outline information see Package Information section.
REV. 0
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