High-Speed, 5 V, 0.1 F CMOS RS-232 Drivers/Receivers
ADM222/ADM232A/ADM242
FEATURES FUNCTIONAL BLOCK DIAGRAM
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
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 µF) 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 that combines low power CMOS with highspeed 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-lead DIP and in both
narrow and wide surface-mount (SOIC) packages.
The ADM222 contains an additional shutdown (SHDN) function that may
be used to disable the device, thereby reducing the supply current
to 0.1 µA. During shutdown, all transmit/receive functions are
disabled. The ADM222 is available in 18-lead 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 current 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-lead DIP and in a wide surface-mount
(SOIC) package.
ADM222/ADM232A/ADM242–SPECIFICATIONS
(VCC = 5 V 10%. C1–C4 = 0.1 F; all specifications TMIN to TMAX unless
otherwise noted.)
| Parameter Min Typ Max Unit Test Conditions/Comments |
RS-232 TRANSMITTERS Output Voltage Swing ±5 ±9 V All Transmitter Outputs Loaded with 3 kΩ to Ground Input Logic Threshold Low, VINL 1.7 0.8 V TIN Input Logic Threshold High, VINH 2.4 1.7 V TIN Logic Pull-Up Current 12 40 µA TIN = 0 V Data Rate 200 kB/s Output Resistance 300 Ω VCC = V+ = V– = 0 V, VOUT = ±2 V Output Short Circuit Current (Instantaneous) ±10 mA |
RS-232 RECEIVERS RS-232 Input Voltage Range –30 +30 V RS-232 Input Threshold Low 0.8 1.2 V RS-232 Input Threshold High 1.6 2.4 V RS-232 Input Hysteresis 0.2 0.4 1.0 V VCC = 5 V RS-232 Input Resistance 3 5 7 kΩ TA = 0°C to 85°C TTL/CMOS Output Voltage Low, VOL 0.05 0.4 V IOUT = 3.2 mA TTL/CMOS Output Voltage High, VOH 3.5 V IOUT = –1.0 mA TTL/CMOS Output Short-Circuit Current –2 –85 mA Source Current (VOUT = GND)* TTL/CMOS Output Short-Circuit Current 10 35 mA Sink Current (VOUT = VCC)* TTL/CMOS Output Leakage Current ±0.05 ±10 µA SHDN = GND/EN = VCC 0 V ≤ VOUT ≤ VCC EN Input Threshold Low, VINL 1.4 0.8 V EN Input Threshold High, VINH 2.0 1.4 V |
POWER SUPPLY Power Supply Current 4 8 mA No Load 13 mA 3 kΩ Load on Both Outputs Shutdown Power Supply Current 0.1 10 µA SHDN Input Leakage Current ±1 µA SHDN Input Threshold Low, VINL 1.4 0.8 V SHDN Input Threshold High, VINH 2.0 1.4 V |
AC CHARACTERISTICS Transition Region Slew Rate 3 8 30 V/µs CL = 50 pF to 1000 pF, RL = 3 kΩ to 7 kΩ Measured from +3 V to –3 V or –3 V to +3 V Transmitter Propagation Delay TTL to RS-232 0.85 3.5 µs tPHLT 1.0 3.5 µs tPLHT Receiver Propagation Delay RS-232 to TTL 0.1 0.5 µs tPHLR 0.3 0.5 µs tPLHR Receiver Output Enable Time 125 500 ns tER Receiver Output Disable Time 160 500 ns tDR Transmitter Output Enable Time 250 µs SHDN Goes High Transmitter Output Disable Time 3.5 µs SHDN Goes Low Transmitter + to – Propagation Delay Difference 150 ns Receiver + to – Propagation Delay Difference 200 ns |
*Guaranteed by design, not production tested.
Specifications subject to change without notice.
Test Circuits
