ADM234LAR - 4/4 5V RS-232 Interface | Analog Devices
MPN: ADM234LAR ✓ ActiveADM234LAR Overview
An RS-232 interface IC is a transceiver within the broader interface-IC and data-communication semiconductor hierarchy. It converts low-voltage CMOS logic into RS-232-compatible line levels and converts incoming RS-232 signals back into CMOS logic. The ADM234LAR integrates this bidirectional conversion so a system can connect a UART, microcomputer, or embedded controller to a serial port without implementing discrete charge-pump and level-shifting circuits on the PCB.
Key features include a single 5 V power supply, 120 kB/s data rate, onboard DC-DC converters, approximately 9 V output swing from a 5 V supply, and support for 1 µF charge-pump capacitors. Low-power shutdown is also listed, while the receivers remain active during shutdown. A 30 V receiver-input rating provides additional tolerance for exposed serial connections.
The integrated DC-DC converter allows the drivers to generate the positive and negative voltage swings required by RS-232 without a negative supply rail. This simplifies system power architecture, although external charge-pump capacitor selection, layout, and ripple behavior remain important. The four-driver/four-receiver arrangement consolidates multiple serial channels in one package and can reduce board area when compared with separate single-channel transceivers.
Typical applications include industrial serial controllers, data-logging equipment, instrumentation, point-of-sale systems, embedded control panels, and legacy peripheral connectivity. The ADM234LAR is particularly useful where the host logic operates from 5 V but the external cable interface requires bipolar RS-232 levels. Designers must still account for cable length, common-mode voltage, ground noise, and protection requirements.
The principal layout consideration is keeping charge-pump and high-voltage driver paths compact while maintaining adequate separation from sensitive logic. Place the specified capacitors close to their associated pins, use a low-inductance ground return, and route protected connector-side traces away from clocks, analog inputs, and precision references. A solid ground plane and short return path help reduce RS-232 return-current effects.
This product page combines the verified ADM234LAR feature data with package guidance, application analysis, comparison criteria, and design notes. Because verified pricing, exact pin functions, operating-temperature limits, and several electrical limits were not included in the supplied records, those fields are marked for confirmation rather than inferred from unrelated parts.
Drop-in alternatives for ADM234LAR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
ADM232LAR
✅ Drop-In ⚠️ Specs UnverifiedContact for price
View Datasheet →ADM233LAR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADM236LAR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADM237LAR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADM238LAR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ADM234LAR Specifications
| Product Type | 5 V-powered CMOS RS-232 drivers/receivers |
| Supply Voltage | 5 V |
| Number of Drivers | 4 |
| Number of Receivers | 4 |
| Maximum Data Rate | 120 kB/s |
| RS-232 Compliance | EIA-232-E and V.28 specifications |
| Output Swing | 9 V from a 5 V supply |
| Charge-Pump Capacitor Value | 1 µF |
| Power-Supply Type | Single positive supply |
| DC-DC Converter | Onboard |
| Low-Power Shutdown | Supported |
| Receiver Status During Shutdown | Receivers remain active |
| Maximum Receiver Input Voltage | 30 V |
| Package | 20-lead SSOP |
| JEDEC Package Reference | MO-095AG |
ADM234LAR Pin Configuration
| Pin 1 | [DATA_NEEDED: pin 1 name] — Confirm against the official ADM234LAR package drawing |
| Pin 2 | [DATA_NEEDED: pin 2 name] — Confirm against the official ADM234LAR package drawing |
| Pin 3 | [DATA_NEEDED: pin 3 name] — Confirm against the official ADM234LAR package drawing |
| Pin 4 | [DATA_NEEDED: pin 4 name] — Confirm against the official ADM234LAR package drawing |
| Pin 5 | [DATA_NEEDED: pin 5 name] — Confirm against the official ADM234LAR package drawing |
| Pin 6 | [DATA_NEEDED: pin 6 name] — Confirm against the official ADM234LAR package drawing |
| Pin 7 | [DATA_NEEDED: pin 7 name] — Confirm against the official ADM234LAR package drawing |
| Pin 8 | [DATA_NEEDED: pin 8 name] — Confirm against the official ADM234LAR package drawing |
| Pin 9 | [DATA_NEEDED: pin 9 name] — Confirm against the official ADM234LAR package drawing |
| Pin 10 | [DATA_NEEDED: pin 10 name] — Confirm against the official ADM234LAR package drawing |
| Pin 11 | [DATA_NEEDED: pin 11 name] — Confirm against the official ADM234LAR package drawing |
| Pin 12 | [DATA_NEEDED: pin 12 name] — Confirm against the official ADM234LAR package drawing |
| Pin 13 | [DATA_NEEDED: pin 13 name] — Confirm against the official ADM234LAR package drawing |
| Pin 14 | [DATA_NEEDED: pin 14 name] — Confirm against the official ADM234LAR package drawing |
| Pin 15 | [DATA_NEEDED: pin 15 name] — Confirm against the official ADM234LAR package drawing |
| Pin 16 | [DATA_NEEDED: pin 16 name] — Confirm against the official ADM234LAR package drawing |
| Pin 17 | [DATA_NEEDED: pin 17 name] — Confirm against the official ADM234LAR package drawing |
| Pin 18 | [DATA_NEEDED: pin 18 name] — Confirm against the official ADM234LAR package drawing |
| Pin 19 | [DATA_NEEDED: pin 19 name] — Confirm against the official ADM234LAR package drawing |
| Pin 20 | [DATA_NEEDED: pin 20 name] — Confirm against the official ADM234LAR package drawing |
Typical Applications
ADM234LAR is suitable for 6 applications: Industrial Data-Logging Equipment, Embedded Control Panels, Point-of-Sale Terminals, Test and Measurement Instruments, Communication and Network Support Equipment, Legacy Peripheral Connectivity.
Industrial Data-Logging Equipment
The ADM234LAR fits industrial data-logging equipment that must collect RS-232 data from legacy meters, controllers, or laboratory instruments. Its four drivers and four receivers allow several ports to share one 20-lead SSOP footprint, while the onboard DC-DC converters derive the required bipolar RS-232 levels from a single 5 V supply. At rates up to 120 kB/s, the interface supports conventional instrument-control traffic without a separate negative rail. The main system consideration is protecting the exposed connector from industrial surges, because the verified 30 V receiver-input rating provides tolerance but does not replace a suitably rated protection network.
Recommended
Embedded Control Panels
The ADM234LAR is appropriate for embedded control panels where an MCU or module must connect to several RS-232 peripherals while retaining a 5 V-only power architecture. Four integrated drivers and four receivers reduce the number of separate interface packages and associated PCB area. The verified 120 kB/s maximum data rate is more than adequate for configuration links, status commands, and short control exchanges. Because shutdown leaves the receivers active, firmware can still interpret incoming remote-console traffic while local driver outputs are disabled, although the exact enable behavior must follow the manufacturer datasheet.
Recommended
Point-of-Sale Terminals
Retail point-of-sale terminals can use the ADM234LAR to interface a 5 V controller with RS-232 peripherals such as scales, receipt printers, or magnetic-card equipment. Consolidating four drivers and four receivers into one SSOP package simplifies routing when several legacy serial ports are needed. The single 5 V supply avoids generating a system-wide negative rail solely for RS-232 signaling, and the 120 kB/s rate supports typical transaction traffic. Cable routing and grounding remain important because peripheral power-supply noise can couple into the RS-232 interface through connected equipment.
Recommended
Test and Measurement Instruments
The ADM234LAR suits test and measurement instruments that need to connect a controller to RS-232-equipped analyzers, fixtures, or legacy laboratory peripherals. Its onboard DC-DC converters and 1 µF charge-pump capacitors reduce the external power-conversion burden, while the four-channel configuration supports several instrument links. The 120 kB/s rate is appropriate for command-and-response instrumentation rather than high-speed bulk transfers. Designers should keep converter-capacitor loops tight and preserve a low-impedance ground return so switching activity from the internal charge pump does not distort measurements sharing the same board.
Recommended
Communication and Network Support Equipment
The ADM234LAR can provide legacy console or management ports in communication equipment that already uses 5 V logic power. Four drivers and four receivers make it practical to support multiple RS-232 links without allocating a separate package to every port, and the active-during-shutdown receiver behavior can support partial power management. Its EIA-232-E and V.28 compatibility makes it suitable for established management protocols operating at up to 120 kB/s. In network-support products, the RS-232 connector should still have its own surge and ESD strategy because external cables can introduce hazards not represented by the IC's internal specifications.
Recommended
Legacy Peripheral Connectivity
The ADM234LAR is useful when modern 5 V logic must connect to legacy peripherals that expose only RS-232 ports. Its single-supply operation and integrated DC-DC converters reduce adaptation-board complexity, while the 4/4 channel arrangement supports several peripherals over one compact IC. The 9 V output swing is consistent with conventional RS-232 signaling, and the 120 kB/s rate accommodates many legacy control and printing interfaces. Firmware designers should verify driver shutdown polarity and receiver behavior, and hardware teams should confirm connector-side pin assignments against the official package drawing before fabrication.
Recommended
Recommended Products Summary
Engineering reference data for ADM234LAR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADM232LAR | ADM233LAR | ADM236LAR | ADM237LAR | ADM238LAR |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | SSOP-20 | SSOP-20 | SSOP-20 | SSOP-20 | SSOP-20 | SSOP-20 |
Key Differentiators
- Higher channel density than ADM233LAR (vs ADM233LAR)
- Single-supply RS-232 operation (vs ADM238LAR)
- Receiver availability during shutdown (vs ADM232LAR)
- 120 kB/s interface performance (vs ADM236LAR)
Design Notes
Place each required 1 µF charge-pump capacitor directly across its associated ADM234LAR pins, using the shortest possible traces and an uninterrupted ground connection. The onboard converter can generate switching ripple even though the external interface is RS-232. Keep these loops away from crystal circuits, analog inputs, and precision references, and avoid routing connector-side driver traces beneath sensitive circuitry. Follow the current Analog Devices recommended layout and capacitor-placement drawing when releasing production artwork.
RS-232 signaling is unbalanced, so ground current and cable noise can influence receiver thresholds. Connect the interface ground to the logic ground through a low-impedance path near the transceiver, and use a continuous ground plane under the device. Avoid long ground-return loops between the connector and IC. If the cable can exceed several metres or leave the enclosure, add appropriately rated surge and ESD protection at the connector and preserve isolation between protected and unprotected nets.
Decouple the 5 V supply locally with the capacitor network specified in the manufacturer datasheet and place it at the ADM234LAR power pins. The onboard DC-DC converter requires clean input voltage to generate a stable RS-232 output swing. Route the supply return through the same ground reference used by the charge-pump capacitors. Verify startup and shutdown behavior with the intended load because the receivers remain active during shutdown while the drivers can enter a low-power state.
Do not treat the 30 V receiver-input rating as a general-purpose surge rating. It indicates the receiver's stated input-voltage tolerance, not unlimited protection for the complete interface. Likewise, a matching SSOP package does not by itself prove that every same-family MPN is a functional drop-in. Before substituting ADM232LAR, ADM233LAR, ADM236LAR, ADM237LAR, or ADM238LAR, compare lead functions, channel counts, shutdown polarity, electrical limits, and PCB dimensions against the exact schematic revision.
Compliance Information
The supplied verified records do not provide component-level RoHS, REACH, lead-free, halogen-free, or conflict-minerals declarations. JEDEC package reference MO-095AG appears in the verified Analog Devices family datasheet snippet. The interface IC is not presented as an automotive-qualified AEC-Q100 product in the supplied data.
