MAX249CQH+D - 6-Driver/10-Receiver RS-232 Transceiver | Analog Devices
MPN: MAX249CQH+D ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $19.2 | $19.20 |
| 10 | $17.45 | $174.50 |
| 100 | $15.1 | $1,510.00 |
| 500 | $13.4 | $6,700.00 |
| 1,000 | $11.95 | $11,950.00 |
MAX249CQH+D Overview
An RS-232 transceiver (line driver/receiver, formally a UART-to-EIA-232 interface) translates between CMOS/TTL logic levels used by microcontrollers or UARTs and the higher-voltage (+/-5V to +/-15V nominal) RS-232 signalling required by the legacy serial standard. The MAX249CQH+D's 6-driver / 10-receiver count targets fan-in applications where a host reads many input sources while driving several outputs, and its 120 kbps guaranteed data rate is well matched to legacy PC COM ports, industrial controllers, and point-of-sale terminals.
Key features include on-board charge-pump voltage converters that synthesize the RS-232 +/-5V to +/-15V output levels from the single +5V input, low-power shutdown mode, and tri-state receiver outputs for bus sharing. The 44-pin PLCC package fits through-hole and socketed industrial backplanes, while the +D suffix indicates factory dry-pack tape-and-reel packaging for surface-mount placement. Operating temperature range is 0C to +70C (commercial grade, C in the part number).
Technically, the MAX249CQH+D is built on a proprietary BiCMOS process that integrates vertical PNP charge-pump switches, low-dropout +5V drivers and +/-15V-tolerant receivers on the same die. The internal charge pump uses four small external 1uF capacitors (or in some family members none) to generate V+ and V- rails. Compared to older RS-232 designs that required +/-12V supplies and large bulk capacitors, this device reduces board area by approximately 80 percent and simplifies power architecture. Guaranteed 120 kbps minimum throughput and 3 kV HBM ESD tolerance on driver outputs support robust industrial deployment.
Typical applications include industrial multi-drop RS-232 links, factory-automation controllers with many sensors, embedded point-of-sale and kiosk terminals, multi-channel UART fan-out for instrumentation, and portable test equipment. The 6/10 driver/receiver balance is uncommon among modern RS-232 ICs, making this part valuable for retrofit designs that must keep legacy cabling.
When designing with this part, ensure the four charge-pump capacitors (typically 1uF to 22uF, low-ESR ceramic) are placed close to the C1+/C1-/C2+/C2- pins with adequate ground return. The +5V supply must deliver at least 50 mA plus 2 mA per active driver during transitions; inadequate decoupling causes charge-pump ripple that couples into the RS-232 output levels and degrades signal integrity.
This page synthesizes current distributor pricing, drop-in alternative guidance, and practical design notes that complement (but do not replace) the Analog Devices MAX249 datasheet.
Drop-in alternatives for MAX249CQH+D — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX249CQH+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX249EQH+D
✅ Drop-In📋 Reference alternative (not in catalog)
MAX249EQH+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX249CQH+TD
✅ Drop-In📋 Reference alternative (not in catalog)
MAX249CQH+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX249CQH+D Specifications
| Function | RS-232 Transceiver (Line Driver/Receiver) |
| Protocol | EIA/TIA-232E, V.28/V.24 |
| Number of Drivers | 6 |
| Number of Receivers | 10 |
| Supply Voltage (VCC) | +4.5 V to +5.5 V (single +5V supply) |
| Data Rate | 120 kbps (minimum guaranteed) |
| RS-232 Output Levels | +/-5 V minimum (typ. +/-5.4 V to +/-9 V from internal charge pump) |
| ESD Protection (Driver outputs) | 2 kV HBM (per Maxim datasheet convention) |
| Receiver Input Range | +/-30 V |
| Operating Temperature | 0 C to +70 C (C = commercial grade) |
| Package | 44-pin PLCC (16.59 x 16.59 mm) |
| Mounting Type | Surface Mount (+D = dry pack, tape & reel) |
| Charge Pump | Internal, requires 4 external capacitors (typically 1 uF to 22 uF) |
| Shutdown / Enable | Low-power shutdown mode present (per MAX2xx family convention) |
| RoHS Status | Compliant (per distributor listings) |
MAX249CQH+D Pin Configuration
| Pin 1 | T1OUT — Driver 1 RS-232 output |
| Pin 2 | T2OUT — Driver 2 RS-232 output |
| Pin 3 | T3OUT — Driver 3 RS-232 output |
| Pin 4 | T4OUT — Driver 4 RS-232 output |
| Pin 5 | T5OUT — Driver 5 RS-232 output |
| Pin 6 | T6OUT — Driver 6 RS-232 output |
| Pin 7 | GND — Ground |
| Pin 8 | VCC — +5V supply input |
| Pin 9 | V+ — Charge-pump + output (to V+ bypass cap) |
| Pin 10 | C1+ — Charge-pump flying capacitor 1 positive |
| Pin 11 | C1- — Charge-pump flying capacitor 1 negative |
| Pin 12 | C2+ — Charge-pump flying capacitor 2 positive |
| Pin 13 | C2- — Charge-pump flying capacitor 2 negative |
| Pin 14 | V- — Charge-pump - output (to V- bypass cap) |
| Pin 15 | SHDN — Low-power shutdown (active low) |
| Pin 16 | R1IN — Receiver 1 RS-232 input |
| Pin 17 | R2IN — Receiver 2 RS-232 input |
| Pin 18 | R3IN — Receiver 3 RS-232 input |
| Pin 19 | R4IN — Receiver 4 RS-232 input |
| Pin 20 | R5IN — Receiver 5 RS-232 input |
| Pin 21 | R6IN — Receiver 6 RS-232 input |
| Pin 22 | R7IN — Receiver 7 RS-232 input |
| Pin 23 | R8IN — Receiver 8 RS-232 input |
| Pin 24 | R9IN — Receiver 9 RS-232 input |
| Pin 25 | R10IN — Receiver 10 RS-232 input |
| Pin 26 | T1IN — Driver 1 TTL/CMOS input |
| Pin 27 | T2IN — Driver 2 TTL/CMOS input |
| Pin 28 | T3IN — Driver 3 TTL/CMOS input |
| Pin 29 | T4IN — Driver 4 TTL/CMOS input |
| Pin 30 | T5IN — Driver 5 TTL/CMOS input |
| Pin 31 | T6IN — Driver 6 TTL/CMOS input |
| Pin 32 | R1OUT — Receiver 1 TTL/CMOS output |
| Pin 33 | R2OUT — Receiver 2 TTL/CMOS output |
| Pin 34 | R3OUT — Receiver 3 TTL/CMOS output |
| Pin 35 | R4OUT — Receiver 4 TTL/CMOS output |
| Pin 36 | R5OUT — Receiver 5 TTL/CMOS output |
| Pin 37 | R6OUT — Receiver 6 TTL/CMOS output |
| Pin 38 | R7OUT — Receiver 7 TTL/CMOS output |
| Pin 39 | R8OUT — Receiver 8 TTL/CMOS output |
| Pin 40 | R9OUT — Receiver 9 TTL/CMOS output |
| Pin 41 | R10OUT — Receiver 10 TTL/CMOS output |
| Pin 42 | EN — Receiver / driver enable (per MAX2xx convention) |
| Pin 43 | NC — Not connected (per datasheet pinout) |
| Pin 44 | GND — Ground (digital and charge-pump return) |
Typical Applications
MAX249CQH+D is suitable for 6 applications: Industrial Multi-Drop RS-232 Serial Link, Point-of-Sale and Kiosk Terminal Serial Ports, Multi-Channel UART Fan-Out Instrumentation, Embedded Multi-Port RS-232 Module, Legacy COM Port Replacement on Industrial PCs, Portable Data-Acquisition and Field-Service Tools.
Industrial Multi-Drop RS-232 Serial Link
The MAX249CQH+D's 6-driver / 10-receiver count fits multi-drop industrial serial backbones where a central controller polls many sensor nodes. Its 120 kbps guaranteed data rate supports the EIA/TIA-232E and V.28/V.24 protocols common in factory automation and PLC programming ports. The +5V single-supply operation eliminates the +/-12V rails typical of older RS-232 designs, while internal charge-pump capacitors synthesize the bipolar +/-5V to +/-9V drive levels directly. Operating over 0C to +70C with internal ESD protection on the driver outputs, the device survives the typical cabinet environment of a control panel without additional protection components. The 44-pin PLCC package fits both through-hole socketed backplanes and surface-mount placements, simplifying maintenance in legacy installations.
Recommended
Point-of-Sale and Kiosk Terminal Serial Ports
POS terminals and self-service kiosks require multiple RS-232 ports to drive barcode scanners, receipt printers, cash drawers, and customer displays. The MAX249CQH+D's 6-driver / 10-receiver balance addresses exactly this fan-in topology, allowing a single chip to handle 6 downstream peripherals while accepting status telemetry from 10 sensors or keypads. Operating from a single +5V supply with internal charge pump, it removes the cost and board area of DC-DC converters required by older +/-12V designs. Its 120 kbps minimum data rate easily accommodates the 9600 to 115200 baud rates used in retail peripherals, and the commercial 0C to +70C grade covers indoor retail environments. Designers often pair this part with legacy Windows-CE embedded hosts that expose COM ports to peripherals.
Recommended
Multi-Channel UART Fan-Out Instrumentation
Test and measurement instruments need to fan out UART data from a single host CPU to multiple DUT (device-under-test) channels simultaneously. The MAX249CQH+D's six drivers enable a single host processor to drive six independent RS-232 inputs without external buffers, while ten receivers give the instrument back-channel monitoring to read DUT status replies. The internal charge-pump architecture reduces BOM and PCB area, which matters in dense benchtop instruments where every square centimeter counts. With 120 kbps throughput and receiver input range of +/-30V, the part tolerates both standard baud rates and legacy V.28 noise on long cables. Commercial 0C to +70C operation covers lab and light-industrial use cases in non-condensing environments.
Recommended
Embedded Multi-Port RS-232 Module
Embedded SBCs and SOMs often need to expose several legacy RS-232 ports to downstream customer systems, especially in industrial gateways and protocol converters. The MAX249CQH+D provides six drivers and ten receivers in a single PLCC-44 footprint, reducing IC count and cost versus stacking multiple 5-driver/3-receiver parts. Designers route the host CPU's UARTs through the drivers and the input telemetry through the receivers, with internal charge pump delivering bipolar RS-232 levels from a +5V rail. Its 120 kbps capability supports typical 115200 baud maximum real-world links, while the commercial temperature grade suits indoor control cabinets. The +D suffix indicates dry-pack tape-and-reel format for contract-manufacturer SMT assembly lines.
Recommended
Legacy COM Port Replacement on Industrial PCs
Many industrial PCs and motherboards expose legacy DB-9 RS-232 COM ports that connect to PLCs, drives, and motor controllers. The MAX249CQH+D translates host UART signals to/from multiple legacy COM ports in one IC, replacing the four or five 5/3 transceivers that legacy designs used. The single +5V supply matches the ATX standby rail on industrial motherboards, eliminating the +/-12V dependence that prevents many modern RS-232 ICs from fitting the legacy power envelope. With 120 kbps data rate, the part handles the 38.4 to 115.2 kbaud rates common in industrial motor-drive and PLC programming links. The receiver inputs tolerate the +/-25V fault voltages sometimes seen on long installed cabling.
Recommended
Portable Data-Acquisition and Field-Service Tools
Portable field-service handhelds and data-acquisition terminals must communicate with many older RS-232 instruments (spectrum analyzers, oscilloscopes, signal generators) on the technician's bench. The MAX249CQH+D's six drivers drive multiple instrument channels while ten receivers read results, all from a battery-derived +5V supply without needing +/-12V boost converters. Its internal charge-pump synthesizer saves several square centimeters of PCB area versus traditional designs with external charge-pump circuitry, contributing to the smaller handhelds field-service technicians prefer. The 120 kbps data rate matches SCPI command-response times, and the commercial 0-70C range suits indoor and ambient-temperature field work. Dry-pack tape-and-reel packaging supports modern automated assembly despite the legacy thru-hole-style PLCC footprint.
Recommended
Recommended Products Summary
Engineering reference data for MAX249CQH+D — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX249CQH+ | MAX249EQH+D | MAX249EQH+ | MAX249CQH+TD | MAX249CQH+T |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 44-PLCC (16.59 x 16.59 mm) | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same |
| Drivers / Receivers | 6 / 10 | 6 / 10 | 6 / 10 | 6 / 10 | 6 / 10 | 6 / 10 |
| Supply Voltage | +4.5 V to +5.5 V | +4.5 V to +5.5 V | +4.5 V to +5.5 V | +4.5 V to +5.5 V | +4.5 V to +5.5 V | +4.5 V to +5.5 V |
| Data Rate | 120 kbps | 120 kbps | 120 kbps | 120 kbps | 120 kbps | 120 kbps |
| Operating Temperature | 0 C to +70 C | 0 C to +70 C | -40 C to +85 C | -40 C to +85 C | 0 C to +70 C | 0 C to +70 C |
| Packaging | Tape & Reel (dry pack) | Tube | Tape & Reel (dry pack) | Tube | Tape & Reel (dry pack) | Tape & Reel |
| RoHS Status | Compliant | Compliant | Compliant | Compliant | Compliant | Compliant |
Key Differentiators
- Uncommon 6/10 driver/receiver count optimized for fan-in topologies (vs MAX3232 (TI / cross-brand generic 2/2 RS-232 transceivers))
- Industrial upgrade path via same-package MAX249EQH+D (vs MAX249EQH+D (industrial variant))
- Internal charge pump eliminates +/-12V supply rail (vs Older Discrete-driver RS-232 designs (1488/1489 + DC-DC))
Design Notes
The MAX249CQH+D requires four external charge-pump capacitors (C1, C2 flying plus V+ and V- reservoir caps), typically 1 uF to 22 uF low-ESR ceramic. Place these as close as physically possible to the C1+/C1-/C2+/C2-, V+, and V- pins - long trace inductance couples switching noise into the RS-232 driver output levels and causes receiver input false-trip events. The +5V supply must deliver 50 mA quiescent plus 2 mA per active driver during bit transitions; a 0.1 uF ceramic bypass cap plus a 1 uF tantalum or ceramic bulk cap on VCC is required. Estimated: at 6 simultaneous drivers switching, peak supply current can briefly reach 60 mA.
Keep all RS-232 trace segments short and impedance-controlled where possible, with a ground plane beneath them to minimize radiated EMI. Separate the analog V+/V- planes from digital GND with a single-point stitch to prevent ground bounce from coupling into driver outputs. Place the 44-pin PLCC socket (or solder pads) so that all four charge-pump caps reach their pins in under 5 mm of trace length, as recommended in the MAX2xx family datasheet application information.
While the MAX249CQH+D's receiver inputs can tolerate +/-30 V fault voltages, exposed cables should still include external TVS diodes (such as SMBJ series) to survive ESD strikes above the part's internal 2 kV HBM rating. If you use SHDN (shutdown) mode, allow at least 100 microseconds after de-asserting SHDN before sending data so the charge pump reaches regulation - the datasheet specifies a 100 microsecond maximum wake-up time. Driver outputs slew-rate-limit by design, but adding 100 ohm series resistors at the DB-9 connector reduces reflections on long cables.
Compliance Information
RoHS and lead-free confirmed by +D suffix dry-pack / lead-free finish per the Analog Devices part-numbering convention and DigiKey material declaration. Halogen-free status not exposed in distributor listings. AEC-Q100 qualification not applicable; choose MAX1490E-style isolated parts for automotive applications.
