Alternatives to Texas Instruments RI-STU-251B-01
Texas Instruments RI-STU-251B-01 and its qualified second sources, compared on form/fit/function, stock, lifecycle and price — the same checks Parter runs inside a BOM.
 RI-STU-251B-01Texas Instruments |  RI-STU-MRD2Texas Instruments | RI-SMD-MRD2Texas Instruments | |
|---|---|---|---|
| FFF Compatibility | The S251B is a large standalone industrial sub-assembly (200mm x 120mm x 120mm) with terminal blocks, whereas this is a 30-pin DIL micro-module.Requires a completely new physical mounting scheme, custom enclosure, and external wiring adapter.Supports the identical 134.2 kHz HDX protocol, but operates at a lower voltage (2.7V to 5.5V vs 10V to 15V) and outputs TTL/USB rather than native RS232/RS422/RS485. | This is a surface-mount module (SMD) requiring a custom land pattern on a PCB, unlike the original large chassis-mounted reader.Ultra-compact SMD format compared to the large 200mm x 120mm x 120mm standalone metal/plastic enclosure.Matches the 134.2 kHz frequency and LF HDX/FSK RF specifications but operates on 2.7V to 5.5V and lacks onboard high-voltage industrial serial transceivers. | |
 AI Summary | RI-STU-251B-01 by Texas Instruments: RFID Reader Module 134.2kHz. | The RI-STU-MRD2 is the official active low-frequency micro-reader module from Texas Instruments, supporting the same 134.2 kHz HDX transponders. While functionally compatible at the RF and protocol levels, it requires external level translators for industrial RS-232/422/485 serial communication and a local voltage regulator to match the original system's power rails.
| The RI-SMD-MRD2 is the surface-mount variant of TI's active micro-reader family, offering identical electrical and firmware performance to the RI-STU-MRD2. It is highly suited for modern designs where the reader is integrated directly onto a main controller PCB, but necessitates a complete board and system redesign.
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| Lifecycle Status | Obsolete | Active | Unknown |
| Market Availability | Discontinued | In stock | Unknown |
| REACH | REACH | REACH | Unknown |
| RoHS | RoHS | RoHS | Unknown |
| Description | RFID Reader Module 134.2kHz | RFID Reader Module 134.2kHz Module | The RI-SMD-MRD2 is the surface-mount variant of TI's active micro-reader family, offering identical electrical and firmware performance to t |
| Manufacturer | Texas Instruments | Texas Instruments | Texas Instruments |
| Type | RFID Reader Modules | RFID Reader Modules | Component |
| Datasheet | Open | Open | N/A |
| Lead Time | Unknown | 26 weeks | Unknown |
| Country of Origin | - | - | - |
| Export Control Class Number | EAR99 | EAR99 | EAR99 |
| HTSUS Code | 8543.70.9860 | - | - |
| Moisture Sensitivity Level | 1 (Unlimited) | - | - |
| Type | Read/Write | - | - |
| Frequency | 134.2kHz | - | - |
| Interface | RS 232, RS 422, RS 485 | - | - |
| Standards | ISO 11785 | - | - |
| Package / Case | 200mm x 120mm x 120mm, RS232, RS422/485 | - | - |
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Related parts
| Part | Market availability | Lifecycle | Alternatives available |
|---|---|---|---|
 RI-STU-MRD2Texas Instruments | In stock | Active | 2Alternatives availableSee Alternatives |
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Frequently asked questions
Yes. The Texas Instruments RI-STU-251B-01 is marked obsolete, so the manufacturer has discontinued it and any remaining supply is limited to distributor stock. The qualified second sources on this page are active parts you can design in today.
The closest qualified second sources for the Texas Instruments RI-STU-251B-01 are the RI-STU-MRD2 (Texas Instruments) and the RI-SMD-MRD2 (Texas Instruments). Each is compared against the original on fit, form and function in the table above.
Not always. The alternatives to the RI-STU-251B-01 are matched on function but can differ in package, pinout or a key parameter, so review the fit/form/function notes in the table and the datasheet before designing one in.
The RI-STU-251B-01 (Texas Instruments) is a part in the RFID Reader Modules category. This page lists qualified, cross-referenced replacements for it with a side-by-side comparison.
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