The XC6123E535MR-G from Torex Semiconductor Ltd is a single-channel voltage supervisor IC designed to monitor system power integrity and provide watchdog functionality in embedded applications. This SOT-25-5 packaged device offers a fixed 3.5V threshold with open drain output topology, enabling flexible interfacing across various logic families and microcontroller reset architectures.
Configured as a watchdog circuit supervisor, the XC6123E535MR-G continuously monitors a single supply rail and asserts an active-low reset signal when the monitored voltage falls below the 3.5V threshold or when the watchdog timer expires. The 400ms typical reset timeout provides sufficient delay for power supply stabilization during startup and brown-out recovery, allowing processors and peripherals to achieve stable operating conditions before releasing from reset. The open drain output structure permits wired-OR configurations with other supervisory circuits and supports pull-up to voltage rails different from the monitored supply, accommodating mixed-voltage system designs common in battery-powered and industrial equipment.
The SC-74A surface mount package (SOT-753 equivalent) delivers a compact 2.9mm × 2.8mm footprint suitable for space-constrained layouts in portable devices, IoT sensors, and consumer electronics. Operating across the industrial temperature range of -40°C to 85°C, this supervisor maintains consistent threshold accuracy and timing performance in automotive peripherals, outdoor instrumentation, and HVAC control modules. MSL 1 rating eliminates floor life restrictions during assembly, streamlining manufacturing workflows for high-volume production environments.
As part of the XC6123 family, this variant integrates Torex's proprietary CMOS voltage detection circuitry to achieve low quiescent current consumption, extending battery runtime in energy-harvesting wireless sensors and always-on monitoring applications. The watchdog function detects software lockups and peripheral malfunctions by requiring periodic service pulses, automatically triggering system reset when firmware execution stalls—a fundamental safeguard for unattended remote equipment and medical devices where manual intervention is impractical.
The device's active-low reset polarity directly interfaces with the majority of ARM Cortex-M, RISC-V, and 8-bit microcontroller reset pins without additional inversion logic. Open collector output capability supports direct connection to level-shifting circuits or optocouplers for isolated reset distribution in multi-rail systems. ROHS3 compliant construction and REACH unaffected status ensure regulatory alignment for EU and global markets, while EAR99 classification facilitates straightforward export documentation for international distribution channels.
Typical deployment scenarios include embedded controllers requiring brown-out protection below 3.6V nominal supplies, battery-powered devices transitioning between active and sleep modes, and microprocessor systems demanding reliable startup sequencing. The 3.5V threshold suits LDO post-regulator monitoring in 3.3V systems where early warning of impending undervoltage conditions enables orderly data logging or graceful shutdown before logic corruption occurs. Available in tape and reel packaging with 1040 pieces of new original stock, the XC6123E535MR-G supports both prototype development and production procurement for designs requiring proven voltage supervision with minimal external component count.
XC6123E535MR-G (1)
Replacing the Torex Semiconductor XC6123E535MR-G Supervisor IC Without Creating Reset or Watchdog Timing Risk
When the Torex Semiconductor Ltd XC6123E535MR-G is unavailable, at end-of-life risk in a local supply chain, or being reviewed for second-source qualification, the replacement decision cannot be based only on package size or threshold voltage. This device combines supply-voltage monitoring, watchdog supervision, an active-low reset output, and an open-drain/open-collector output stage in a SOT-25-5 package. A substitute must therefore be checked against reset timing, watchdog behavior, output topology, threshold tolerance, startup sequencing, PCB pinout, and firmware watchdog servicing assumptions.
Commonly evaluated equivalent or alternative part numbers include:
- Torex Semiconductor Ltd XC6123E535MR-G
- Torex Semiconductor Ltd XC6123E535MR
- Microchip Technology MCP1316MT-35LE/OT
- Nisshinbo Micro Devices
R3112N351A-TR-FE
R3112N351A-TR-FE
Nisshinbo Micro Devices Inc.
IC SUPERVISOR 1 CHANNEL SOT23-5
98179
- Texas Instruments
TPS3823-33DBVR
TPS3823-33DBVR
Texas Instruments
IC SUPERVISOR 1 CHANNEL SOT23-5
200000
- Analog Devices
MAX823SEUK+T
MAX823SEUK+T
Analog Devices Inc./Maxim Integrated
IC SUPERVISOR 1 CHANNEL SOT23-5
50400
The closest replacement path is normally another XC6123E535MR-G device or the same Torex XC6123E535MR ordering code when the environmental suffix and packaging requirements are confirmed. Other supervisor IC alternatives can be valid, but they usually require review of watchdog timeout, reset delay, pin compatibility, threshold level, and output-drive behavior before being used as a drop-in replacement.
What the Torex Semiconductor XC6123E535MR-G Does in a Power-Supervision Circuit
The Torex Semiconductor XC6123E535MR-G is a single-channel PMIC supervisor IC with watchdog functionality. It monitors one supply rail with a 3.5 V threshold and asserts an active-low reset when the monitored voltage falls below the detection level or when watchdog servicing conditions are not satisfied. The output is open drain/open collector, allowing the reset line to be pulled up to a compatible logic voltage and shared with other reset sources if the board design supports wired-OR behavior.
| Key specification | XC6123E535MR-G engineering relevance |
|---|---|
| Manufacturer | Torex Semiconductor Ltd |
| Function | Watchdog circuit with voltage supervision |
| Monitored voltages | 1 channel |
| Voltage threshold | 3.5 V |
| Reset output | Active low |
| Output type | Open drain/open collector |
| Reset timeout | 400 ms typical |
| Package | SC-74A / SOT-753, supplier package SOT-25-5 |
| Mounting | Surface mount |
| Operating temperature | -40°C to +85°C |
| Packaging | Tape & Reel |
| Compliance | RoHS3 compliant, REACH unaffected, MSL 1 |
The 3.5 V threshold suggests use in systems where the reset point must be above a standard 3.3 V operating minimum or where the monitored rail is closer to a 5 V domain with a higher undervoltage margin. This matters when comparing alternatives: many popular watchdog supervisor ICs are available with 2.93 V, 3.08 V, 4.38 V, or 4.63 V thresholds, but not always with 3.5 V detection.
The 400 ms typical reset timeout affects power-up sequencing. If a replacement releases reset too early, a microcontroller, FPGA, communication IC, or memory subsystem may begin execution before oscillators, regulators, or peripheral rails have stabilized. If the delay is much longer, system boot time and watchdog recovery behavior may change.
The open-drain/open-collector output is also part of the compatibility decision. A push-pull reset alternative may not be safe on a shared reset node or on a reset line pulled up to a different voltage. For replacement work, the reset output stage, pull-up resistor value, leakage current, and reset low-voltage level should be reviewed along with the nominal threshold.
Typical applications include microcontroller reset supervision, embedded control boards, industrial modules, consumer electronics, battery-powered systems with watchdog recovery, and compact power-management designs where SOT-25-5 footprint efficiency is useful.
Candidate Replacement Parts for the Torex Semiconductor XC6123E535MR-G Supervisor IC
The following table compares practical replacement candidates. Some are closer functional equivalents, while others are alternative supervisor ICs that may require PCB, firmware, or timing validation.
| Manufacturer | Part Number | Key Specifications | Product Features | Typical Applications | Why It Can Replace the Original Part | Main Differences or Limitations | Recommended Usage |
|---|---|---|---|---|---|---|---|
| Torex Semiconductor Ltd | XC6123E535MR-G | 3.5 V threshold, watchdog supervisor, active-low reset, open-drain/open-collector output, 400 ms typical reset timeout, SOT-25-5 | Original device; single voltage monitor with watchdog; RoHS3 compliant | Existing designs using XC6123 series reset and watchdog timing | Exact original reference; maintains electrical, timing, and package assumptions | Availability and lead time may vary | First choice for production continuity and lowest redesign risk |
| Torex Semiconductor Ltd | XC6123E535MR | Same XC6123 base configuration when ordering suffix and compliance details match | Same functional family and expected same core behavior | Boards already qualified with XC6123E535MR-G | Can be treated as a near-equivalent if suffix, reel format, RoHS/green status, and datasheet revision are confirmed | Ordering code differences may indicate packaging or environmental suffix differences; must verify supplier documentation | Suitable when the “-G” suffix is not required by the approved vendor list or is covered by manufacturer documentation |
| Microchip Technology | MCP1316MT-35LE/OT | 3.5 V supervisor option, watchdog function, active-low reset option, SOT-23-5 class package | Voltage supervisor with watchdog timer; compact package | Microcontroller reset and watchdog monitoring in embedded systems | Similar monitored threshold class and watchdog-supervisor function | Pinout, reset delay, watchdog timeout, and output type must be compared against XC6123E535MR-G; not assumed pin-to-pin | Good candidate when a 3.5 V threshold is required and PCB/firmware validation is acceptable |
| Nisshinbo Micro Devices |
R3112N351A-TR-FE
Nisshinbo Micro Devices Inc.
IC SUPERVISOR 1 CHANNEL SOT23-5
98179
| 3.5 V-class voltage detector with watchdog function, N-channel open-drain style reset option, small SMD package | Supervisor/watchdog IC family for CPU monitoring | Industrial controllers, consumer electronics, compact MCU boards | Similar functional concept: voltage detection plus watchdog and open-drain reset behavior | Exact package outline, pin assignment, delay timing, and watchdog timing may differ | Useful for designs prioritizing open-drain reset behavior and similar threshold level |
| Texas Instruments |
TPS3823-33DBVR
Texas Instruments
IC SUPERVISOR 1 CHANNEL SOT23-5
200000
| 3.3 V rail supervisor family, watchdog input, active-low reset, SOT-23-5 package | Processor supervisory circuit with watchdog | MCU, DSP, and logic reset supervision | Provides watchdog reset supervision in a compact SMD package | Threshold is generally aligned to 3.3 V supervision rather than 3.5 V; reset delay and output behavior differ | Suitable when the monitored rail strategy can accept a lower reset threshold and board-level timing is requalified |
| Analog Devices |
MAX823SEUK+T
Analog Devices Inc./Maxim Integrated
IC SUPERVISOR 1 CHANNEL SOT23-5
50400
| Microprocessor supervisor with watchdog input, manual reset support, active-low reset, SOT-23-5 | Widely used watchdog supervisor family | Processor reset, watchdog recovery, portable and embedded electronics | Provides watchdog-based reset supervision and compact package availability | Threshold options differ from 3.5 V; output topology and reset timing may not match XC6123E535MR-G | Best for redesigns where watchdog supervision is needed but the voltage threshold can be changed intentionally |
The Microchip MCP1316MT-35LE/OT is often one of the more relevant functional alternatives because it can be selected in a 3.5 V threshold version. However, it still requires pinout and timing confirmation before replacing the Torex XC6123E535MR-G. Matching the threshold alone does not guarantee equivalent watchdog recovery behavior.
The Nisshinbo
R3112N351A-TR-FE
is another practical candidate where open-drain reset behavior and a 3.5 V-class detection level are desired. It should be evaluated carefully for watchdog timeout, reset release delay, and footprint differences.
R3112N351A-TR-FE
Nisshinbo Micro Devices Inc.
IC SUPERVISOR 1 CHANNEL SOT23-5
98179
The Texas Instruments
TPS3823-33DBVR
and Analog Devices
TPS3823-33DBVR
Texas Instruments
IC SUPERVISOR 1 CHANNEL SOT23-5
200000
MAX823SEUK+T
are stronger redesign alternatives than direct drop-in equivalents. They may be attractive where sourcing diversity, established supervisor families, or broader distributor availability matter, but their threshold and timing differences can change system behavior.
MAX823SEUK+T
Analog Devices Inc./Maxim Integrated
IC SUPERVISOR 1 CHANNEL SOT23-5
50400
Engineering Trade-Off Comparison for XC6123E535MR-G Replacement Selection
Replacement selection should separate “functional alternative” from “drop-in equivalent.” A part can provide voltage supervision and watchdog reset while still being unsuitable for an unchanged PCB or unchanged firmware watchdog interval.
| Evaluation factor | XC6123E535MR-G | XC6123E535MR | MCP1316MT-35LE/OT | R3112N351A-TR-FE | TPS3823-33DBVR | MAX823SEUK+T |
|---|---|---|---|---|---|---|
| Electrical compatibility | Baseline: 3.5 V threshold, open-drain/open-collector, active-low reset | Expected closest match if suffix requirements are verified | Good threshold alignment; output and timing must be checked | Good functional alignment if selected open-drain variant matches | Watchdog compatible concept, but threshold usually lower than 3.5 V | Watchdog compatible concept, but threshold differs from original |
| Mechanical compatibility | SOT-25-5 / SC-74A / SOT-753 | Likely same package family | SOT-23-5 class; footprint may differ | Small SMD package; pinout must be checked | SOT-23-5; not automatically same footprint | SOT-23-5; not automatically same footprint |
| Reset timing impact | 400 ms typical reset timeout | Expected same if same configuration | May differ; verify reset delay and watchdog timeout | May differ; verify delay timing | Common reset delay differs from Torex timing | Reset delay differs by family/version |
| Watchdog behavior | Original firmware timing reference | Expected same if same configuration | Requires firmware watchdog service interval review | Requires firmware watchdog interval review | Requires firmware review; watchdog timeout may be longer or shorter | Requires firmware review; watchdog timing differs |
| Output-stage risk | Open drain/open collector supports pull-up flexibility | Expected same | Must verify open-drain or push-pull variant | Open-drain variant can be suitable | Must confirm reset output type | Often push-pull style depending variant; shared reset line must be checked |
| Reliability and qualification | Already defined by original BOM | Low qualification burden if documentation matches | Requires component-level and system reset testing | Requires component-level and system reset testing | Requires broader validation due to threshold difference | Requires broader validation due to threshold difference |
| Package availability | Original inventory dependent | May improve sourcing if acceptable ordering code | Broad supplier ecosystem | Useful second-source path in some regions | Broad availability from TI channels | Broad availability from Analog Devices channels |
| Cost considerations | Depends on original stock and lead time | Similar to original family | May be competitive depending volume | Regionally variable | Often competitive in high-volume MCU designs | May be higher depending availability |
| Best-fit scenario | Existing approved design | Same design with suffix/order-code confirmation | Replacement where 3.5 V threshold must be preserved but validation is allowed | Replacement where open-drain reset and 3.5 V-class detection are preferred | Redesign where a lower 3.3 V reset threshold is acceptable | Redesign where watchdog supervisor function is needed and threshold changes are acceptable |
| Main limitation | Supply availability | Documentation confirmation needed | Not guaranteed pin-compatible | Not guaranteed pin-compatible | Threshold mismatch versus 3.5 V original | Threshold mismatch versus 3.5 V original |
For a no-layout-change replacement, the Torex Semiconductor XC6123E535MR-G remains the reference choice, followed by XC6123E535MR only after confirming suffix meaning, reel format, compliance status, and manufacturer ordering documentation.
For a controlled second-source qualification, MCP1316MT-35LE/OT and
R3112N351A-TR-FE
deserve closer review because they can align more closely with the 3.5 V detection requirement. The main work is not the nominal threshold comparison, but verification of reset output topology, watchdog timing, startup delay, pin assignment, and the behavior of the reset line during brownout and recovery.
R3112N351A-TR-FE
Nisshinbo Micro Devices Inc.
IC SUPERVISOR 1 CHANNEL SOT23-5
98179
For redesigns,
TPS3823-33DBVR
and
TPS3823-33DBVR
Texas Instruments
IC SUPERVISOR 1 CHANNEL SOT23-5
200000
MAX823SEUK+T
may be practical watchdog supervisor alternatives, especially when sourcing flexibility matters. Their use should be based on an intentional change to the reset threshold and timing model rather than an assumption of direct equivalence.
MAX823SEUK+T
Analog Devices Inc./Maxim Integrated
IC SUPERVISOR 1 CHANNEL SOT23-5
50400
Before approving any XC6123E535MR-G alternative, compare the latest manufacturer datasheets, confirm the PCB footprint and pinout, simulate or bench-test reset timing across supply ramp rates, and verify firmware watchdog servicing margins. For quotations and sourcing support for XC6123E535MR-G replacement parts, request pricing through IC-Components.com or email Info@IC-Components.com.
