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Renesas M51945AFP#DF1J
- Part No.:
- M51945AFP#DF1J
- Manufacturer:
- Renesas
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
M51945AFP#DF1J.pdf
- Description:
- VOLTAGE DETECTING, SYSTEM RESETT
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
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Product details
Overview
M51945AFP#DF1J from Renesas Electronics is an L-type (active-low) voltage-detecting system reset IC with externally adjustable detection threshold, 1.25 V internal reference, 2–17 V supply range, and 5-pin SIP package. It provides reliable power-on reset for microcomputers and logic circuits in industrial control and battery-powered systems where supply voltage monitoring and configurable reset assertion are required.
For engineers reviewing the M51945AFP#DF1J datasheet, M51945AFP#DF1J pinout, M51945AFP#DF1J application, or M51945AFP#DF1J equivalent, key selection considerations include its 1.25 V precision reference, ±15 mV hysteresis, 280 µA typical circuit current at 5 V, open-collector output configuration, and compatibility with external resistor-based voltage setting for custom reset thresholds between 2 V and 15 V.
Technical Context
The M51945AFP#DF1J implements a comparator-based reset architecture with a stable 1.25 V bandgap reference and 25 µA internal bias current. Its input stage monitors an external voltage divider network, while the output stage delivers active-low reset pulses via an open-collector transistor capable of sinking up to 4 mA.
It operates across –30°C to +85°C ambient temperature and supports both shared- and independent-power-supply configurations. The device features built-in hysteresis (9–23 mV) to prevent chatter during supply ramp-up/down and maintains functional operation down to 0.55 V supply voltage (VOPL), enabling ultra-low-voltage brownout detection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Detection Voltage | 1.25 V (typical); sets precise reset threshold via external R1/R2 divider |
| Hysteresis Voltage | 15 mV (typical); prevents false resets during slow or noisy supply transitions |
| Supply Voltage Range | 2 V to 17 V; supports wide-input industrial and battery-backed systems |
| Circuit Current | 280 µA (typical at VCC = 5 V); enables low-quiescent-power system monitoring |
| Output Type | Open-collector; allows flexible pull-up to any compatible rail (up to 17 V) |
| Propagation Delay | 4 µs (tPHL), 2 µs (tPLH); ensures fast response to supply faults without excessive delay |
| Operating Temperature | –30°C to +85°C; qualified for industrial-grade embedded applications |
Pinout & Package
Package: 5-pin SIP (SIP5-P-240-2.54 / 5P5T), plastic, lead-free Cu alloy leads, 11.9 mm × 2.54 mm footprint, 0.22 g mass.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Ground reference for internal circuitry and output sink path |
| 2 | Input | Voltage sense node connected to external R1/R2 divider; referenced to 1.25 V internal reference |
| 3 | Power-supply | VCC input (2–17 V); powers internal comparator and bias circuitry |
| 4 | Output | Open-collector NPN output; sinks current when reset asserted (low state) |
| 5 | NC | No connection; internally unconnected; must be left floating or tied to GND |
Key Features
| Feature | Design Value |
|---|---|
| Externally adjustable detection voltage | Settable from 2 V to 15 V using two external resistors (R1, R2); eliminates need for multiple fixed-threshold parts |
| Low operating supply voltage | Functional down to 0.55 V (VOPL); enables brownout detection in deeply discharged battery scenarios |
| Wide supply range | 2–17 V operation; accommodates 3.3 V, 5 V, 12 V, and 15 V systems without level-shifting |
| Open-collector output | Supports mixed-voltage interface (e.g., 3.3 V logic controlling 5 V or 12 V reset line) via external pull-up |
| Integrated hysteresis | 9–23 mV (ΔVS); suppresses noise-induced reset toggling without external components |
Applications
| Industrial Microcontroller Reset | Battery Voltage Monitoring |
|---|---|
|
Use Scenario: Power-on and brownout reset for 8/16-bit MCUs in programmable logic controllers and sensor nodes. IC Role / Device Role / Timing Role: Active-low reset generator triggered when VCC drops below user-defined threshold (e.g., 4.5 V). Use Value: Ensures deterministic MCU initialization and prevents erratic execution during unstable supply conditions. |
Use Scenario: End-of-life detection in portable medical devices powered by Li-ion or alkaline cells. IC Role / Device Role / Timing Role: Threshold comparator asserting reset when cell voltage falls below safe operating level (e.g., 2.8 V). Use Value: Prevents data corruption and unsafe operation by disabling system before critical undervoltage occurs. |
| DC/DC Converter Supervision | Logic Circuit Power Sequencing |
|
Use Scenario: Monitoring output rail of isolated DC/DC converters in telecom power modules. IC Role / Device Role / Timing Role: Secondary-side reset supervisor verifying regulated output stability before enabling downstream loads. Use Value: Adds fault containment layer that isolates downstream circuitry if converter fails or sags. |
Use Scenario: Coordinating power-up sequence between FPGA, memory, and analog subsystems on a single PCB. IC Role / Device Role / Timing Role: Generates synchronized reset pulse after all rails reach regulation, using shared VCC or independent sensing. Use Value: Eliminates race conditions and metastability by enforcing strict power sequencing without discrete timing RC networks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-detecting reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV803DBZQ1 | Fixed 3.08 V threshold; SOT-23-3 package; automotive AEC-Q100 qualified | Lacks external adjustability; suited for automotive infotainment but not field-configurable systems | Select when fixed threshold and automotive qualification outweigh configurability needs |
| MAX809TRD3+T | Fixed 3.08 V threshold; SOT-23-3; 1.2 µA quiescent current; no hysteresis adjustment | Lower IQ enables multi-year battery life; unsuitable for variable-threshold designs | Prefer for ultra-low-power, fixed-threshold applications where board space and current budget are critical |
Compared with M51945AFP#DF1J, TLV803DBZQ1 offers automotive reliability but sacrifices voltage configurability, while MAX809TRD3+T reduces supply current by >200× yet locks detection to a single value-making M51945AFP#DF1J the only choice when field-adjustable reset thresholds across 2–15 V are required in industrial environments.
Availability
M51945AFP#DF1J is available at Aetrix Electronics and suitable for industrial automation, battery management systems, and DC/DC converter supervision requiring stable component supply and long-term design continuity.
Supply support for M51945AFP#DF1J includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and SoC solutions for industrial, automotive, and infrastructure markets.
The M51945AFP#DF1J belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series, designed specifically for cost-sensitive, high-reliability reset supervision in non-automotive industrial equipment where external threshold tuning is essential.
FAQ
What is the detection voltage accuracy of the M51945AFP#DF1J?
The M51945AFP#DF1J has a detection voltage (VS) of 1.25 V (typical), with a guaranteed range of 1.20 V to 1.30 V at 25°C. Its temperature coefficient is 0.01 %/°C, meaning drift remains within ±0.3% over the full –30°C to +85°C operating range. This precision enables repeatable reset assertion across environmental conditions without calibration.
Can the M51945AFP#DF1J be used with a 3.3 V microcontroller reset input?
Yes-the M51945AFP#DF1J's open-collector output allows direct interface to 3.3 V logic. Use a 3.3 V pull-up resistor on the Output pin (Pin 4). When reset is asserted, the output sinks current to GND (Pin 1), pulling the reset line low. Ensure the microcontroller's reset pin tolerates 3.3 V logic levels and accepts active-low assertion, which matches the M51945AFP#DF1J's L-type behavior.
How do I calculate the external resistor values for a 4.2 V reset threshold using the M51945AFP#DF1J?
Use the formula VS ≈ 1.25 × (R1 + R2)/R2. For VS = 4.2 V, rearrange to R1/R2 ≈ (4.2 / 1.25) − 1 = 2.36. Select standard values-for example, R2 = 10 kΩ and R1 = 24 kΩ yields 4.19 V. Confirm with actual measurement, as input current (100 nA typ.) introduces minor error; keep R1 + R2 ≤ 200 kΩ to limit this effect in the M51945AFP#DF1J design.
Is the M51945AFP#DF1J pin-compatible with newer Renesas reset ICs?
No-M51945AFP#DF1J uses a 5-pin SIP package (5P5T) with unique pinout (GND/Input/VCC/Output/NC). Renesas' modern reset ICs (e.g., R3112x series) use SOT-23-3 or SC-70 packages with different pin assignments and integrated pull-ups. Direct replacement requires PCB redesign; the M51945AFP#DF1J remains supported for legacy continuity but is not recommended for new designs per Renesas documentation.
What is the maximum sink current capability of the M51945AFP#DF1J output?
The M51945AFP#DF1J output can safely sink up to 4 mA continuously (recommended) and withstand 6 mA absolute maximum. At 4 mA sink, saturation voltage (Vsat) is ≤ 0.4 V (typ. 0.2 V) when VCC = 5 V. Exceeding 4 mA risks exceeding thermal limits-especially in the 5-pin SIP package-so verify power dissipation (P = Vsat × Isink) stays below 300 mW derated per ambient temperature.
M51945AFP#DF1J Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- -
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
M51945AFP#DF1J FAQ
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6.How does Aetrix verify that M51945AFP#DF1J is sourced from the original manufacturer or authorized distributors?
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7.What is the process for return or replacement of M51945AFP#DF1J?
All M51945AFP#DF1J units undergo pre-shipment inspection (PSI). If there is an issue with M51945AFP#DF1J, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The M51945AFP#DF1J part is unused and in its original packaging.
Return procedure for M51945AFP#DF1J:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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