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Renesas M51945AL
- Part No.:
- M51945AL
- Manufacturer:
- Renesas
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
M51945AL.pdf
- Description:
- IC SUPERVISOR PWR SUP SUPPORT
- Quantity:
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- Shipping:
Inventory:5,800
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Product details
Overview
M51945AL from Renesas Electronics is an L-type voltage-detecting system reset IC with open-collector output, designed for reliable power-on and brownout reset generation in microcomputer and logic circuits. It features a 1.25 V internal reference, ±15 mV hysteresis, 2–17 V supply range, and supports external resistor-based detection voltage setting from 2 V to 15 V. It is commonly used in CPU reset circuits and battery-check applications.
For engineers reviewing the M51945AL datasheet, M51945AL pinout, M51945AL application, or M51945AL equivalent, key selection considerations include its low-threshold operating voltage (0.6 V typ), 4 µs propagation delay, open-collector output configuration, and compatibility with 5-pin SIP packaging for space-constrained embedded systems.
Technical Context
The M51945AL implements a precision comparator architecture with a stable 1.25 V bandgap reference and 25 µA internal bias current. Its input stage monitors an externally divided supply voltage, triggering a reset when the scaled input falls below the threshold. The open-collector output requires an external pull-up resistor and sinks up to 4 mA at saturation.
It operates as an "L" (active-low) reset device: output goes low when input voltage drops below detection threshold, and remains low until input rises above threshold + hysteresis. Thermal derating is specified at 3 mW/°C above 25°C ambient, with maximum power dissipation of 300 mW in recommended 5-pin SIP package.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Detection Voltage | 1.25 V (typ); sets precise reset threshold via external resistor divider |
| Hysteresis | 15 mV (typ); prevents chatter during slow supply transitions |
| Supply Range | 2 V to 17 V; supports wide-input industrial and automotive auxiliary rails |
| Propagation Delay | tPHL = 4 µs (typ); ensures fast response to supply collapse |
| Output Type | Open-collector; enables wired-OR reset buses and flexible pull-up voltage selection |
| Threshold Operating Voltage | 0.6 V (typ at RL = 22 kΩ); maintains reset assertion even during deep brownout |
| Input Current | 100 nA (typ); minimizes divider network error and power loss |
Pinout & Package
Package: 5-pin SIP (SIP5-P-240-2.54 / 5P5T), lead material Cu alloy, RoHS-compliant, 0.22 g typical mass.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Output | Open-collector active-low reset output; requires external pull-up |
| 2 | Input | Voltage sense input; connects to resistor divider node for adjustable threshold |
| 3 | GND | Analog ground reference; must be low-impedance connection to system ground |
| 4 | Power-supply | VCC supply input; powers internal comparator and bias circuitry |
| 5 | NC | No connection; internally unconnected; must remain floating |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable detection voltage | Settable from 2 V to 15 V using two external resistors; eliminates need for multiple fixed-threshold parts |
| Low operating supply voltage | Operates down to 0.6 V (typ); sustains valid reset assertion during severe undervoltage conditions |
| Wide supply voltage range | 2–17 V operation; compatible with 3.3 V, 5 V, 12 V, and 15 V systems without level-shifting |
| Low input current | 100 nA typical; reduces power loss and accuracy error in high-impedance divider networks |
| Fast propagation delay | 4 µs typical tPHL; ensures timely reset assertion before logic state corruption occurs |
Applications
| Microcontroller Power-On Reset | Battery Voltage Monitoring |
|---|---|
Use Scenario: Ensuring clean initialization of an 8-bit MCU upon 3.3 V rail stabilization after power-up. IC Role / Device Role / Timing Role: Active-low reset generator triggered when VCC crosses 3.0 V threshold set by R1/R2 divider. Use Value: Prevents erratic boot behavior by holding RESET# low until supply reaches stable operating margin. | Use Scenario: Detecting end-of-life voltage drop in a 9 V alkaline battery powering portable instrumentation. IC Role / Device Role / Timing Role: Threshold comparator asserting reset when battery decays below 6.8 V (programmed via external resistors). Use Value: Enables graceful shutdown or low-battery warning before functional failure occurs. |
| DC/DC Converter Supervision | Logic Circuit Brownout Protection |
Use Scenario: Monitoring output of a 5 V isolated DC/DC converter supplying FPGA I/O banks. IC Role / Device Role / Timing Role: L-reset supervisor detecting undershoot events below 4.75 V with 15 mV hysteresis. Use Value: Forces FPGA reconfiguration before I/O corruption or metastability propagates into core logic. | Use Scenario: Protecting TTL/CMOS combinational logic from metastable states during 12 V rail sag in industrial control PLC. IC Role / Device Role / Timing Role: Active-low reset source tied to logic enable inputs, triggered at 10.5 V threshold. Use Value: Halts signal processing pipeline during transient undervoltage, preventing invalid data latching. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-detecting reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV803EB29DBZR | Fixed 2.93 V threshold; SOT-23-3 package; no external resistor adjustment | Suitable only for fixed-voltage reset; lacks programmability and SIP footprint | Select when board space is critical and detection voltage is fixed at 2.93 V |
| MAX809SEUR+T | Fixed 3.08 V threshold; 3-pin SOT-23; built-in pull-up; higher quiescent current (1.1 µA) | Not programmable; incompatible pinout and output structure (push-pull vs open-collector) | Choose for simple plug-in replacement where 3.08 V reset suffices and pull-up is integrated |
Compared with M51945AL, TLV803EB29DBZR offers smaller size but forfeits voltage adjustability and SIP mounting, while MAX809SEUR+T provides integrated pull-up yet lacks hysteresis control and open-collector flexibility required for bus-wired reset architectures.
Availability
M51945AL is available at Aetrix Electronics and suitable for microcontroller reset circuits, battery monitoring systems, and DC/DC converter supervision requiring stable component supply across industrial temperature ranges (–30°C to +85°C).
Supply support for M51945AL 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 Japanese semiconductor manufacturer formed in 2010 through merger of NEC Electronics and Renesas Technology, specializing in microcontrollers, analog, and power management ICs.
The M51945AL belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series, designed specifically for cost-sensitive, high-reliability reset supervision in industrial and consumer logic systems where adjustable thresholds and open-collector outputs are essential.
FAQ
What is the detection voltage accuracy of the M51945AL?
The M51945AL has a nominal detection voltage of 1.25 V with ±0.05 V (1.20 V to 1.30 V) tolerance at 25°C. Its temperature coefficient is 0.01 %/°C, resulting in ±10 mV drift over –30°C to +85°C. This accuracy enables reliable reset assertion across industrial temperature ranges without calibration.
How do I calculate the external resistor values for a desired detection voltage with the M51945AL?
To set detection voltage VS, use VS ≈ 1.25 × (R1 + R2)/R2, where R1 connects between VCC and Input (pin 2), and R2 connects between Input and GND. For example, to achieve 5.0 V detection: 5.0 = 1.25 × (R1 + R2)/R2 → R1/R2 = 3 → choose R2 = 100 kΩ, R1 = 300 kΩ. Account for 100 nA input current error at high resistance values.
Is the M51945AL pin-compatible with other members of the M5194x series?
No - the M51945AL uses a 5-pin SIP package, while M51945AFP/BFP and M51945AL/BL variants use different outlines (PRSP0008DE-C and PRSP0008DA-A SOP packages). Pin count, pin function mapping, and physical layout differ across packages; direct PCB substitution is not supported without layout revision.
What is the maximum sink current capability of the M51945AL output?
The M51945AL open-collector output can safely sink up to 4 mA continuously under normal operating conditions (Ta ≤ 25°C), with absolute maximum rating of 6 mA. Exceeding 4 mA risks exceeding thermal limits and degrading propagation delay or saturation voltage performance, especially at elevated ambient temperatures.
Does the M51945AL require a bypass capacitor on its supply pin?
Yes - Renesas recommends placing both a bulk capacitor (C1, e.g., 10 µF electrolytic) and a high-frequency ceramic capacitor (C2, e.g., 0.1 µF) between VCC (pin 4) and GND (pin 3) to suppress ripple and noise. This ensures stable internal biasing and prevents false resets caused by supply transients, particularly in noisy industrial environments.
M51945AL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
M51945AL FAQ
1.How can I place an order for M51945AL through Aetrix?
Please submit a Request for Quotation (RFQ) for M51945AL on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for M51945AL reliable?
The price and inventory of M51945AL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M51945AL is usually 5 days.
3.What payment methods are accepted for M51945AL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M51945AL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M51945AL?
M51945AL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M51945AL order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for M51945AL?
For technical support, including M51945AL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M51945AL requirements.
6.How does Aetrix verify that M51945AL is sourced from the original manufacturer or authorized distributors?
All M51945AL products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that M51945AL meets industry standards.
7.What is the process for return or replacement of M51945AL?
All M51945AL units undergo pre-shipment inspection (PSI). If there is an issue with M51945AL, 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 M51945AL part is unused and in its original packaging.
Return procedure for M51945AL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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