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Renesas M51945BFP#DF0R
- Part No.:
- M51945BFP#DF0R
- Manufacturer:
- Renesas
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
M51945BFP#DF0R.pdf
- Description:
- IC SUPERVISOR VOLT DET SYS RESET
- Quantity:
- Payment:
- Shipping:
Inventory:10,000
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Product details
Overview
M51945BFP#DF0R from Renesas Electronics is a voltage-detecting system reset IC with open-collector output (Type B), designed for low-voltage logic circuit reset applications. It features 1.25 V internal reference, ±15 mV hysteresis, 2–17 V supply range, and operates down to 0.55 V supply voltage. Used in microcomputer and CPU reset circuits where external resistor programming of detection threshold is required.
For engineers reviewing the M51945BFP#DF0R datasheet, M51945BFP#DF0R pinout, M51945BFP#DF0R application, or M51945BFP#DF0R equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and two confirmed alternative parts with documented functional and application-level differences.
Technical Context
The M51945BFP#DF0R implements a precision comparator architecture with a stable 1.25 V bandgap reference and 25 µA typical input bias current. Its input stage monitors an externally divided supply voltage, triggering reset when the input falls below the threshold.
As a Type B device, it delivers an open-collector output requiring an external pull-up resistor, enabling flexible voltage-level translation and wired-OR configurations. The reset assertion is active-low ("L" reset type), with propagation delay under 4 µs during VCC drop and under 2 µs during recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Detection Voltage | 1.25 V (typical); sets precise reset threshold via external R1/R2 divider - enables custom detection from 2 V to 15 V |
| Hysteresis | 15 mV (typical); prevents chatter near threshold during slow-rising/falling supply transitions |
| Supply Range | 2 V to 17 V; supports wide-input DC/DC converters and battery-backed systems without auxiliary regulation |
| Threshold Operating Voltage | 0.55 V (typical at RL = 2.2 kΩ); ensures reliable reset assertion even during deep brown-out conditions |
| Output Type | Open-collector (Type B); allows level-shifting, multi-source reset arbitration, and compatibility with varied logic families |
| Propagation Delay | tPHL ≤ 4 µs, tPLH ≤ 2 µs; guarantees fast, deterministic reset timing critical for CPU boot integrity |
| Input Current | 100 nA (typical at VIN = 1.25 V); minimizes divider network error and power loss in high-impedance sensing |
Pinout & Package
Package: 5-pin SIP (5P5T), plastic single-in-line package, 2.54 mm pitch, 11.9 × 4.0 mm footprint, lead-free (Pb-free) Cu alloy leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Ground reference for internal circuitry and output sink path; must be low-impedance connection |
| 2 | Input | Voltage-sense node; accepts externally divided supply; input range limited to 0.8 V–(VCC−0.3 V) |
| 3 | Power-supply | VCC pin; powers internal comparator and reference; supports 2–17 V operation with 18 V absolute max |
| 4 | Output | Open-collector NPN output; sinks up to 4 mA; requires external pull-up for logic-high state |
| 5 | NC | No internal connection; must remain unconnected per datasheet; not usable as thermal pad or ground |
Key Features
| Feature | Design Value |
|---|---|
| Externally programmable detection voltage | Set via two-resistor divider on Input pin; eliminates need for multiple fixed-threshold variants |
| Ultra-low operating supply voltage | 0.55 V minimum VCC ensures reset remains asserted through severe brown-out before system collapse |
| Low input bias current | 100 nA typical minimizes voltage error across high-value divider resistors, preserving accuracy |
| Wide supply voltage range | 2–17 V operation supports direct interface with unregulated battery rails, industrial supplies, and DC/DC outputs |
| Fast, guaranteed reset timing | Sub-5 µs propagation delays ensure CPU reset meets tight boot timing requirements across temperature |
Applications
| Microcontroller Power-On Reset | Battery Voltage Monitoring |
|---|---|
|
Use Scenario: Ensures clean, synchronized reset of an 8-bit MCU during cold start or battery insertion. IC Role / Device Role / Timing Role: Active-low reset generator triggered when VCC rises above programmed threshold (e.g., 2.7 V). Use Value: Prevents erratic MCU execution by holding reset until stable supply is confirmed - no external RC timing components needed. |
Use Scenario: Monitors lithium coin-cell voltage in portable medical sensors to warn of end-of-life. IC Role / Device Role / Timing Role: Threshold detector asserting reset signal when cell voltage drops below 2.4 V. Use Value: Enables early low-battery flag generation using same reset output line - avoids dedicated ADC or comparator. |
| DC/DC Converter Supervision | Industrial Logic System Reset |
|
Use Scenario: Validates output stability of a 5 V isolated DC/DC converter powering PLC I/O modules. IC Role / Device Role / Timing Role: "L" reset monitor on converter output rail; asserts reset if output sags >5% for >10 µs. Use Value: Provides sub-microsecond response to transient faults - faster than microcontroller-based monitoring alone. |
Use Scenario: Coordinates power-up sequencing across multiple FPGA and ASIC subsystems in factory automation hardware. IC Role / Device Role / Timing Role: Centralized reset arbiter using open-collector wired-OR to combine multiple reset sources. Use Value: Enables deterministic, glitch-free initialization across heterogeneous logic blocks without timing skew. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-detecting reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV803EB27DBZR | Fixed 2.7 V threshold; SOT-23-3 package; 3.5 µA quiescent current; no external programming | Not suitable where adjustable detection or SIP mounting is required; better for space-constrained, fixed-threshold designs | Select when board area is critical and detection voltage is fixed at 2.7 V - eliminates R1/R2 network and saves PCB space |
| MAX6326LT29D3+T | 2.93 V fixed threshold; SC70-3; 0.9 µA IQ; built-in watchdog timer; push-pull output | Provides watchdog capability absent in M51945BFP#DF0R; incompatible pinout and output drive architecture | Choose when system-level reliability requires both power-on reset and periodic watchdog timeout - adds supervision layer beyond basic voltage detection |
Compared with TLV803EB27DBZR and MAX6326LT29D3+T, the M51945BFP#DF0R uniquely supports user-defined reset thresholds via external resistors in a through-hole SIP package, making it suitable for legacy industrial designs requiring field-adjustable brown-out levels and mechanical robustness.
Availability
M51945BFP#DF0R is available at Aetrix Electronics and suitable for microcontroller reset, battery monitoring, DC/DC supervision, and industrial logic system reset applications requiring stable component supply and long-lifecycle support.
Supply support for M51945BFP#DF0R 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 automotive, industrial, and enterprise applications.
The M51945BFP#DF0R belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series - designed specifically for cost-sensitive, high-reliability reset functions in industrial control, instrumentation, and embedded systems where programmable threshold and wide supply range are essential.
FAQ
What is the function of the NC pin on the M51945BFP#DF0R?
The NC (No Connection) pin on the M51945BFP#DF0R is internally unconnected and must remain floating - it serves no electrical function and is not intended for grounding, thermal relief, or mechanical anchoring. Connecting it may cause unpredictable behavior or violate absolute maximum ratings per the Renesas datasheet REJ03D0774-0300.
Can the M51945BFP#DF0R be used with a 3.3 V logic system?
Yes, the M51945BFP#DF0R supports 3.3 V operation within its 2–17 V supply range. Its open-collector output requires an external pull-up to 3.3 V, and its input voltage range (0.8 V to VCC−0.3 V) accommodates standard 3.3 V logic thresholds. Detection voltage is set independently via external resistors.
How does the M51945BFP#DF0R differ from the M51945AFP variant?
The M51945BFP#DF0R is Type B (open-collector output), while the M51945AFP is Type A (built-in load). This means M51945BFP#DF0R requires an external pull-up resistor and supports wired-OR configurations, whereas M51945AFP drives high internally and cannot be shared across multiple reset sources.
Is the M51945BFP#DF0R RoHS compliant?
Yes, the M51945BFP#DF0R is RoHS compliant per Renesas documentation and uses lead-free (Pb-free) Cu alloy leads. It meets EU Directive 2011/65/EU requirements, and its package marking confirms compliance - verified in the official Renesas reliability handbook and product change notices.
Why does the datasheet state "Not recommend for new design" for the M51945BFP#DF0R?
The "Not recommend for new design" notice reflects Renesas' product lifecycle policy: the M51945BFP#DF0R remains fully functional and supported but has been superseded by newer, lower-power, or enhanced-feature reset ICs. It is still available for legacy repair, continuity, and long-lifecycle industrial programs where qualification stability is prioritized over feature updates.
M51945BFP#DF0R 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:
- -
M51945BFP#DF0R FAQ
1.How can I place an order for M51945BFP#DF0R through Aetrix?
Please submit a Request for Quotation (RFQ) for M51945BFP#DF0R 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 M51945BFP#DF0R reliable?
The price and inventory of M51945BFP#DF0R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M51945BFP#DF0R is usually 5 days.
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5.How can I obtain technical support or documentation for M51945BFP#DF0R?
For technical support, including M51945BFP#DF0R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M51945BFP#DF0R requirements.
6.How does Aetrix verify that M51945BFP#DF0R is sourced from the original manufacturer or authorized distributors?
All M51945BFP#DF0R 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 M51945BFP#DF0R meets industry standards.
7.What is the process for return or replacement of M51945BFP#DF0R?
All M51945BFP#DF0R units undergo pre-shipment inspection (PSI). If there is an issue with M51945BFP#DF0R, 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 M51945BFP#DF0R part is unused and in its original packaging.
Return procedure for M51945BFP#DF0R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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