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Renesas M51945BFP#CF1J
- Part No.:
- M51945BFP#CF1J
- Manufacturer:
- Renesas
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
M51945BFP#CF1J.pdf
- Description:
- VOLTAGE DETECTING, SYSTEM RESETT
- Quantity:
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Inventory:17,655
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Product details
Overview
M51945BFP#CF1J from Renesas Electronics is an L-reset-type voltage-detecting system reset IC with open-collector output, designed for reliable power-on and brownout reset generation in microcomputer and logic systems. It features a 1.25 V internal reference, 15 mV typical hysteresis, 2–17 V supply range, and operates down to 0.55 V supply (RL = 100 kΩ), enabling use in battery-backed and low-voltage embedded applications.
For engineers reviewing the M51945BFP#CF1J datasheet, M51945BFP#CF1J pinout, M51945BFP#CF1J application, or M51945BFP#CF1J equivalent, key selection criteria include detection threshold configurability via external resistors, open-collector output compatibility with mixed-voltage logic interfaces, temperature-stable reset assertion, and SIP-5 package suitability for space-constrained industrial control PCBs.
Technical Context
The M51945BFP#CF1J implements a precision comparator architecture with a trimmed 1.25 V bandgap reference and 25 µA internal bias current, enabling accurate input voltage monitoring across its full 2–17 V supply range. Its L-reset behavior asserts a low-level active reset signal when the monitored input voltage falls below the set detection threshold.
As an open-collector (Type B) device, it requires an external pull-up resistor to define the high-state output voltage and sink capability-supporting flexible interface levels up to 17 V while maintaining compatibility with 3.3 V, 5 V, or 12 V logic families. Propagation delay is under 4 µs for VCC transitions, ensuring fast response to supply faults.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Detection Voltage | 1.25 V (typical); sets precise reset threshold via external R1/R2 divider on Input pin |
| Hysteresis | 15 mV (typical); prevents chatter during slow or noisy supply ramp-down |
| Supply Range | 2 V to 17 V; supports wide-input DC/DC converters and multi-rail systems |
| Output Type | Open-collector (Type B); enables level-shifting and wired-OR reset bus configurations |
| Reset Polarity | L-reset (active-low); directly drives standard microcontroller /RESET pins requiring low assertion |
| Threshold Operating Voltage | 0.55 V (typical at RL = 100 kΩ); ensures functional reset assertion even during deep brownout |
| Propagation Delay | 4 µs max (tPHL); guarantees sub-microsecond response to supply collapse |
Pinout & Package
Package: 5-pin SIP (SIP5-P-240-2.54, EIAJ code 5P5T), 11.9 mm × 2.54 mm footprint, through-hole mount, plastic body with Cu alloy leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Ground reference for internal comparator and output stage; must be low-impedance connection |
| 2 | Input | Voltage sensing node; accepts divided supply for configurable detection threshold (1.25 × (R1+R2)/R2) |
| 3 | Power-supply | VCC input; powers internal circuitry and defines upper limit for open-collector pull-up voltage |
| 4 | Output | Open-collector drain; sinks current when reset is asserted (low), requires external pull-up resistor |
| 5 | NC | No connection; internally unconnected; must remain floating or grounded per layout best practice |
Key Features
| Feature | Design Value |
|---|---|
| Configurable detection voltage | Settable from 2 V to 15 V using two external resistors-eliminates need for multiple fixed-threshold ICs |
| Low operating supply voltage | Functional down to 0.55 V supply (RL = 100 kΩ), enabling reliable reset during battery depletion or cold-start conditions |
| Wide supply voltage range | 2–17 V operation accommodates 3.3 V, 5 V, 12 V, and 15 V systems without level-shifting components |
| Temperature-stable reference | 0.01 %/°C detecting voltage drift ensures consistent reset timing across –30°C to +85°C industrial range |
| Fast propagation delay | <4 µs tPHL ensures immediate reset assertion on supply collapse-critical for data retention and state recovery |
Applications
| Microcontroller Power-On Reset | Battery Backup Monitoring |
|---|---|
|
Use Scenario: Ensuring deterministic startup of an 8-bit MCU after power application or recovery from brownout. IC Role / Device Role / Timing Role: Generates clean, debounced active-low reset pulse synchronized to VCC stabilization. Use Value: Prevents illegal opcode execution and register corruption by holding /RESET until VCC exceeds 1.25×(R1+R2)/R2 with 15 mV hysteresis. |
Use Scenario: Monitoring backup coin-cell voltage in a real-time clock (RTC) module to initiate graceful shutdown before data loss. IC Role / Device Role / Timing Role: Detects falling VBAT below 2.5 V and asserts reset to halt RTC writes and preserve SRAM contents. Use Value: Configurable threshold (via R1/R2) allows precise match to battery end-of-life voltage, extending usable runtime. |
| Industrial PLC I/O Module | DC/DC Converter Supervision |
|
Use Scenario: Providing fault-tolerant reset signaling in a DIN-rail mounted programmable logic controller with 24 V nominal supply. IC Role / Device Role / Timing Role: Monitors 5 V logic rail derived from 24 V input; asserts reset if rail drops below 4.75 V due to overload or regulator failure. Use Value: Open-collector output interfaces directly to 24 V-rated optocoupler inputs, enabling isolation without additional level shifters. |
Use Scenario: Validating stable output from a 12 V buck converter before enabling downstream FPGAs or ADCs. IC Role / Device Role / Timing Role: Senses converter output via resistive divider; holds system in reset until output reaches and sustains ≥11.4 V for >10 ms. Use Value: 2–17 V supply range allows direct powering from converter output, eliminating auxiliary bias supply. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-detecting reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV803DBZT | Fixed 3.08 V threshold; SOT-23-3 package; no external resistor configuration | Suitable only for fixed 3.3 V systems; lacks adjustable threshold and wider supply range | Select when board space is critical and detection voltage is fixed at 3.08 V; not suitable for 5 V or 12 V rails. |
| MAX809SEUR+T | Fixed 3.08 V threshold; SOT-23-3; push-pull output; 1.2 µA quiescent current | Lower IQ but no configurability; incompatible with open-collector bus architectures | Prefer for ultra-low-power battery applications where fixed 3.08 V reset suffices and pull-up resistors are undesirable. |
Compared with TLV803DBZT and MAX809SEUR+T, the M51945BFP#CF1J provides unique configurability across 2–15 V thresholds and robust 2–17 V operation-making it the only choice among the three for multi-rail, legacy, or custom-voltage systems requiring field-adjustable reset points.
Availability
M51945BFP#CF1J is available at Aetrix Electronics and suitable for industrial control panels, battery-powered instrumentation, PLC I/O modules, and DC/DC converter supervision requiring stable component supply and long-term design continuity.
Supply support for M51945BFP#CF1J 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 delivering microcontrollers, analog, power, and SoC solutions for automotive, industrial, and IoT applications.
The M51945BFP#CF1J belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series-designed specifically for cost-sensitive, high-reliability embedded systems requiring configurable, low-voltage reset functionality without external comparators or references.
FAQ
What is the detection voltage accuracy of the M51945BFP#CF1J?
The M51945BFP#CF1J has a detection voltage of 1.25 V (typical), with a min/max range of 1.20 V to 1.30 V at 25°C. Its hysteresis is 15 mV (typical), and temperature coefficient is 0.01 %/°C-ensuring stable reset thresholds across –30°C to +85°C. These values are measured under standard test conditions and apply directly to the M51945BFP#CF1J.
How do I configure the reset threshold for a 5 V supply using the M51945BFP#CF1J?
To set a 5 V detection threshold, use the formula VS ≈ 1.25 × (R1 + R2)/R2. For VS = 5.0 V, select R2 = 10 kΩ and R1 = 30 kΩ (yielding 5.0 V). Ensure R1 + R2 ≤ 100 kΩ to minimize error from input current (100 nA typ). The M51945BFP#CF1J's Input pin connects to the R1–R2 junction, and GND connects to the bottom of R2.
Does the M51945BFP#CF1J support open-collector interfacing with 12 V logic?
Yes-the M51945BFP#CF1J is a Type B (open-collector) device. Its Output pin can safely sink up to 4 mA when pulled up to 12 V (within its 2–17 V supply range), making it compatible with 12 V TTL or discrete transistor interfaces. Always limit sink current to ≤4 mA using appropriate pull-up resistance (e.g., 3 kΩ for 12 V).
Is the M51945BFP#CF1J suitable for new designs given the "Not recommend for new design" notice?
The "Not recommend for new design" notice applies to the entire M51945A,B/M51946A,B family per Renesas' 2007 documentation. However, M51945BFP#CF1J remains actively stocked and supported by Aetrix Electronics for legacy system repair, long-lifecycle industrial maintenance, and cost-sensitive applications where its SIP-5 footprint and resistor-configurable reset provide unmatched value.
What is the minimum supply voltage required for the M51945BFP#CF1J to assert reset correctly?
The M51945BFP#CF1J maintains valid reset assertion down to a supply voltage of 0.55 V (typical) when loaded with RL = 100 kΩ-enabling reliable brownout detection even during severe undervoltage events. This threshold is specified as VOPL (threshold operating voltage) and is confirmed in the Electrical Characteristics table for the M51945BFP#CF1J.
M51945BFP#CF1J 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:
- -
M51945BFP#CF1J FAQ
1.How can I place an order for M51945BFP#CF1J through Aetrix?
Please submit a Request for Quotation (RFQ) for M51945BFP#CF1J 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#CF1J reliable?
The price and inventory of M51945BFP#CF1J are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M51945BFP#CF1J is usually 5 days.
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Once your M51945BFP#CF1J 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 M51945BFP#CF1J?
For technical support, including M51945BFP#CF1J datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M51945BFP#CF1J requirements.
6.How does Aetrix verify that M51945BFP#CF1J is sourced from the original manufacturer or authorized distributors?
All M51945BFP#CF1J 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#CF1J meets industry standards.
7.What is the process for return or replacement of M51945BFP#CF1J?
All M51945BFP#CF1J units undergo pre-shipment inspection (PSI). If there is an issue with M51945BFP#CF1J, 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#CF1J part is unused and in its original packaging.
Return procedure for M51945BFP#CF1J:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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