Renesas M51945BFP#CF0R

Overview

M51945BFP#CF0R from Renesas Electronics is an L-type (active-low) voltage-detecting system reset IC with open-collector output, designed for reliable power-on and brown-out reset generation in microcontroller and logic systems. It features a 1.25 V internal reference, ±15 mV hysteresis, 2–17 V supply range, and external resistor-programmable detection threshold - enabling precise reset voltage setting from 2 V to 15 V in battery monitoring, DC/DC converter supervision, and embedded MCU reset circuits.

For engineers reviewing the M51945BFP#CF0R datasheet, M51945BFP#CF0R pinout, M51945BFP#CF0R application, or M51945BFP#CF0R equivalent, key selection considerations include its open-collector output configuration, low 280 µA typical quiescent current at 5 V, –30°C to +85°C operating temperature range, and compatibility with standard 5-pin SIP packaging for space-constrained industrial control and legacy embedded designs.

Technical Context

The M51945BFP#CF0R implements a precision comparator-based detection architecture with a stable 1.25 V bandgap reference and 25 µA internal bias current. Its input stage monitors an externally divided supply rail, while the open-collector output drives external pull-up networks to generate active-low reset signals synchronized to supply transitions.

It supports both shared- and independent-power-supply configurations, with strict input voltage constraints (0.8 V < VIN < VCC–0.3 V for VCC ≤ 7 V) and thermal derating of 3 mW/°C above 25°C ambient. The device is explicitly designated as "not recommend for new design" per Renesas documentation, indicating obsolescence status and suitability only for continuity support of existing hardware.

Key Specifications

Pinout & Package

Package: 5-pin SIP (Single In-line Package), outline code 5P5T, dimensions 11.9 × 2.54 mm, plastic body with Cu alloy leads and Ni/Pd/Au plating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage-detecting reset applications.

Compared with M51945BFP#CF0R, TLV803DBZQ1 offers automotive qualification but lacks programmability and uses push-pull output, while MAX809SEUR+T reduces power consumption by >99% but sacrifices adjustable detection voltage - both require schematic and layout updates due to differing pin functions and output architectures.

Availability

M51945BFP#CF0R is available at Aetrix Electronics and suitable for industrial control systems, legacy embedded MCU platforms, and battery-powered instrumentation requiring stable component supply and long-term continuity support.

Supply support for M51945BFP#CF0R 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 specializing in microcontrollers, analog and power devices, and system-on-chip solutions for industrial, automotive, and infrastructure markets.

The M51945BFP#CF0R belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series, designed specifically for robust, low-cost reset generation in resource-constrained embedded systems where external resistor programming and wide supply tolerance are critical.

FAQ

What is the detection voltage accuracy of the M51945BFP#CF0R?

The M51945BFP#CF0R has a nominal detection voltage of 1.25 V with ±0.05 V (1.20–1.30 V) tolerance over temperature and process variation. Its 0.01 %/°C temperature coefficient ensures drift remains within ±0.85 mV over the –30°C to +85°C operating range, making it suitable for precision reset applications where supply margin is tight. This specification applies directly to the internal reference used in the M51945BFP#CF0R comparator circuit.

Can the M51945BFP#CF0R be used with a 3.3 V supply?

Yes, the M51945BFP#CF0R operates reliably across 2 V to 17 V, including 3.3 V systems. At 3.3 V, its typical quiescent current is ~280 µA, and the output saturation voltage remains ≤0.4 V when sinking 4 mA - ensuring strong logic-low assertion for 3.3 V CMOS inputs. The input voltage must stay within 0.8 V to 3.0 V (VCC–0.3 V), which is satisfied when using standard resistor dividers. This behavior is confirmed in the M51945BFP#CF0R electrical characteristics table.

Why does the M51945BFP#CF0R have a "Not recommend for new design" notice?

The "Not recommend for new design" designation reflects Renesas' product lifecycle policy: the M51945BFP#CF0R remains fully functional and supported for existing designs but has been superseded by more integrated, lower-power, or AEC-Q100-qualified alternatives. No immediate discontinuation is planned, but long-term availability beyond 2027 is not guaranteed. Customers designing new products should evaluate modern equivalents like the TLV803 series. This notice appears in the official M51945BFP#CF0R datasheet revision 3.00.

How do I calculate the external resistor values for a 4.2 V reset threshold with the M51945BFP#CF0R?

Use the formula VS = 1.25 × (R1 + R2)/R2, solving for R1/R2 = (VS/1.25) – 1. For VS = 4.2 V, R1/R2 ≈ 2.36. Select R2 = 100 kΩ → R1 = 236 kΩ (use standard 240 kΩ). Input current error (<500 nA) introduces <2.4 mV error at this impedance, well within ±50 mV hysteresis. This calculation method is documented in the M51945BFP#CF0R application notes on page 7 of REJ03D0774-0300.

Is the M51945BFP#CF0R RoHS compliant?

Yes, the M51945BFP#CF0R meets EU RoHS Directive requirements. Renesas confirms compliance in its environmental data sheets and product change notifications, with lead-free terminations (Ni/Pd/Au plating) and halogen-free molding compound. This applies to all units shipped after September 2007, consistent with the M51945BFP#CF0R revision 3.00 release date and Renesas' corporate RoHS implementation timeline.