Renesas M51943AHP#CF0J

Overview

M51943AHP#CF0J from Renesas is a voltage-detecting system reset IC with 4.25 V detection threshold, open-collector output (Type B), and −30°C to +85°C operating temperature range. It monitors supply voltage and asserts an active-low reset signal to microcomputers and logic circuits during brownout conditions, supporting battery-check and level-detect applications in embedded power management.

For engineers reviewing the M51943AHP#CF0J datasheet, M51943AHP#CF0J pinout, M51943AHP#CF0J application, or M51943AHP#CF0J equivalent, key selection criteria include its 4.25 V ±0.2 V detection voltage, 50 mV typical hysteresis, 0.55 V typical threshold operating voltage, open-collector output configuration, and compatibility with 3-pin SIP (5P5T) packaging for space-constrained PCB layouts.

Technical Context

The M51943AHP#CF0J implements a precision bandgap-based voltage detector with internal 1.25 V reference and resistor divider network (R1/R2) to set the 4.25 V trip point. Its "L" reset type asserts low on undervoltage and remains low until VCC rises above VS + ΔVS.

As a Type B variant, it features an open-collector output requiring external pull-up, enabling flexible logic-level interfacing and wired-OR reset bus configurations. The device draws only 340 µA typical supply current at 5 V and operates down to 0.55 V supply - critical for battery-backed systems recovering from deep discharge.

Key Specifications

Pinout & Package

Package: 5-pin SIP (5P5T), plastic through-hole, 2.54 mm pitch, 11.9 mm × 4.0 mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with APX803S-42SA-7 and TPS3808G33DBVR, the M51943AHP#CF0J provides exact 4.25 V detection with industry-standard hysteresis and through-hole 5P5T packaging - making it optimal for legacy industrial designs requiring proven reliability, mechanical robustness, and compatibility with wave-soldered assemblies.

Availability

M51943AHP#CF0J is available at Aetrix Electronics and suitable for battery-check circuits, microcontroller reset supervision, and DC/DC converter monitoring requiring stable component supply across extended product lifecycles.

Supply support for M51943AHP#CF0J 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 is a global semiconductor leader delivering microcontrollers, analog, power, and SoC solutions for automotive, industrial, and enterprise applications.

The M51943AHP#CF0J belongs to Renesas' legacy voltage-monitoring IC family designed specifically for cost-sensitive, high-reliability industrial reset and brownout protection - emphasizing precision threshold accuracy, wide supply tolerance, and long-term parametric stability.

FAQ

What is the detection voltage accuracy of the M51943AHP#CF0J?

The M51943AHP#CF0J has a detection voltage of 4.25 V (typical), with a guaranteed range of 4.05 V to 4.45 V at 25°C. This ±0.2 V tolerance ensures reliable brownout detection for 5 V systems while accommodating manufacturing variance and temperature drift. The device also exhibits only 0.01 %/°C temperature coefficient, maintaining accuracy across its full −30°C to +85°C operating range - critical for outdoor or unregulated industrial environments where the M51943AHP#CF0J is commonly deployed.

Does the M51943AHP#CF0J require an external pull-up resistor?

Yes, the M51943AHP#CF0J is a Type B device with an open-collector output, so it requires an external pull-up resistor to define the logic-high state. Typical values range from 4.7 kΩ to 10 kΩ, depending on bus capacitance and rise-time requirements. Without this resistor, the output remains floating and cannot drive high - a key distinction from Type A variants like M51943AML which integrate a constant-current load. This design choice gives system designers flexibility in setting output voltage levels and enables wired-OR reset bus topologies using the M51943AHP#CF0J.

Can the M51943AHP#CF0J operate from a 3.3 V supply?

Yes, the M51943AHP#CF0J supports supply voltages from 2 V to 17 V, fully covering 3.3 V operation. At 3.3 V, the device remains functional and maintains its 4.25 V detection threshold - meaning it will assert reset when VCC falls below that level, even if the supply itself is nominally 3.3 V. However, note that the output saturation voltage (V_sat) is specified at ≤0.4 V with 4 mA sink current, ensuring clean low-state signaling into 3.3 V logic families. This makes the M51943AHP#CF0J suitable for mixed-voltage systems where reset coordination across rails is required.

What is the minimum supply voltage needed for the M51943AHP#CF0J to function?

The M51943AHP#CF0J can operate down to a minimum supply voltage of 0.55 V (typical), known as the threshold operating voltage (V_OPL). This allows the device to assert reset even during severe battery sag or capacitor discharge events - a key advantage in battery-backed systems. While the detection threshold remains fixed at 4.25 V, the internal circuitry continues to monitor and respond as long as VCC stays above ~0.55 V. This behavior is confirmed in the datasheet's "Threshold operating voltage" specification and distinguishes the M51943AHP#CF0J from many competing supervisors that cease operation near their detection threshold.

Which package does the M51943AHP#CF0J use, and is it RoHS-compliant?

The M51943AHP#CF0J uses the 5-pin SIP (5P5T) package - a through-hole, plastic 5-pin inline package with 2.54 mm lead pitch and JEDEC code EIAJ 5P5T. Per Renesas documentation and package markings, this variant is lead-free and RoHS-compliant. The package dimensions are 11.9 mm × 4.0 mm × 9.5 mm (L×W×H), with a typical mass of 0.34 g. Its robust through-hole construction provides mechanical reliability in high-vibration environments - a design consideration reflected in the M51943AHP#CF0J's qualification for industrial applications.