Renesas M51953AFP#TF1J

Overview

M51953AFP#TF1J from Renesas Electronics is an L-reset-type voltage-detecting system reset IC in 5-pin SIP (5P5T) package, designed to monitor supply voltage and assert active-low reset signals for microcomputers and logic circuits. It features a 4.25 V detection threshold (±0.2 V), 0.6 V minimum operating voltage, 2–17 V supply range, and external capacitor–programmable delay up to ~100 ms with 0.33 µF. Used in CPU reset circuits and battery-check applications where low-voltage operation and simple timing control are critical.

For engineers reviewing the M51953AFP#TF1J datasheet, M51953AFP#TF1J pinout, M51953AFP#TF1J application, or M51953AFP#TF1J equivalent, key selection criteria include its fixed 4.25 V detection level, open-collector output configuration, thermal derating behavior (3 mW/°C), and compatibility with legacy 5-pin SIP layouts requiring no PCB redesign.

Technical Context

The M51953AFP#TF1J implements a precision bandgap-based voltage comparator with 1.25 V internal reference and hysteresis (30–80 mV) to prevent chatter during supply ramp-up/down. Its delay function relies on external capacitor discharge through a constant-current sink (~5 µA typical at Cd pin), enabling predictable tpd ≈ 0.34 × Cd(pF) µs.

As an "L" reset type device, it holds output low until VCC rises above VS (4.25 V), then releases after programmable delay; output remains functional down to VOPL = 0.55 V (typ), supporting brown-out detection in battery-powered systems. The 5-pin SIP package excludes internal pull-up, requiring external RL for logic-level translation.

Key Specifications

Pinout & Package

Package: 5-pin SIP (5P5T), plastic, 2.54 mm pitch, 11.9 mm × 4.0 mm footprint, JEDEC EIAJ code 5P5T. Not recommended for new design per Renesas documentation; superseded by SOP-8 variants but retained for legacy board compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV803EB29DBZR and MAX6326LT29D3+T, the M51953AFP#TF1J offers wider supply range (2–17 V), field-programmable delay via capacitor, and robust low-voltage operation (0.55 V), making it uniquely suited for legacy industrial equipment with variable input rails and timing flexibility requirements.

Availability

M51953AFP#TF1J is available at Aetrix Electronics and suitable for microcomputer reset circuits, battery-check systems, and DC/DC converter supervision requiring stable component supply and long-term obsolescence management.

Supply support for M51953AFP#TF1J 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 timing solutions for industrial, automotive, and infrastructure markets.

The M51953AFP#TF1J belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series, engineered for reliable power-on and brown-out reset in cost-sensitive, space-constrained embedded systems where simplicity and proven field reliability are prioritized over advanced features.

FAQ

What is the detection voltage accuracy of the M51953AFP#TF1J?

The M51953AFP#TF1J has a detection voltage of 4.25 V (typical), with a specified range of 4.05 V to 4.45 V at Ta = 25°C. Its hysteresis is 30–80 mV, ensuring stable transition behavior. Temperature coefficient is 0.01 %/°C, meaning drift is under ±15 mV across –30°C to +85°C operating range. This accuracy supports reliable reset assertion in 5 V systems without calibration.

Can the M51953AFP#TF1J operate from a 3.3 V supply?

Yes, the M51953AFP#TF1J operates from 2 V to 17 V, so 3.3 V is well within its recommended supply range. At 3.3 V, the internal comparator remains functional, and the 4.25 V detection threshold still applies - meaning it will assert reset if VCC falls below that level. However, since 3.3 V < 4.25 V, the device will hold /RESET active continuously unless used with a resistor divider to scale the monitored rail.

What is the maximum allowable delay capacitor value for the M51953AFP#TF1J?

The datasheet specifies a recommended maximum delay capacitor (Cd) of 10 µF. Using larger values increases delay time uncertainty (e.g., 100 µF yields 16–70 s instead of nominal 34 s), degrades response to momentary dips (tPHL increases to ~200 µs), and risks incomplete discharge causing inaccurate timing. For stable, repeatable delays, Cd should be between 4700 pF and 10 µF, with 0.01–0.33 µF offering optimal trade-offs.

Is the M51953AFP#TF1J pin-compatible with newer Renesas reset ICs?

No - the M51953AFP#TF1J uses a 5-pin SIP (5P5T) package with non-standard pinout (GND, NC, Cd, VCC, Output). Newer Renesas reset ICs like the R3112 series use SOT-23-3 or SC70-3 packages with different pin assignments and integrated delay. Direct replacement requires PCB modification; Renesas explicitly marks M51953AFP#TF1J as "not recommend for new design" due to this incompatibility.

Does the M51953AFP#TF1J require an external pull-up resistor on its output?

Yes - the M51953AFP#TF1J has an open-collector output, so an external pull-up resistor (RL) is mandatory. RL must be selected so output sink current stays ≤4 mA (absolute max 6 mA). For a 5 V system, RL ≥ 1.25 kΩ ensures Vsat ≤ 0.4 V. Lower RL improves noise immunity but increases quiescent current; higher RL risks slow rise time or logic-level violation.