Renesas RNA51958BP#T0

Overview

RNA51958BP#T0 from Renesas Electronics is a voltage-detecting system reset IC with open-collector output (Type B), designed for reliable power-on and brown-out reset generation in microcontrollers and logic circuits. It features a 1.25 V typical detection threshold, 2–17 V supply range, and externally adjustable delay time via capacitor (e.g., ~3.4 ms at 0.01 µF). It is used in battery-check, level-detection, and waveform-shaping circuits where precise, configurable reset timing is required.

For engineers reviewing the RNA51958BP#T0 datasheet, RNA51958BP#T0 pinout, RNA51958BP#T0 application, or RNA51958BP#T0 equivalent, key selection considerations include its open-collector output configuration, external resistor-settable detection voltage (VS × (R1+R2)/R2), ambient temperature stability (±0.01 %/°C), and compatibility with DIP-8 PCB footprints for through-hole industrial control designs.

Technical Context

The RNA51958BP#T0 implements a precision bandgap-based voltage comparator with 15 mV typical hysteresis to prevent chatter during threshold crossing. Its internal constant-current source (−5 µA typ at Cd pin) enables predictable RC delay timing independent of supply voltage variation.

As a Type B variant, it uses an open-collector NPN output stage requiring an external pull-up resistor (RL), allowing flexible high-level voltage selection up to 17 V and enabling wired-OR reset bus configurations. Input voltage is referenced to GND and supports operation across the full 2–17 V supply range without internal regulation.

Key Specifications

Pinout & Package

RNA51958BP#T0 is housed in an 8-pin DIP package (PRDP0008AF-B), 9.6 mm × 6.3 mm body, 2.54 mm pitch, Ni/Pd/Au-plated leads. Through-hole mounting supports high-reliability industrial assembly and thermal cycling robustness.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV803EB29DBZR and MAX809SEUR+T, RNA51958BP#T0 uniquely supports both resistor-programmable detection voltage and capacitor-scaled delay timing in a through-hole DIP-8 package - making it optimal for legacy industrial designs requiring field-configurable reset behavior without firmware involvement.

Availability

RNA51958BP#T0 is available at Aetrix Electronics and suitable for industrial control panels, battery-powered instrumentation, and DC/DC converter supervision requiring stable component supply, long-lifecycle support, and through-hole assembly compatibility.

Supply support for RNA51958BP#T0 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 specializing in microcontrollers, analog, and power management ICs, with deep expertise in industrial, automotive, and infrastructure applications.

RNA51958BP#T0 belongs to Renesas' Voltage Detecting, System Resetting IC Series - engineered for robust, parameter-adjustable reset generation in cost-sensitive, high-reliability embedded systems without software dependency.

FAQ

What is the function of Pin 6 (Delay capacitor) on the RNA51958BP#T0?

Pin 6 connects to an external timing capacitor (Cd) that controls the reset delay duration. The RNA51958BP#T0 sources a constant −5 µA current into this capacitor, resulting in a linear voltage ramp; reset release occurs when the ramp crosses an internal threshold. Delay time follows td ≈ 0.34 × Cd(pF) µs - for example, 0.01 µF yields ~3.4 ms. Capacitor values between 4.7 nF and 10 µF are supported.

Can RNA51958BP#T0 be used with a 3.3 V microcontroller supply?

Yes, RNA51958BP#T0 operates from 2 V to 17 V, so it fully supports 3.3 V systems. When used with a 3.3 V supply, set the detection voltage using R1/R2 to trigger reset below the MCU's minimum operating voltage (e.g., 2.7 V). Its open-collector output requires a pull-up to 3.3 V, and the output sink capability (6 mA max) ensures reliable drive into standard CMOS inputs.

How does the hysteresis of RNA51958BP#T0 improve system reliability?

The RNA51958BP#T0 provides 15 mV typical hysteresis (ΔVS) between detect and release thresholds. This prevents oscillatory reset toggling when supply voltage lingers near the trip point due to ripple, load transients, or slow ramp rates. For a 1.25 V nominal threshold, release occurs at ~1.235 V - ensuring clean, single-pulse reset assertion even under marginal power conditions.

What is the maximum allowable value for the external timing capacitor Cd on RNA51958BP#T0?

The recommended maximum for Cd is 10 µF. Larger values cause increasing timing uncertainty (e.g., ±100% variation at 100 µF), reduced sensitivity to momentary dips (<100 µs reaction time), and incomplete discharge leading to inaccurate delays. For stable, repeatable performance, Renesas specifies Cd ≤ 10 µF - with optimal accuracy achieved between 0.01 µF and 3.3 µF per datasheet characterization.

Is RNA51958BP#T0 pin-compatible with other parts in the RNA51958 series?

RNA51958BP#T0 shares identical pinout and footprint with RNA51958APT0 (DIP-8 Type A), RNA51958AFPH0 (SOP-8 Type A), and RNA51958BFPH0 (SOP-8 Type B). However, Type A (built-in load) and Type B (open-collector) differ electrically at Pin 4 (Output): Type A drives high actively, while Type B requires external pull-up. Swapping types requires schematic and layout review for output interface compatibility.