Renesas RNA51958AP#T0

Overview

RNA51958AP#T0 from Renesas Electronics is a voltage-detecting system reset IC with adjustable detection threshold via external resistor divider, 1.25 V internal reference, open-collector output (Type B), and capacitor-programmable delay time up to ~7 ms at 0.01 µF - used for reliable power-on reset in microcomputer and logic circuits.

For engineers reviewing the RNA51958AP#T0 datasheet, RNA51958AP#T0 pinout, RNA51958AP#T0 application, or RNA51958AP#T0 equivalent, key selection considerations include its 2–17 V supply range, ±15 mV hysteresis, 360 µA typical circuit current at 5 V, –40°C to +85°C operating temperature, and DIP-8 package compatibility with legacy through-hole designs.

Technical Context

The RNA51958AP#T0 implements a precision comparator with 1.25 V bandgap reference and hysteresis to avoid chatter during voltage transitions. Its Type B configuration features an open-collector output requiring external pull-up, enabling flexible logic-level interfacing across different supply domains.

Delay timing is generated by charging an external capacitor (Cd) through a constant-current source (~5 µA typ), yielding tpd ≈ 0.34 × Cd(pF) µs. Input voltage sensing occurs at the IN pin (Pin 2), referenced to GND, with input current limited to 100 nA typ to minimize divider error.

Key Specifications

Pinout & Package

RNA51958AP#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 plating, through-hole mount.

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, RNA51958AP#T0 uniquely supports both resistor-adjustable detection voltage (2–15 V) and capacitor-tunable delay (sub-ms to seconds), making it suitable for non-standard supply rails and timing-critical legacy DIP layouts where flexibility outweighs footprint constraints.

Availability

RNA51958AP#T0 is available at Aetrix Electronics and suitable for industrial control panels, battery-powered instrumentation, DC/DC converter sequencing, and legacy through-hole embedded systems requiring stable component supply and long-term obsolescence management.

Supply support for RNA51958AP#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 Japanese semiconductor manufacturer specializing in microcontrollers, analog, and power management ICs for industrial, automotive, and infrastructure applications.

The RNA51958A/B series was designed for robust, low-cost system reset in resource-constrained embedded systems - emphasizing external configurability, wide supply tolerance, and through-hole compatibility for maintenance and repair scenarios.

FAQ

What is the function of Pin 6 (Delay capacitor) on the RNA51958AP#T0?

Pin 6 provides a constant-current sink (~5 µA typ) that charges an external capacitor (Cd) to generate the reset delay time. The delay tpd ≈ 0.34 × Cd(pF) µs, allowing precise timing control using low-cost ceramic capacitors from 4700 pF to 10 µF. This eliminates need for internal oscillator or RC timing components in the RNA51958AP#T0.

Can RNA51958AP#T0 be used with a 3.3 V microcontroller supply?

Yes - RNA51958AP#T0 operates from 2 V to 17 V, so it functions reliably at 3.3 V. Its open-collector output (Pin 7) can drive a 3.3 V logic input when paired with a 3.3 V pull-up resistor. Detection voltage is set externally via resistor divider, enabling precise 3.3 V reset threshold (e.g., 3.3 V × R2/(R1+R2) = 1.25 V → R1/R2 ≈ 1.64).

What is the maximum recommended value for the external delay capacitor Cd on RNA51958AP#T0?

The datasheet specifies Cd ≤ 10 µF. Larger values cause increasing delay uncertainty (e.g., 100 µF yields 16–70 s variation), slower response to momentary voltage drops (tPHL increases to ~200 µs), and potential failure to achieve target delay due to insufficient capacitor discharge. For stable, predictable operation, use Cd between 4700 pF and 1 µF - e.g., 0.01 µF gives 3.4 ms typ delay.

How does the hysteresis of RNA51958AP#T0 improve system reliability?

RNA51958AP#T0 provides 15 mV typical hysteresis (ΔVS) between rising and falling detection thresholds. This prevents output chatter during slow or noisy supply ramps - for example, if VS = 1.25 V, the device releases reset at ~1.265 V but reasserts only below ~1.25 V. This eliminates false resets caused by ripple, load transients, or thermal drift in the RNA51958AP#T0's sensing path.

Is RNA51958AP#T0 RoHS compliant and lead-free?

Yes - RNA51958AP#T0 uses Ni/Pd/Au surface treatment (Package Code "0") and complies with EU RoHS Directive requirements. The DIP-8 package (PRDP0008AF-B) is lead-free and halogen-free, consistent with Renesas' environmental compliance documentation referenced in the datasheet colophon.