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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Supervisors

Renesas RNA51957BP#T0

Name: RNA51957BP#T0
Brand: Renesas
SKU: RNA51957BP#T0
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: RNA51957BP#T0

Manufacturer:: Renesas

Category:: Supervisors

Package:: 8-DIP (0.300", 7.62mm)

Datasheet:: RNA51957BP#T0.pdf

Description:: IC SUPERVISOR 1 CHANNEL 8DIP

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Product details

Overview

RNA51957BP#T0 from Renesas Electronics is a voltage-detecting system reset IC with open-collector output (Type B), designed for reliable power-on and brownout reset generation in microcontrollers and logic circuits. It features a 1.25 V (typ) detection threshold, 2–17 V supply range, and external capacitor-programmable delay up to ~100 ms (at 0.33 µF). Used in battery-check and level-detect circuits where low-threshold operation and flexible timing are required.

For engineers reviewing the RNA51957BP#T0 datasheet, RNA51957BP#T0 pinout, RNA51957BP#T0 application, or RNA51957BP#T0 equivalent, key selection criteria include its L-reset behavior, open-collector output compatibility with external pull-up resistors, wide V_CC range, temperature-stable detection voltage (±0.01%/°C), and ability to set detection voltage via external resistor divider.

Technical Context

The RNA51957BP#T0 implements an internal comparator with 1.25 V reference and hysteresis (9–23 mV), enabling stable voltage monitoring under noisy conditions. Its open-collector output supports flexible interfacing with diverse logic families and voltage domains via external pull-up.

A dedicated delay capacitor terminal (Cd) draws a constant current (~–5 µA typ) to generate precise RC-based timing; delay time follows t_pd ≈ 0.34 × C_d(pF) µs. The IC operates down to 0.55 V (typ) supply-critical for low-voltage battery backup scenarios-and tolerates input voltages up to 7.0 V independent of V_CC.

Key Specifications

Parameter	Value and Actual Design Meaning
Detection Voltage	1.25 V (typ); sets reset trigger point via external R1/R2 divider; enables custom supply monitoring from 2–15 V.
Supply Range	2 V to 17 V; supports wide-input systems including 3.3 V, 5 V, and 12 V rails without external regulation.
Output Type	Open-collector (Type B); requires external pull-up; allows level-shifting and wired-OR reset bus configurations.
Delay Time	1.6–7.0 ms (at C_d = 0.01 µF); scalable to ~100 ms with 0.33 µF; enables precise power-up sequencing control.
Hysteresis	9–23 mV; prevents chatter during slow-rising/falling supply edges; ensures clean, glitch-free reset assertion.
Threshold Operating Voltage	0.55 V (typ) at R_L = 100 kΩ; maintains functional reset capability even during deep brownout or battery depletion.
Input Current	100 nA (typ); minimizes error in resistor-divider-based detection voltage setting; supports high-impedance sensing.

Pinout & Package

RNA51957BP#T0 is housed in an 8-pin DIP package (PRDP0008AF-B), with 2.54 mm lead pitch, Ni/Pd/Au plating, and 0.54 g typical mass. Pin 1 is marked by a notch or dot; top-view orientation matches standard DIP layout.

Pin/Terminal	Circuit Role	Design Meaning
1	NC	No connection; electrically isolated; must remain unconnected per datasheet.
2	Input	Voltage sense input; accepts partial V_CC from R1/R2 divider; max 7.0 V when V_CC > 7 V.
3	GND	Ground reference for internal circuitry and output sink path; must connect to system ground plane.
4	NC	No connection; electrically isolated; must remain unconnected.
5	NC	No connection; electrically isolated; must remain unconnected.
6	Delay capacitor	Constant-current sink (~–5 µA); sets reset delay time via external capacitor (4700 pF–10 µF).
7	Output	Open-collector NPN output; sinks up to 4 mA; requires external pull-up resistor for logic-high state.
8	Power-supply	V_CC input; powers internal circuitry; valid from 2–17 V; decoupling capacitor recommended.

Key Features

Feature	Design Value
Externally programmable detection voltage	Set via R1/R2 divider; enables monitoring of any supply rail between 2 V and 15 V without redesign.
Capacitor-tunable reset delay	Delay scales linearly with Cd (t_pd ≈ 0.34 × C_d(pF) µs); achieves 100 ms with only 0.33 µF-no timing IC or crystal needed.
Ultra-low operating voltage	Functional down to 0.55 V (typ); ensures reset remains active during severe brownout or battery sag below 1 V.
Open-collector output architecture	Supports mixed-voltage systems; enables shared reset buses; eliminates need for level translators or buffer ICs.
Low input bias current	100 nA (typ); reduces voltage divider loading error; permits use of high-value resistors for low quiescent power.

Applications

Battery Backup Monitoring	Microcontroller Power-On Reset
Use Scenario: Monitoring lithium coin-cell or alkaline battery voltage during system sleep to initiate graceful shutdown before depletion. IC Role / Device Role / Timing Role: Voltage detector and delayed reset generator; asserts reset when battery drops below 2.4 V (set via R1/R2), with 50 ms hold time. Use Value: Prevents data corruption or undefined MCU states during low-battery operation; delay ensures stable power reassertion before release.	Use Scenario: Ensuring reliable initialization of an ARM Cortex-M0+ MCU after 3.3 V rail stabilizes post-power-up. IC Role / Device Role / Timing Role: L-reset supervisor; monitors 3.3 V rail and holds RESET# low for ≥100 ms until voltage exceeds 3.1 V. Use Value: Guarantees sufficient clock stabilization and internal register initialization before firmware execution begins.
DC/DC Converter Sequencing	Level-Detecting Waveform Shaping
Use Scenario: Controlling startup order of dual-output DC/DC converters (e.g., 5 V → 1.2 V) in FPGA power systems. IC Role / Device Role / Timing Role: Delayed enable signal generator; triggers secondary converter only after primary rail reaches regulation. Use Value: Eliminates need for discrete RC timers or dedicated sequencer ICs; reduces BOM count and layout area.	Use Scenario: Converting noisy analog sensor outputs (e.g., thermistor voltage) into clean digital logic pulses for microcontroller input. IC Role / Device Role / Timing Role: Hysteresis-based comparator and delay element; filters noise and adds debouncing interval. Use Value: Replaces op-amp + timer combinations; provides built-in 15 mV hysteresis and adjustable delay without external components.

Battery Backup Monitoring

Microcontroller Power-On Reset

Use Scenario: Monitoring lithium coin-cell or alkaline battery voltage during system sleep to initiate graceful shutdown before depletion.

IC Role / Device Role / Timing Role: Voltage detector and delayed reset generator; asserts reset when battery drops below 2.4 V (set via R1/R2), with 50 ms hold time.

Use Value: Prevents data corruption or undefined MCU states during low-battery operation; delay ensures stable power reassertion before release.

Use Scenario: Ensuring reliable initialization of an ARM Cortex-M0+ MCU after 3.3 V rail stabilizes post-power-up.

IC Role / Device Role / Timing Role: L-reset supervisor; monitors 3.3 V rail and holds RESET# low for ≥100 ms until voltage exceeds 3.1 V.

Use Value: Guarantees sufficient clock stabilization and internal register initialization before firmware execution begins.

DC/DC Converter Sequencing

Level-Detecting Waveform Shaping

Use Scenario: Controlling startup order of dual-output DC/DC converters (e.g., 5 V → 1.2 V) in FPGA power systems.

IC Role / Device Role / Timing Role: Delayed enable signal generator; triggers secondary converter only after primary rail reaches regulation.

Use Value: Eliminates need for discrete RC timers or dedicated sequencer ICs; reduces BOM count and layout area.

Use Scenario: Converting noisy analog sensor outputs (e.g., thermistor voltage) into clean digital logic pulses for microcontroller input.

IC Role / Device Role / Timing Role: Hysteresis-based comparator and delay element; filters noise and adds debouncing interval.

Use Value: Replaces op-amp + timer combinations; provides built-in 15 mV hysteresis and adjustable delay without external components.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TLV803DBZQ1	Fixed 3.08 V detection; no external resistor programming; SOT-23-3 package; 140 ms min delay (internal).	Suitable for fixed-rail systems only; lacks flexibility for custom thresholds or multi-rail monitoring.	Choose when board space is critical and detection voltage matches standard rails (e.g., 3.3 V).
MAX809SEUR+T	Fixed 3.08 V detection; push-pull output; 140 ms min delay; 5-pin SOT-23 package.	Requires no external pull-up; incompatible with wired-OR reset buses; limited to single-voltage monitoring.	Prefer when driving CMOS inputs directly and avoiding external resistors; not suitable for mixed-voltage reset buses.

Compared with TLV803DBZQ1 and MAX809SEUR+T, RNA51957BP#T0 uniquely supports user-defined detection thresholds across 2–15 V, open-collector output for bus sharing, and capacitor-adjustable delay-making it optimal for multi-rail, space-tolerant, and battery-sensitive designs where flexibility outweighs ultra-small footprint needs.

Availability

RNA51957BP#T0 is available at Aetrix Electronics and suitable for battery-check circuits, microcontroller reset supervision, and DC/DC converter sequencing requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for RNA51957BP#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 delivering microcontrollers, analog, power, and SoC solutions for automotive, industrial, and IoT applications.

The RNA51957 series belongs to Renesas' voltage supervisor product line, engineered specifically for cost-sensitive, high-reliability reset and brownout protection in resource-constrained embedded systems.

FAQ

What is the detection voltage accuracy and temperature stability of RNA51957BP#T0?

RNA51957BP#T0 has a detection voltage of 1.25 V (typ), with min/max values of 1.20 V and 1.30 V at 25°C. Its temperature coefficient is 0.01%/°C, meaning detection voltage drift is ±0.08% over –40°C to +85°C. This ensures consistent reset behavior across industrial temperature ranges without calibration.

Can RNA51957BP#T0 monitor a 12 V supply rail?

Yes. RNA51957BP#T0 supports supply voltages up to 17 V and allows detection voltage to be set between 2 V and 15 V using an external resistor divider on the Input pin (Pin 2). For a 12 V rail, configure R1/R2 so that (R1 + R2)/R2 × 1.25 V ≈ 12 V-e.g., R1 = 86 kΩ, R2 = 12 kΩ yields ~10.2 V detection, easily adjusted for exact threshold.

What is the maximum delay capacitance supported by RNA51957BP#T0?

RNA51957BP#T0 specifies a recommended delay capacitor range of 4700 pF to 10 µF. While larger values (e.g., 100 µF) may yield longer delays (up to ~34 s), they introduce significant timing variation (±100%), slower response to momentary dips, and potential failure to achieve target delay-so 10 µF is the practical upper limit for reliable operation.

How does the open-collector output of RNA51957BP#T0 interface with a 1.8 V microcontroller?

RNA51957BP#T0's open-collector Output (Pin 7) can drive a 1.8 V MCU by using a pull-up resistor to the MCU's 1.8 V supply. Since the output sinks current rather than sourcing it, logic-low is guaranteed at ≤0.4 V (at 4 mA), and logic-high equals the pull-up voltage-enabling safe, level-shifted reset signaling without additional buffers.

Is RNA51957BP#T0 suitable for automotive applications?

RNA51957BP#T0 is rated for –40°C to +85°C operation and meets Renesas' "Standard" quality grade, intended for industrial, computing, and consumer equipment-not safety-critical automotive systems. For AEC-Q100 qualified alternatives, consult Renesas' ISL801xx or RAJ series supervisors.

RNA51957BP#T0 Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: -

Package/Case:: 8-DIP (0.300", 7.62mm)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

Type:: Simple Reset/Power-On Reset

Number of Voltages Monitored:: 1

Voltage - Threshold:: 1.25V

Output:: Open Drain or Open Collector

Reset:: Active Low

Reset Timeout:: Adjustable/Selectable

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 8-DIP

RNA51957BP#T0 FAQ

1.How can I place an order for RNA51957BP#T0 through Aetrix?

Please submit a Request for Quotation (RFQ) for RNA51957BP#T0 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for RNA51957BP#T0 reliable?

The price and inventory of RNA51957BP#T0 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for RNA51957BP#T0 is usually 5 days.

3.What payment methods are accepted for RNA51957BP#T0?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for RNA51957BP#T0 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for RNA51957BP#T0?

RNA51957BP#T0 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your RNA51957BP#T0 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for RNA51957BP#T0?

For technical support, including RNA51957BP#T0 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your RNA51957BP#T0 requirements.

6.How does Aetrix verify that RNA51957BP#T0 is sourced from the original manufacturer or authorized distributors?

All RNA51957BP#T0 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that RNA51957BP#T0 meets industry standards.

7.What is the process for return or replacement of RNA51957BP#T0?

All RNA51957BP#T0 units undergo pre-shipment inspection (PSI). If there is an issue with RNA51957BP#T0, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The RNA51957BP#T0 part is unused and in its original packaging.

Return procedure for RNA51957BP#T0:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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