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Renesas RNA51957BFP#H0
- Part No.:
- RNA51957BFP#H0
- Manufacturer:
- Renesas
- Category:
- Supervisors
- Package:
- 8-SOIC (0.173", 4.40mm Width)
- Datasheet:
-
RNA51957BFP#H0.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,818
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Product details
Overview
RNA51957BFP#H0 from Renesas Electronics is a voltage-detecting system reset IC with L-type (active-low) reset output, designed for microcontroller and logic circuit supervision. It features a 1.25 V (typ) detection threshold, 2–17 V supply range, open-collector output, and external capacitor-programmable delay up to ~100 ms (e.g., 0.33 μF). It is used in CPU reset circuits, battery-check systems, and DC/DC converter monitoring.
For engineers reviewing the RNA51957BFP#H0 datasheet, RNA51957BFP#H0 pinout, RNA51957BFP#H0 application, or RNA51957BFP#H0 equivalent, key selection criteria include its open-collector output configuration, external resistor-settable detection voltage (VS × (R1+R2)/R2), capacitor-defined delay time (td ≈ 0.34 × Cd(pF) μs), and operation down to 0.55 V supply (typ) for low-voltage brownout detection.
Technical Context
The RNA51957BFP#H0 implements a precision bandgap-based voltage comparator with 15 mV (typ) hysteresis and a constant-current sink (~5 μA typ) at the delay capacitor (Cd) pin to enable accurate RC timing. Its input stage accepts externally divided supply voltage or independent signals within –0.3 V to +7 V (for VCC > 7 V), supporting flexible reset source configurations beyond VCC monitoring.
As an "L reset type" device, it asserts a low-level reset signal when input voltage falls below the threshold and holds it for a user-defined delay after recovery. The open-collector output requires an external pull-up resistor (RL), enabling level-shifting and wired-OR capability across multiple reset sources in complex power-up sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Detection Voltage (VS) | 1.25 V (typ); sets reset threshold via external resistor divider - enables custom detection from 2 V to 15 V |
| Hysteresis Voltage (ΔVS) | 15 mV (typ); prevents chatter during slow-rising/falling supply edges - ensures clean reset release |
| Supply Voltage Range | 2 V to 17 V; supports wide-input industrial and automotive subsystems without external regulators |
| Delay Time (tpd) | 3.4 ms (typ) at Cd = 0.01 μF; scales linearly with capacitance - 0.34 × Cd(pF) μs enables precise timing from μs to seconds |
| Threshold Operating Voltage (VOPL) | 0.55 V (typ) at RL = 100 kΩ; guarantees internal functionality even during deep brownout - critical for fail-safe shutdown |
| Output Type | Open-collector; allows flexible pull-up voltage selection (2–17 V) and multi-source reset bus wiring |
| Input Current (IIN) | 100 nA (typ); minimizes resistor-divider loading error - enables high-impedance sensing without accuracy loss |
Pinout & Package
RNA51957BFP#H0 is housed in an SOP-8 package (JEITA PRSP0008DE-C, Renesas code FP), measuring 4.85 mm × 6.2 mm × 1.42 mm with 1.27 mm pitch, Ni/Pd/Au surface finish, and tape-and-reel packaging (2,500 pcs/reel).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | No Connection | Internally unconnected - must be left floating or tied to GND; no electrical function |
| 2 | Input | Voltage sense node - accepts divided VCC or external signal; operates within –0.3 V to +7 V (VCC > 7 V) |
| 3 | GND | Analog/digital ground reference - must be low-impedance connection to system common ground plane |
| 4 | Power-supply (VCC) | Main supply input - powers internal circuitry; valid from 2 V to 17 V; bypass capacitor required |
| 5 | NC | No Connection - internally unconnected; leave unconnected or tie to GND per layout best practice |
| 6 | Delay capacitor (Cd) | Constant-current sink (~5 μA typ) - sets delay time via external capacitor (4700 pF to 10 μF) |
| 7 | NC | No Connection - internally unconnected; no routing or termination required |
| 8 | Output | Open-collector reset output - sinks current when active (low); requires external pull-up resistor (RL) |
Key Features
| Feature | Design Value |
|---|---|
| Externally programmable detection voltage | Set via two-resistor divider - eliminates need for fixed-threshold variants and reduces BOM count |
| Capacitor-tunable delay with low-current sink | 5 μA typ Cd-pin current enables stable timing with small, low-cost ceramic capacitors (no electrolytics needed) |
| Ultra-low threshold operating voltage | 0.55 V (typ) minimum VCC for operation - ensures reliable reset assertion during severe undervoltage conditions |
| Wide supply range with no external bias | 2–17 V operation without auxiliary supplies - simplifies design for multi-rail systems and battery-powered devices |
| Open-collector output with 18 V abs max rating | Supports pull-up to any rail ≤17 V - enables reset coordination across mixed-voltage domains (e.g., 3.3 V logic + 12 V analog) |
Applications
| Microcontroller Power-Up Sequencing | Battery Voltage Monitoring |
|---|---|
Use Scenario: Ensuring stable initialization of an ARM Cortex-M4 MCU after Li-ion battery discharge reaches 3.0 V. IC Role / Device Role / Timing Role: Voltage detector and delayed reset generator - monitors battery voltage via resistor divider and holds reset until post-brownout stabilization. Use Value: Prevents MCU lockup by enforcing ≥100 ms reset hold time after voltage recovery, using only a 0.33 μF capacitor and two resistors. |
Use Scenario: Detecting end-of-life voltage drop in a 4-cell NiMH pack (4.8 V nominal) powering portable medical instrumentation. IC Role / Device Role / Timing Role: Low-voltage warning and graceful shutdown trigger - asserts reset at 4.2 V with 50 ms delay to initiate data save before cutoff. Use Value: Achieves ±2% detection accuracy over –40°C to +85°C using internal 15 mV hysteresis, eliminating calibration overhead. |
| DC/DC Converter Fault Protection | Industrial PLC Input Conditioning |
Use Scenario: Monitoring output voltage of an isolated 24 V → 5 V DC/DC converter in factory automation equipment. IC Role / Device Role / Timing Role: Secondary-side supervisor - detects converter dropout and initiates controlled system reset without relying on primary-side feedback. Use Value: Operates directly from 5 V rail with 0.55 V min VCC, ensuring reset remains active even during partial converter failure. |
Use Scenario: Debouncing and timing synchronization of 24 V digital inputs in a DIN-rail mounted PLC module. IC Role / Device Role / Timing Role: Waveform shaper and delay generator - converts noisy field switch signals into clean, glitch-free reset pulses with adjustable duration. Use Value: Uses open-collector output to interface directly with 24 V logic rails and leverages Cd pin for precise 1–500 ms delays without microcontroller intervention. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-detecting reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV809E33DBZR | Fixed 3.3 V detection; no external resistor programming; push-pull output; 140 ms fixed delay | Lacks adjustable threshold and capacitor-tunable delay - suitable only for fixed-rail designs | Choose when system uses only 3.3 V logic and requires minimal external components |
| MAX809TRD3+ | Fixed 3.08 V detection; push-pull output; 140 ms fixed delay; higher quiescent current (20 μA) | No external timing or threshold adjustment - limited to standard supply rails | Select for legacy compatibility in cost-sensitive consumer electronics where flexibility is not required |
Compared with TLV809E33DBZR and MAX809TRD3+, RNA51957BFP#H0 provides design flexibility through resistor-settable detection and capacitor-defined delay, enabling single-BOM support across multiple voltage rails and timing requirements - reducing variant proliferation and qualification effort.
Availability
RNA51957BFP#H0 is available at Aetrix Electronics and suitable for microcontroller reset circuits, battery-check systems, and DC/DC converter supervision requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.
Supply support for RNA51957BFP#H0 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, power, and timing solutions for industrial, automotive, and enterprise applications.
RNA51957BFP#H0 belongs to Renesas' Voltage Detecting, System Resetting IC Series - engineered for robust, configurable power-supply monitoring in resource-constrained embedded systems where flexibility and reliability are critical.
FAQ
What is the detection voltage accuracy and temperature drift of RNA51957BFP#H0?
RNA51957BFP#H0 has a detection voltage (VS) 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 VS varies by ±0.01% per °C change - resulting in ±0.125 V drift over –40°C to +85°C. This stability is confirmed in the Typical Characteristics graph on page 5 of the datasheet, showing VS variation < ±15 mV across temperature.
Can RNA51957BFP#H0 monitor a voltage source independent of its own VCC supply?
Yes, RNA51957BFP#H0 supports independent input monitoring: its Input pin (pin 2) accepts signals from –0.3 V to +7 V (when VCC > 7 V) or –0.3 V to VCC (when VCC ≤ 7 V), decoupled from the VCC rail. This enables use cases like monitoring a 12 V battery while powered from a separate 5 V rail - as shown in Figure 2(b) of the datasheet.
What is the maximum recommended value for the delay capacitor Cd in RNA51957BFP#H0?
The datasheet specifies Cd must be ≤ 10 μF. Larger values cause three issues: (1) increased delay time variation (e.g., 100 μF yields 16–70 s instead of nominal 34 s), (2) degraded response to momentary dips (tPHL increases to ~200 μs), and (3) incomplete discharge leading to inaccurate timing. For stable operation, Cd should be between 4700 pF and 10 μF - with 0.01–1 μF recommended for most designs.
How does the open-collector output of RNA51957BFP#H0 affect pull-up resistor selection?
RNA51957BFP#H0's open-collector output requires an external pull-up resistor (RL). To keep output saturation voltage ≤ 0.4 V at 4 mA sink, RL must be chosen so IL ≤ 4 mA. For example, with a 5 V pull-up, RL ≥ 1.25 kΩ; with 12 V, RL ≥ 3 kΩ. Absolute max sink current is 6 mA - exceeding this risks damage. RL values from 2.2 kΩ to 100 kΩ are commonly used.
Is RNA51957BFP#H0 qualified for automotive applications?
RNA51957BFP#H0 is rated for –40°C to +85°C operating temperature and classified as "Standard" grade per Renesas' quality policy - intended for industrial, office, and communications equipment. It is not qualified for automotive (AEC-Q100) or safety-critical applications. For automotive use, Renesas offers dedicated automotive-grade reset ICs such as the R3112x series.
RNA51957BFP#H0 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 8-SOIC (0.173", 4.40mm Width)
- 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:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
RNA51957BFP#H0 FAQ
1.How can I place an order for RNA51957BFP#H0 through Aetrix?
Please submit a Request for Quotation (RFQ) for RNA51957BFP#H0 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 RNA51957BFP#H0 reliable?
The price and inventory of RNA51957BFP#H0 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for RNA51957BFP#H0 is usually 5 days.
3.What payment methods are accepted for RNA51957BFP#H0?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for RNA51957BFP#H0 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for RNA51957BFP#H0?
RNA51957BFP#H0 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your RNA51957BFP#H0 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 RNA51957BFP#H0?
For technical support, including RNA51957BFP#H0 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your RNA51957BFP#H0 requirements.
6.How does Aetrix verify that RNA51957BFP#H0 is sourced from the original manufacturer or authorized distributors?
All RNA51957BFP#H0 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 RNA51957BFP#H0 meets industry standards.
7.What is the process for return or replacement of RNA51957BFP#H0?
All RNA51957BFP#H0 units undergo pre-shipment inspection (PSI). If there is an issue with RNA51957BFP#H0, 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 RNA51957BFP#H0 part is unused and in its original packaging.
Return procedure for RNA51957BFP#H0:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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