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Renesas M51946AL#TF0J
- Part No.:
- M51946AL#TF0J
- Manufacturer:
- Renesas
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
M51946AL#TF0J.pdf
- Description:
- IC SUPERVISOR VOLT DET SYS RESET
- Quantity:
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Inventory:22,721
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Product details
Overview
M51946AL#TF0J from Renesas Electronics is an H-type (high-active) voltage-detecting system reset IC with open-collector output, designed for reliable power-on and brownout reset generation in microcontroller and logic systems. It features a precise 1.25 V internal reference, ±15 mV hysteresis, 2–17 V supply range, and operates down to 0.55 V supply for functional reset assertion - used in embedded MCU reset circuits, battery-backed systems, and DC/DC converter supervision.
For engineers reviewing the M51946AL#TF0J datasheet, M51946AL#TF0J pinout, M51946AL#TF0J application, or M51946AL#TF0J equivalent, key selection criteria include its H-reset polarity, open-collector output configuration, external resistor-programmable detection threshold (1.25 × (R1+R2)/R2), low 280 µA typical quiescent current at 5 V, and compatibility with 8-pin SOP PRSP0008DE-C package for industrial temperature operation (–30°C to +85°C).
Technical Context
The M51946AL#TF0J implements a precision comparator architecture with a stable 1.25 V bandgap reference and 25 µA internal bias current. Its input stage monitors an externally divided supply voltage, triggering reset when input exceeds the threshold - enabling programmable detection from 2 V to 15 V via R1/R2 network.
As an H-reset device, it asserts a high-level output during normal operation and pulls low upon undervoltage condition. The open-collector output requires an external pull-up resistor (RL), supports sink currents up to 4 mA, and delivers <0.4 V saturation voltage at 4 mA - ensuring clean interface with TTL/CMOS logic inputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Detection Voltage | 1.25 V (typ), ±50 mV total tolerance - sets accurate reset threshold via external resistor divider |
| Hysteresis | 15 mV (typ) - prevents chatter during slow-rising/falling supply transitions |
| Supply Range | 2 V to 17 V - supports wide-input industrial and battery-powered systems |
| Reset Polarity | H-type (active-high normal, low on reset) - matches high-active reset inputs on MCUs like Renesas RL78 or older 78K families |
| Output Type | Open-collector - enables wired-OR reset buses and level translation across voltage domains |
| Quiescent Current | 280 µA (typ) at VCC = 5 V - enables low-power always-on supervision without significant battery drain |
| Propagation Delay | 2 µs (tPLH), 4 µs (tPHL) - ensures fast response to supply transients while avoiding noise-induced false triggers |
Pinout & Package
Package: 8-pin SOP (PRSP0008DE-C), recommended for new designs; RoHS-compliant plastic body, 4.4 mm × 4.85 mm footprint, 1.27 mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Output | Open-collector reset output - requires external pull-up; sinks up to 4 mA when reset asserted |
| 2 | Input | Voltage sense input - accepts divided supply; biased by 100 nA max input current |
| 3 | GND | Analog ground reference - must be low-impedance connection shared with system ground |
| 4 | Power-supply | VCC supply pin - powers internal comparator and reference; decoupling capacitor required |
| 5–8 | NC | No connection - internally unconnected; must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Externally programmable detection threshold | Settable from 2 V to 15 V using two resistors - eliminates need for multiple fixed-threshold parts |
| Low operating supply voltage | Functional down to 0.55 V (typ) - guarantees valid reset assertion even during deep brownout |
| Wide temperature range | –30°C to +85°C operation - qualified for industrial ambient environments without derating |
| Stable reference with low drift | 0.01 %/°C detecting voltage tempco - maintains threshold accuracy across operating range |
| Fast, noise-immune response | 2–4 µs propagation delay with built-in hysteresis - rejects sub-microsecond supply glitches |
Applications
| Microcontroller Power-On Reset | Battery Voltage Monitoring |
|---|---|
Use Scenario: Ensuring deterministic startup of an RL78/G13 MCU after power rail stabilization. IC Role / Device Role / Timing Role: Generates clean, glitch-free active-low reset pulse synchronized to VCC rise above 3.3 V threshold. Use Value: Prevents code execution before supply reaches valid logic levels - eliminates boot failures due to marginal VCC. |
Use Scenario: Supervising a 3.6 V Li-ion backup supply in a real-time clock module. IC Role / Device Role / Timing Role: Triggers system alert and disables non-critical peripherals when battery drops below 3.0 V. Use Value: Enables graceful shutdown and data retention using programmable 3.0 V threshold with <15 mV hysteresis. |
| DC/DC Converter Undervoltage Lockout | Industrial Logic System Reset |
Use Scenario: Enabling/disabling a 12 V → 5 V buck converter based on input rail health. IC Role / Device Role / Timing Role: Drives enable pin of converter IC via open-collector output with 10 kΩ pull-up to 12 V. Use Value: Provides precise 10.5 V turn-off threshold (via R1/R2) and prevents restart until input recovers by ≥15 mV. |
Use Scenario: Centralized reset coordination across multiple 74HC-series logic blocks in PLC I/O module. IC Role / Device Role / Timing Role: Single-point reset generator with wired-OR capability for multi-rail systems. Use Value: Eliminates need for discrete transistor reset networks - reduces BOM count and improves timing consistency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-detecting reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV803EB33DBZR | Fixed 3.3 V threshold, SOT-23-3, push-pull output, 1.8–6 V supply | Lacks programmability and wide supply range; no open-collector flexibility | Choose for space-constrained, fixed-threshold designs where board area > configurability |
| MAX6816EUS+T | 3.08 V fixed threshold, 8-pin SO, open-drain output, –40°C to +85°C, 1.5 µA IQ | Lower quiescent current but no external threshold adjustment; higher cost per unit | Prefer when ultra-low power dominates and 3.08 V matches system requirement exactly |
Compared with TLV803EB33DBZR and MAX6816EUS+T, the M51946AL#TF0J uniquely balances programmable threshold, industrial temperature support, open-collector drive, and proven legacy reliability - making it suitable for cost-sensitive, field-deployed equipment where design flexibility and long-term component availability matter.
Availability
M51946AL#TF0J is available at Aetrix Electronics and suitable for industrial control panels, battery-powered instrumentation, and legacy MCU-based embedded systems requiring stable component supply and long-lifecycle support.
Supply support for M51946AL#TF0J 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 M51946AL#TF0J belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series - engineered for robust, low-cost power supervision in resource-constrained embedded systems where reliability under variable supply conditions is critical.
FAQ
What is the reset polarity of the M51946AL#TF0J?
The M51946AL#TF0J is an H-type reset IC: its output remains high during normal operation and goes low when the sensed input voltage falls below the programmed threshold. This active-low reset signal directly interfaces with standard high-active reset inputs on Renesas 78K, RL78, and many third-party MCUs. The M51946AL#TF0J does not assert a high-level reset pulse - its function is strictly voltage-monitoring with open-collector sinking capability.
Can the M51946AL#TF0J detect voltages above 5 V?
Yes - the M51946AL#TF0J supports detection thresholds from 2 V to 15 V using an external resistor divider (R1/R2) on its Input pin. For example, with R1 = 24 kΩ and R2 = 10 kΩ, the detection voltage is approximately 1.25 × (24+10)/10 = 4.25 V. The device's 2–17 V supply range and input voltage rating (up to 7 V when VCC > 7 V) allow safe monitoring of higher rails like 12 V or 15 V systems when properly scaled.
What package is used for the M51946AL#TF0J?
The M51946AL#TF0J is supplied in the PRSP0008DE-C package: an 8-pin SOP (Small Outline Package) measuring 4.4 mm × 4.85 mm with 1.27 mm lead pitch. This is the recommended package per Renesas documentation - distinct from the obsolete PRSP0008DA-A (8P2S-A). The PRSP0008DE-C offers improved thermal performance (300 mW max power dissipation) and is RoHS-compliant.
Is the M51946AL#TF0J suitable for new designs?
Renesas explicitly labels the M51946AL#TF0J as "Not recommend for new design" in its official documentation due to product maturity and roadmap status. However, it remains fully supported, in active production, and widely used in industrial maintenance and legacy system refresh programs. Aetrix Electronics provides full supply chain continuity, including obsolescence mitigation and last-time-buy planning - making the M51946AL#TF0J viable for long-lifecycle deployments where redesign is impractical.
How do I calculate the required resistor values for a target detection voltage?
Use the formula VS ≈ 1.25 × (R1 + R2) / R2, where VS is the desired detection voltage. For instance, to set 4.0 V: 4.0 = 1.25 × (R1 + R2)/R2 → R1/R2 ≈ 2.2. Selecting R2 = 100 kΩ gives R1 = 220 kΩ. Account for input current error (≤500 nA) by keeping R1 + R2 ≤ 200 kΩ - the M51946AL#TF0J datasheet confirms this maintains <1% threshold error. Always verify final threshold with bench measurement under actual load conditions.
M51946AL#TF0J Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
M51946AL#TF0J FAQ
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6.How does Aetrix verify that M51946AL#TF0J is sourced from the original manufacturer or authorized distributors?
All M51946AL#TF0J 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 M51946AL#TF0J meets industry standards.
7.What is the process for return or replacement of M51946AL#TF0J?
All M51946AL#TF0J units undergo pre-shipment inspection (PSI). If there is an issue with M51946AL#TF0J, 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 M51946AL#TF0J part is unused and in its original packaging.
Return procedure for M51946AL#TF0J:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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