Renesas M51946BL#TF0J

Overview

M51946BL#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 brown-out reset generation in microcontroller and logic systems. It features a precise 1.25 V internal reference, 15 mV typical hysteresis, wide 2–17 V supply range, and operates down to 0.55 V supply voltage. Used in embedded reset circuits where external resistor programming enables custom detection thresholds from 2 V to 15 V.

For engineers reviewing the M51946BL#TF0J datasheet, M51946BL#TF0J pinout, M51946BL#TF0J application, or M51946BL#TF0J equivalent, key selection criteria include its open-collector output configuration, −30°C to +85°C operating temperature, 5-pin SIP package, low 280 µA typical circuit current at 5 V, and compatibility with both CMOS and TTL logic interfaces.

Technical Context

The M51946BL#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 a high-level reset output when the monitored voltage exceeds the threshold.

Unlike L-type variants (e.g., M51945), the M51946BL#TF0J asserts RESET high upon valid supply conditions - making it suitable for processors requiring active-high reset assertion. The open-collector output allows flexible pull-up voltage selection up to 17 V and supports wired-OR configurations.

Key Specifications

Pinout & Package

Package: 5-pin SIP (SIP5-P-240-2.54 / 5P5T), 11.9 mm × 2.54 mm footprint, plastic body, lead-free (Pb-free) per RoHS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV803EB29DBZR and MAX6326UR29+T, the M51946BL#TF0J uniquely supports user-defined detection thresholds across 2–15 V using two resistors, operates up to 17 V supply, and maintains full functionality down to −30°C - making it suitable for industrial and multi-rail applications where flexibility and ruggedness are critical.

Availability

M51946BL#TF0J is available at Aetrix Electronics and suitable for microcontroller reset circuits, battery monitoring systems, and industrial logic supervision requiring stable component supply across extended temperature and voltage ranges.

Supply support for M51946BL#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 delivering microcontrollers, analog, power, and SoC solutions for automotive, industrial, and enterprise applications.

The M51946BL#TF0J belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series - designed specifically for robust, low-cost, externally programmable reset generation in resource-constrained embedded systems.

FAQ

What is the function of the NC pin on the M51946BL#TF0J?

The NC (No Connection) pin on the M51946BL#TF0J is internally unconnected and serves no electrical function. It must be left floating or tied to GND per layout best practices; connecting it to VCC or driving it may cause unpredictable behavior. This pin exists for mechanical compatibility within the 5-pin SIP package family and does not affect M51946BL#TF0J operation.

How do I calculate the detection voltage for the M51946BL#TF0J?

The detection voltage VS for the M51946BL#TF0J is calculated as VS ≈ 1.25 V × (R1 + R2)/R2, where R1 connects between VCC and the Input pin (Pin 2), and R2 connects between Input and GND. For accuracy, keep total resistance ≤ 100 kΩ to minimize error from input current (100 nA typ). Example: R1 = 18 kΩ, R2 = 2.2 kΩ yields VS ≈ 11.5 V. This formula applies directly to M51946BL#TF0J.

Is the M51946BL#TF0J pin-compatible with the M51946AL?

Yes - the M51946BL#TF0J and M51946AL share identical pinout, electrical specifications, and functional behavior. Both are H-type open-collector reset ICs in 5-pin SIP packages. The "B" suffix denotes open-collector output (vs. "A" for built-in load), and "L" indicates the PRSP0008DE-C–compatible lead form. M51946BL#TF0J is the RoHS-compliant, tape-and-reel packaged version of the same die used in M51946AL.

What is the maximum allowable output sink current for the M51946BL#TF0J?

The absolute maximum output sink current for the M51946BL#TF0J is 6 mA, but the recommended operating limit is 4 mA to ensure reliable saturation voltage (Vsat ≤ 0.4 V) and thermal stability. Exceeding 4 mA continuously increases junction temperature and may degrade long-term reliability. Always verify pull-up resistor value (RL) satisfies IL = (VPU − Vsat)/RL ≤ 4 mA, where VPU is pull-up voltage (≤17 V).

Does the M51946BL#TF0J support operation below 2 V supply?

No - the M51946BL#TF0J has a specified minimum supply voltage of 2 V per its Recommended Operating Conditions and Absolute Maximum Ratings. While the threshold operating voltage (VOPL) is 0.55 V (typical), this refers to the lowest VCC at which the internal circuit remains functional *once powered*, not the minimum voltage for initial power-up. Below 2 V, the M51946BL#TF0J cannot guarantee correct detection or output behavior and must not be operated.