Renesas M51945BFP#DF1J

Overview

M51945BFP#DF1J from Renesas Electronics is an L-reset-type voltage-detecting system reset IC with open-collector output, designed for reliable power-on and brownout reset generation in microcomputer and logic circuits. It features a 1.25 V internal reference, ±15 mV hysteresis, 2–17 V supply range, and supports external resistor-based detection voltage setting from 2 V to 15 V. It is used in battery-check circuits, DC/DC converter supervision, and MCU reset applications.

For engineers reviewing the M51945BFP#DF1J datasheet, M51945BFP#DF1J pinout, M51945BFP#DF1J application, or M51945BFP#DF1J equivalent, key selection considerations include its open-collector output configuration, low 280 µA typical quiescent current at 5 V, –30°C to +85°C operating temperature range, and compatibility with standard 5-pin SIP packaging for space-constrained embedded designs.

Technical Context

The M51945BFP#DF1J 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 scaled voltage (via R1/R2 divider), triggering reset assertion when the input falls below the threshold. The open-collector output requires an external pull-up resistor and sinks up to 4 mA.

Unlike the built-in-load variant (M51945AFP), the BFP version provides design flexibility by decoupling output drive strength from internal circuitry-enabling interface with diverse logic families and voltage domains. Its propagation delay is ≤4 µs for H→L transitions and ≤2 µs for L→H transitions under nominal conditions.

Key Specifications

Pinout & Package

Package: 5-pin SIP (SIP5-P-240-2.54, EIAJ code 5P5T), plastic through-hole, 0.22 g mass, 11.9 mm × 2.54 mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M51945BFP#DF1J, TLV803EB29DBZR offers lower power but lacks programmability, while MAX6326UR29+T delivers tighter tolerance and push-pull drive but forfeits resistor-based threshold tuning-making M51945BFP#DF1J optimal where flexible, cost-effective, and robust reset configuration is prioritized.

Availability

M51945BFP#DF1J is available at Aetrix Electronics and suitable for battery-check circuits, MCU reset subsystems, and DC/DC converter supervision requiring stable component supply across extended product lifecycles.

Supply support for M51945BFP#DF1J 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 M51945BFP#DF1J belongs to Renesas' legacy Voltage Detecting, System Resetting IC Series, engineered for reliable, low-cost power-monitoring in resource-constrained embedded systems where external component count and long-term manufacturability are critical.

FAQ

What is the detection voltage accuracy of the M51945BFP#DF1J?

The M51945BFP#DF1J has a detection voltage of 1.25 V (typ), with a min/max range of 1.20 V to 1.30 V at 25°C. Its temperature coefficient is 0.01 %/°C, and hysteresis is 9–23 mV. Accuracy depends on external resistor tolerance and input current error (100 nA typ); for best results, use ≤1% resistors and keep R1+R2 ≤ 200 kΩ to limit error to <1%.

Can the M51945BFP#DF1J be used with a 3.3 V supply?

Yes, the M51945BFP#DF1J operates across 2 V to 17 V, making it fully compatible with 3.3 V systems. At 3.3 V, its typical circuit current is ~280 µA, and output saturation voltage remains ≤0.4 V at 4 mA sink. Ensure the external resistor divider scales the monitored voltage to ~1.25 V at the Input pin (Pin 2), respecting the input voltage limits: 0.8 V < VIN < 3.0 V for VCC = 3.3 V.

What does "BFP" signify in M51945BFP#DF1J?

The "B" denotes the open-collector output variant (vs. "A" for built-in load), "F" indicates the 5-pin SIP package (5P5T), and "P" specifies lead-free (Pb-free) plating. The full suffix "#DF1J" reflects Renesas' internal ordering and tape-and-reel packaging code; the device is RoHS-compliant and rated for industrial temperature operation (–30°C to +85°C).

How do I calculate the external resistor values for a 5.0 V reset threshold using M51945BFP#DF1J?

Use VS ≈ 1.25 × (R1 + R2)/R2. For VS = 5.0 V, rearrange to R1/R2 ≈ 3.0. Select R2 = 10 kΩ (1% metal film), then R1 = 30 kΩ. Verify input current error: at 100 nA, error = 100 nA × 30 kΩ = 3 mV (<0.1% of 5 V). Also confirm VIN at Pin 2 stays within 0.8–4.7 V (since VCC > 7 V not applicable here), which holds for this configuration.

Is the M51945BFP#DF1J recommended for new designs?

No - Renesas explicitly marks M51945BFP#DF1J as "Not recommend for new design" in its official documentation. While fully functional and supported for existing production, designers should evaluate modern alternatives (e.g., ISL88011, TPS3808G01) offering improved accuracy, lower quiescent current, smaller packages, and extended lifecycle assurance. Aetrix Electronics maintains inventory for legacy program continuity.