Texas Instruments LM809M3-4.63/NOPB

Overview

LM809M3-4.63/NOPB from Texas Instruments is a 3-pin SOT-23 microprocessor reset supervisor IC with a factory-programmed 4.63 V ±3% precision reset threshold, 240 ms typical reset timeout, and active-low open-drain RESET output. It monitors 5 V supply rails in embedded controllers and ensures reliable power-up/power-down reset assertion for industrial PLCs and factory automation systems.

For engineers reviewing the LM809M3-4.63/NOPB datasheet, LM809M3-4.63/NOPB pinout, LM809M3-4.63/NOPB application, or LM809M3-4.63/NOPB equivalent, key selection criteria include guaranteed reset validity down to VCC ≥1 V, 15 µA typical supply current, immunity to VCC transients ≤20 µs at 100 mV underthreshold, and full specification across –40°C to +105°C.

Technical Context

The LM809M3-4.63/NOPB implements a precision bandgap-based voltage comparator with internal hysteresis to detect VCC drops below 4.63 V. Its internal timer guarantees a minimum 140 ms (typical 240 ms) active-low RESET pulse after VCC recovers above threshold, meeting microprocessor reset timing requirements without external components.

Designed for direct integration into 5 V digital systems, it features ESD protection (±2000 V HBM), operates with VCC as low as 1.0 V while maintaining valid RESET output, and includes transient immunity circuitry that rejects sub-20 µs negative glitches on VCC-critical for noisy industrial power rails.

Key Specifications

Pinout & Package

LM809M3-4.63/NOPB uses the industry-standard 3-pin SOT-23 (DBZ) package, measuring 2.92 mm × 1.30 mm, with gull-wing leads optimized for automated surface-mount assembly and thermal performance (RθJA = 252°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor reset applications.

Compared with MAX809TRD3+T and TPS3808G33DBVR, LM809M3-4.63/NOPB delivers tighter threshold accuracy (±3% vs ±4.5% typical), longer guaranteed reset hold time, and proven industrial temperature stability-making it optimal for legacy 5 V controller upgrades where timing and voltage margin are critical.

Availability

LM809M3-4.63/NOPB is available at Aetrix Electronics and suitable for industrial PLCs, factory automation controllers, and renewable energy inverters requiring stable component supply with long-term lifecycle support.

Supply support for LM809M3-4.63/NOPB 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of experience in power management and system supervision ICs.

LM809M3-4.63/NOPB belongs to TI's microprocessor supervisory product line, engineered specifically for reliable reset generation in industrial, automotive, and computing applications where supply voltage integrity is mission-critical.

FAQ

What is the exact reset threshold voltage of LM809M3-4.63/NOPB and how does it vary with temperature?

The LM809M3-4.63/NOPB has a factory-trimmed reset threshold of 4.63 V with ±3% tolerance at 25°C. Over the full operating range (–40°C to +105°C), the threshold shifts by ≤±0.12 V (30 ppm/°C), remaining within 4.40 V to 4.86 V. This ensures consistent 5 V supply monitoring without recalibration across industrial environments.

Does LM809M3-4.63/NOPB require external components to function correctly?

No, LM809M3-4.63/NOPB operates autonomously with only VCC, GND, and RESET connections. However, a pull-up resistor (typically 10 kΩ to 100 kΩ) is required on the open-drain RESET pin to establish a defined high state. A 0.1 µF bypass capacitor on VCC is recommended to suppress high-frequency noise that could cause false resets.

Can LM809M3-4.63/NOPB be used with microcontrollers that have bidirectional reset pins?

Yes, LM809M3-4.63/NOPB can interface with bidirectional reset pins (e.g., Motorola 68HC11) using a 4.7 kΩ series resistor between RESET and the MCU pin. This prevents contention when the MCU drives the pin low while LM809M3-4.63/NOPB asserts active-low reset, ensuring safe, conflict-free operation.

What is the minimum VCC voltage at which LM809M3-4.63/NOPB guarantees valid RESET output?

LM809M3-4.63/NOPB guarantees valid RESET output down to VCC = 1.0 V across the full temperature range. Below 1 V, the internal comparator ceases operation and RESET enters high-impedance state-so systems requiring reset assertion below 1 V must add an external pull-down resistor (e.g., 100 kΩ to GND) per TI application guidance.

How does LM809M3-4.63/NOPB handle fast transients on the VCC supply line?

LM809M3-4.63/NOPB rejects negative-going VCC transients ≤20 µs in duration when they dip up to 100 mV below the 4.63 V threshold. This immunity is built-in and does not require external filtering-though adding a 0.1 µF ceramic capacitor near the VCC pin further enhances noise rejection for high-dv/dt environments like motor drives.