Texas Instruments LM810M3-4.38/NOPB

Overview

LM810M3-4.38/NOPB from Texas Instruments is a 3-pin SOT-23 active-high microprocessor reset supervisor IC designed for precision V_CC monitoring in embedded digital systems. It asserts a high-level RESET signal when supply voltage falls below 4.38 V (±3% over temperature), holds reset for 240 ms after recovery, operates down to V_CC ≥ 1 V, draws only 15 µA typical supply current, and supports industrial temperature range (–40°C to +105°C). It is used in programmable logic controllers during cold-start sequencing to ensure deterministic firmware initialization.

For engineers reviewing the LM810M3-4.38/NOPB datasheet, LM810M3-4.38/NOPB pinout, LM810M3-4.38/NOPB application, or LM810M3-4.38/NOPB equivalent, key selection criteria include reset threshold accuracy (4.38 V ±3%), active-high output polarity, guaranteed reset assertion at V_CC ≥ 1 V, 240-ms timeout stability across temperature, and SOT-23 footprint compatibility with space-constrained industrial control modules.

Technical Context

The LM810M3-4.38/NOPB implements a factory-trimmed bandgap-based voltage comparator with hysteresis to detect V_CC droop below its 4.38-V threshold. Its internal timing circuit generates a fixed 240-ms reset pulse width after V_CC recovers above threshold, independent of external components.

This device operates as a standalone power-on reset (POR) and brown-out detection (BOD) element, requiring no external capacitors or resistors. Its active-high RESET output directly interfaces with microcontroller reset inputs rated for 5-V tolerant logic, and its 15-µA quiescent current enables use in battery-backed systems where leakage must be minimized.

Key Specifications

Pinout & Package

SOT-23 (DBZ) package, 3-pin, body size 2.92 mm × 1.30 mm, surface-mount, RoHS-compliant tin (SN) lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX810LUR43D+T and TPS3808G33DBVR, the LM810M3-4.38/NOPB provides tighter threshold accuracy (±3% vs. ±4%) and longer guaranteed timeout (140–560 ms vs. 200 ms min) for 5-V systems, while maintaining pin compatibility and minimal bill-of-materials impact.

Availability

LM810M3-4.38/NOPB is available at Aetrix Electronics and suitable for industrial automation, renewable energy inverters, and factory sensor networks requiring stable component supply with full lifecycle support and traceable sourcing.

Supply support for LM810M3-4.38/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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets since 1930.

The LM810 series belongs to TI's microprocessor supervisory IC product line, engineered specifically for deterministic power-on and brown-out reset generation in resource-constrained embedded systems without external timing components.

FAQ

What is the exact reset threshold voltage of the LM810M3-4.38/NOPB and how does it vary with temperature?

The LM810M3-4.38/NOPB has a factory-programmed reset threshold of 4.38 V with ±3% tolerance over the full operating temperature range (–40°C to +105°C). At 25°C, the typical value is 4.38 V (min 4.31 V, max 4.45 V); at –40°C to +85°C, it remains within 4.25 V to 4.50 V; and at +85°C to +105°C, it shifts to 4.16 V to 4.56 V. This tight tolerance ensures consistent behavior across thermal stress conditions in industrial environments.

Does the LM810M3-4.38/NOPB require an external pull-up resistor on the RESET pin?

Yes - the LM810M3-4.38/NOPB features an open-drain active-high RESET output. To ensure a valid high logic level when not asserted, a pull-up resistor to V_CC is required. Texas Instruments recommends a 10-kΩ to 100-kΩ resistor depending on bus capacitance and rise-time requirements. Without this resistor, the RESET pin floats high-impedance during inactive state, risking undefined logic levels.

Can the LM810M3-4.38/NOPB operate reliably when V_CC drops below 1 V?

No - the LM810M3-4.38/NOPB guarantees valid RESET output only for V_CC ≥ 1 V. Below 1 V, the internal circuitry cannot maintain defined output states. For applications requiring reset assertion down to 0 V, TI recommends adding a 100-kΩ pull-down resistor on the RESET pin (for LM809) or a 100-kΩ pull-up (for LM810) to prevent floating, though output validity is not assured below 1 V per datasheet specifications.

What is the minimum power-on reset pulse width guaranteed by the LM810M3-4.38/NOPB?

The LM810M3-4.38/NOPB guarantees a minimum reset pulse width of 140 ms over –40°C to +85°C, with a typical value of 240 ms. At elevated temperatures (+85°C to +105°C), the minimum is reduced to 100 ms, and maximum extends to 840 ms. Designers must verify that their target microcontroller's minimum reset hold time requirement is met across the full operating temperature range using these guaranteed values.

Is the LM810M3-4.38/NOPB pin-compatible with other members of the LM809/LM810 family?

Yes - all LM809 and LM810 variants, including LM810M3-4.38/NOPB, share identical SOT-23 (DBZ) 3-pin packaging and pinout (GND, RESET, V_CC). This allows direct substitution between threshold voltages (e.g., 4.38 V, 4.63 V) and output polarities (LM809 = active-low, LM810 = active-high) without PCB changes, provided the system design accommodates the respective reset logic polarity.