Texas Instruments LM809M3X-2.93

Overview

LM809M3X-2.93 from Texas Instruments is a 3-pin SOT-23 microprocessor reset supervisor IC with a factory-programmed 2.93 V ±3% precision reset threshold, 240 ms typical active-low reset pulse width, and 15 µA typical supply current. It monitors VCC in 3.3 V and 3 V systems, asserting RESET during power-up, brown-out, and power-down-used in programmable logic controllers and industrial automation equipment.

For engineers reviewing the LM809M3X-2.93 datasheet, LM809M3X-2.93 pinout, LM809M3X-2.93 application, or LM809M3X-2.93 equivalent, key selection criteria include guaranteed reset validity down to VCC ≥1 V, immunity to VCC transients ≤20 µs at 100 mV underthreshold, and compatibility with bidirectional µP reset pins via 4.7 kΩ series resistor.

Technical Context

The LM809M3X-2.93 implements a precision bandgap-based voltage comparator with internal hysteresis and a fixed 240 ms reset timeout timer. Its active-low RESET output remains asserted while VCC < 2.93 V and for 240 ms after VCC rises above threshold, ensuring reliable microprocessor initialization across –40°C to +105°C.

It features transient immunity (20 µs max glitch rejection at 100 mV underthreshold), low quiescent current (15 µA typ at 25°C), and guaranteed operation down to VCC = 1 V-enabling use in battery-backed and low-voltage embedded systems where supply stability is marginal during startup or brown-out.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD3+T and TPS3808G33DBVR, LM809M3X-2.93 delivers fixed-precision 2.93 V supervision with industry-standard 240 ms timeout and proven industrial temperature reliability-requiring zero external components and minimal PCB footprint.

Availability

LM809M3X-2.93 is available at Aetrix Electronics and suitable for industrial automation, renewable energy inverters, and factory HMI systems requiring stable component supply with long-term lifecycle assurance.

Supply support for LM809M3X-2.93 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 specializing in analog and embedded processing technologies, with leadership in power management, signal chain, and high-reliability industrial ICs.

The LM809 product line delivers precision voltage supervisors for microprocessor reset applications, designed specifically for robust operation in harsh industrial and automotive environments with minimal external components.

FAQ

What is the exact reset threshold voltage of LM809M3X-2.93 and how does it vary with temperature?

The LM809M3X-2.93 has a factory-programmed reset threshold of 2.93 V with ±3% tolerance at 25°C. Over the full –40°C to +105°C operating range, the threshold drifts no more than ±30 ppm/°C, resulting in a worst-case variation of approximately ±0.088 V (2.842 V to 3.018 V). This tight specification ensures reliable reset behavior across industrial temperature extremes without external trimming.

Does LM809M3X-2.93 require an external pull-up resistor on the RESET pin?

Yes, LM809M3X-2.93 features an open-drain active-low RESET output and requires an external pull-up resistor to VCC or the target microprocessor's I/O rail. A typical value is 10 kΩ to 100 kΩ; TI recommends 4.7 kΩ when interfacing with bidirectional µP reset pins (e.g., Motorola 68HC11) to ensure proper voltage translation and avoid contention.

Can LM809M3X-2.93 operate reliably when VCC drops below 1 V?

No-LM809M3X-2.93 guarantees valid RESET output only for VCC ≥1 V. Below 1 V, the internal circuitry cannot maintain defined logic states, and the RESET pin enters high-impedance. For applications requiring reset assertion down to 0 V, TI recommends adding a 100 kΩ pull-down resistor from RESET to GND to prevent floating logic levels during deep brown-out.

What is the maximum VCC transient duration LM809M3X-2.93 can reject without asserting reset?

LM809M3X-2.93 rejects VCC transients up to 20 µs in duration when the dip magnitude is ≤100 mV below the 2.93 V threshold. This immunity is verified across temperature and ensures robust operation in electrically noisy environments such as motor drives or switch-mode power supply proximity-without requiring additional filtering beyond the recommended 0.1 µF bypass capacitor.

Is LM809M3X-2.93 pin-compatible with other members of the LM809 family?

Yes-LM809M3X-2.93 shares identical SOT-23 (DBZ) 3-pin package, pinout (GND–RESET–VCC), and footprint with all LM809 variants (e.g., LM809M3X-2.63, LM809M3X-3.08). This allows direct substitution within the same family for different threshold requirements without PCB layout changes, provided system timing and voltage margin constraints are re-validated.