Diodes Incorporated ZM331643C

Overview

ZM331643C from Zetex Semiconductors is a 3-terminal under-voltage monitor IC for microprocessor power-on reset and brown-out detection, featuring a fixed 2.68 V threshold, 60 mV hysteresis, open-collector output sinking ≥10 mA, and guaranteed operation from 1.0 V to 10 V supply. It delivers precise reset generation in 3 V logic systems with internal voltage reference and built-in clamp diode.

For engineers reviewing the ZM331643C datasheet, ZM331643C pinout, ZM331643C application, or ZM331643C equivalent, key selection factors include threshold accuracy over temperature (±0.06 V), sink current capability at low Vcc (2.0 mA @ 1.0 V), propagation delay (2.5 µs), quiescent current (125–190 µA), and TO-92 package compatibility with legacy through-hole designs.

Technical Context

The ZM331643C integrates a precision bandgap voltage reference and comparator with internal hysteresis to eliminate oscillation during supply ramp-up/down transitions. Its open-collector output interfaces directly to TTL/CMOS inputs via a single pull-up resistor.

Operation begins at 1.0 V supply, holding output low until Vcc exceeds 2.68 V (rising edge); on falling Vcc, output reasserts low below 2.62 V (2.68 V − 60 mV hysteresis), enabling reliable power-on and brown-out reset signaling without external timing components.

Key Specifications

Pinout & Package

Supplied in TO-92 package (suffix C), with leads configured as Collector (pin 1), Emitter (pin 2), and Base (pin 3) - functionally mapped to V_IN, GND, and open-collector output respectively per Zetex connection diagram.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar under-voltage monitor applications.

Compared with MAX809TRD2T and TLV803EB26DPWR, the ZM331643C uniquely combines TO-92 compatibility, integrated clamp diode for RC delay, and 60 mV hysteresis-making it optimal for cost-sensitive, through-hole, and timing-flexible 3 V reset designs.

Availability

ZM331643C is available at Aetrix Electronics and suitable for microprocessor systems, battery-powered instrumentation, automotive body control modules, and industrial PLC I/O cards requiring stable component supply and long-term obsolescence management.

Supply support for ZM331643C 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

Zetex Semiconductors plc was a UK-based analog and discrete semiconductor manufacturer specializing in high-performance, application-optimized devices for industrial and automotive markets before its acquisition by Diodes Incorporated in 2008.

The ZM33164 series belongs to Zetex's supervisory IC product line, designed specifically for robust, low-cost power monitoring in resource-constrained embedded systems with emphasis on thermal stability and ease of integration.

FAQ

What is the minimum supply voltage required for ZM331643C to assert a valid reset signal?

The ZM331643C begins operation at 1.0 V supply and holds its open-collector output low until V_IN rises above 2.68 V. Below 1.0 V, output behavior is undefined per absolute maximum ratings; however, functional reset assertion is guaranteed from 1.0 V upward, making it suitable for deep battery discharge detection.

Can ZM331643C drive a 10 kΩ pull-up resistor directly to 5 V logic?

Yes. With 10 mA sink capability and 1.0 V saturation voltage at 8 mA load, the output pulls down to ≤1.0 V when driving a 10 kΩ pull-up to 5 V - delivering >4 V logic swing compatible with standard TTL and 5 V CMOS inputs without level-shifting.

How does the internal clamp diode function in reset timing circuits?

The internal clamp diode connects between the output pin and ground. When used with an external RC network (capacitor to output, resistor to V_IN), it discharges the capacitor rapidly upon reset release, enabling precise, repeatable reset pulse width control without adding a discrete diode.

Is ZM331643C pin-compatible with other Zetex reset monitors like ZM331643G?

No. While ZM331643C (TO-92) and ZM331643G (SOT-223) share identical electrical specifications and functional pin mapping (V_IN/GND/OUT), their physical pinouts differ: TO-92 uses collector-emitter-base layout, whereas SOT-223 assigns pin 4 as thermal pad (floating or tied to emitter). PCB layout is not interchangeable.