Diodes Incorporated ZSM300CL

Overview

ZSM300 from Diodes Incorporated is an obsolete three-terminal under-voltage monitor IC with 3.0V threshold, 2.5% accuracy, 140ms reset timeout, open-drain output, and operating supply range of 1.2V to 6.0V. It functions as a system supervisory device for microcontroller reset assertion during brownout conditions in embedded power management circuits.

For engineers reviewing the ZSM300 datasheet, ZSM300 pinout, ZSM300 application, or ZSM300 equivalent, key selection considerations include reset threshold tolerance, timeout duration, output drive type, supply voltage compatibility, and direct replacement availability due to its discontinued status.

Technical Context

The ZSM300 implements a precision bandgap reference and comparator-based monitoring architecture to detect supply voltage drops below its fixed 3.0V threshold. Its internal timing circuit generates a guaranteed 140ms active-low reset pulse upon undervoltage detection.

It features an open-drain output stage compatible with 3.3V and 5V logic systems, requiring an external pull-up resistor. The device draws only 1.1μA quiescent current and operates across industrial temperature range (–40°C to +85°C) without external components.

Key Specifications

Pinout & Package

Supplied in SOT-23-3 package with standard pinout: Pin 1 = V_CC, Pin 2 = GND, Pin 3 = RESET (open-drain output).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZSM300, APX803L-30 offers identical functionality and pin compatibility for seamless migration, while APX803S-30 trades open-drain flexibility for reduced component count-both support full industrial temperature range and require no layout changes beyond output termination.

Availability

ZSM300 is available at Aetrix Electronics and suitable for microcontroller reset supervision, industrial sensor node power monitoring, and smart meter backup switchover requiring stable component supply despite its obsolete status.

Supply support for ZSM300 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions.

The ZSM300 belongs to Diodes' legacy supervisor IC product line, designed specifically for cost-sensitive, space-constrained embedded systems requiring simple, single-threshold voltage monitoring with guaranteed reset timing.

FAQ

Is ZSM300 still in production?

No. Diodes Incorporated officially discontinued the ZSM300 and marked it obsolete in July 2021. It is no longer manufactured, though limited legacy stock may be available through authorized channels. Customers are directed to migrate to APX803L or APX803S series for new designs.

What is the function of the open-drain RESET output?

The open-drain RESET output sinks current when active (low), allowing multiple monitors to share a common reset bus via wired-OR connection. An external pull-up resistor sets the logic-high level and determines rise time; typical values range from 10kΩ to 100kΩ depending on capacitive load and speed requirements.

Can ZSM300 monitor voltages below 1.2V?

No. The ZSM300 requires a minimum V_CC of 1.2V to operate its internal bandgap reference and comparator. Monitoring sub-1.2V rails (e.g., 0.9V core supplies) is not supported and will result in undefined reset behavior or no output assertion.

How does the 140ms reset timeout behave during supply recovery?

Upon V_CC rising above the 3.0V threshold, the ZSM300 holds RESET low for a minimum of 140ms before releasing it high. This timeout is internally generated and independent of supply slew rate, ensuring deterministic reset hold time regardless of how quickly the rail recovers.