Diodes Incorporated ZSM530GTA

Overview

ZSM530GTA from Zetex Semiconductors (now Diodes Incorporated) is a three-terminal under-voltage monitor IC for microprocessor power-on reset and brown-out detection in 5 V systems. It features a fixed 4.3 V threshold, 20 mV hysteresis, open-collector output capable of sinking ≥10 mA, guaranteed operation from 1.0 V to 6.5 V supply, and internal clamp diode for delay capacitor discharge.

For engineers reviewing the ZSM530GTA datasheet, ZSM530GTA pinout, ZSM530GTA application, or ZSM530GTA equivalent, key selection criteria include precise 4.3 V trip point, low quiescent current (175–260 µA at 5 V), temperature-stable threshold (±0.05 V over −40°C to +85°C), and SOT223 package compatibility with high-current sink capability and thermal performance up to 2 W.

Technical Context

The ZSM530GTA integrates a precision bandgap voltage reference and comparator with built-in hysteresis to eliminate oscillation during supply voltage transitions near the 4.3 V threshold. Its open-collector output stage supports direct interface to TTL/CMOS logic via a single pull-up resistor.

Operation begins at V_CC ≥ 1.0 V; below threshold, output remains low to assert reset; above threshold, output floats high. The internal clamp diode enables controlled discharge of external timing capacitors used for programmable reset delay, supporting deterministic power-on sequencing in embedded controllers.

Key Specifications

Pinout & Package

Package: SOT223 (4-pin, pin 4 floating or connected to pin 2 per datasheet). Thermal pad on underside enhances heat dissipation; rated P_D = 2 W with 2-inch² PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809T and TLV809K, the ZSM530GTA uniquely combines 4.3 V precision threshold, integrated clamp diode for RC timing, and 10 mA sink drive in SOT223-making it optimal for industrial and automotive 5 V systems requiring robust, self-contained reset generation without layout compromises.

Availability

ZSM530GTA is available at Aetrix Electronics and suitable for microprocessor power-on reset, battery-powered instrumentation, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZSM530GTA 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 was a UK-based analog and power management IC designer, acquired by Diodes Incorporated in 2008; known for high-reliability supervisory and protection devices.

The ZSM530 series belongs to Zetex's voltage supervisor product line, engineered specifically for deterministic power-on reset and brown-out detection in 5 V microprocessor systems with minimal external components.

FAQ

What is the function of Pin 4 on the ZSM530GTA SOT223 package?

Pin 4 is internally unconnected (NC) but serves as a thermal pad. Per the datasheet, it may be left floating or tied to Pin 2 (GND) to improve thermal conduction to the PCB ground plane. It is not electrically functional but critical for achieving the rated 2 W power dissipation in SOT223.

Can the ZSM530GTA be used with a 3.3 V microcontroller supply?

No-the ZSM530GTA has a fixed 4.3 V threshold optimized for 5 V systems. Using it on a 3.3 V rail would cause continuous reset assertion since V_CC never reaches the trip point. For 3.3 V systems, consider the ZSM330 (3.08 V threshold) or alternate supervisors like TPS3809L33.

How is reset delay time calculated when using an external capacitor?

Reset delay is set by an RC network between V_CC and OUT, with the internal clamp diode discharging the capacitor. Delay time T_DY = R × C × ln[1/(1 − V_TH(MPU)/V_IN)], where V_TH(MPU) is the target microcontroller's reset threshold voltage and V_IN is the monitored supply.

Does the ZSM530GTA require an external pull-up resistor on its output?

Yes-an external pull-up resistor is mandatory. The open-collector output cannot drive high; typical values range from 4.7 kΩ to 10 kΩ to +5 V or +3.3 V, depending on load capacitance and required rise time. Without it, the output remains undefined during normal operation.