Diodes Incorporated ZLDO500T8TA

Overview

ZLDO500T8TA from Diodes Incorporated (formerly Zetex) is an ultra-low-dropout linear regulator delivering a fixed 5.0 V output at up to 300 mA, with dropout as low as 6 mV at 10 mA and 30 mV at 100 mA. It integrates a low-battery flag (open-collector LBF), active-high shutdown control, and thermal shutdown-enabling precise power management in space-constrained, battery-powered systems such as palmtop computers and portable instrumentation.

For engineers reviewing the ZLDO500T8TA datasheet, ZLDO500T8TA pinout, ZLDO500T8TA application, or ZLDO500T8TA equivalent, key selection criteria include dropout voltage vs. load, quiescent current in active/shutdown modes (1 mA / 11 µA), low-battery detection threshold (Vo + 200 mV), and SM8 package compatibility with high-density PCB layouts.

Technical Context

The ZLDO500T8TA employs a precision bandgap reference and error amplifier with external shaping capacitor (10 pF from Pin 8 to Pin 5) to achieve ±2.5% output tolerance and stable regulation across –40°C to +85°C. Its dropout behavior is defined by input–output differential voltage at which output drops 100 mV below nominal Vo.

Low-battery detection uses an internal comparator referenced to Vo + 200 mV (typ), pulling the open-collector LBF pin low when Vin falls within that margin; shutdown control (Pin 2) disables regulation and reduces Iq to 11 µA (typ), with threshold V_TS = 1.5 V (min) for activation.

Key Specifications

Pinout & Package

The ZLDO500T8TA is housed in the Zetex SM8 surface-mount package (8-pin small-outline), measuring 4.9 mm × 6.0 mm × 1.75 mm, optimized for high-density PCB layouts and thermal performance up to 2 W dissipation on a 2-inch² board.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-dropout 5 V regulator applications.

Compared with MCP1700T-5002E/MB and TPS76350DBVR, the ZLDO500T8TA uniquely combines 300 mA capability, sub-30 mV dropout at 100 mA, integrated LBF, and shutdown in a single SM8 package-making it irreplaceable where early battery warning and high-current ultra-LDO performance are co-required.

Availability

ZLDO500T8TA is available at Aetrix Electronics and suitable for portable medical sensors, handheld test equipment, and industrial data loggers requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for ZLDO500T8TA 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 semiconductor company specializing in discrete, analog, and mixed-signal solutions, with broad distribution and manufacturing scale across Asia, Europe, and the Americas.

The ZLDO series was developed by Zetex (acquired by Diodes Inc. in 2008) specifically for ultra-low-power, battery-critical applications demanding minimal dropout, low quiescent current, and intelligent power supervision features.

FAQ

What is the minimum input voltage required to maintain 5.0 V regulation at 300 mA?

The ZLDO500T8TA requires Vin ≥ Vo + 100 mV (typ) at 300 mA load, meaning minimum input is 5.1 V under worst-case conditions. At 25°C and 100 mA, dropout drops to 30 mV, allowing Vin as low as 5.03 V. Input must remain within absolute max of 20 V and never fall below –0.3 V.

Can the Low Battery Flag (LBF) pin drive a microcontroller interrupt directly?

Yes - LBF is an open-collector NPN output rated for 100 µA sink current. It can directly interface to a 3.3 V or 5 V MCU interrupt pin using a 10 kΩ pull-up resistor to the MCU's I/O supply. The flag asserts low when Vin ≤ Vo + 0.4 V (max), providing reliable early warning before regulation collapse.

Is an input capacitor required for stable operation?

An input capacitor is not mandatory per datasheet, but a 1 µF X7R ceramic capacitor placed near Pin 3 (Vin) significantly improves line transient response and reduces noise coupling from shared supply rails. It is strongly recommended for battery-powered or noisy switcher-fed applications.

Why does the datasheet state "NOT RECOMMENDED FOR NEW DESIGNS"?

This notice reflects Diodes Incorporated's product discontinuation policy: the ZLDO500T8TA remains fully functional and supported for existing designs, but newer alternatives like the AP7361 series offer improved PSRR, lower noise, and extended temperature range. Aetrix maintains active inventory and lifetime buy support for legacy ZLDO500T8TA deployments.