Diodes Incorporated ZLDO485T8TA

Overview

ZLDO485T8TA from Diodes Incorporated (formerly Zetex) is an ultra-low-dropout linear regulator delivering a fixed 4.85 V output with 300 mA load capability, 30 mV dropout at 100 mA, and integrated low-battery flag (open-collector NPN) and active-high shutdown control - used in battery-powered instrumentation and portable computing power rails.

For engineers reviewing the ZLDO485T8TA datasheet, ZLDO485T8TA pinout, ZLDO485T8TA application, or ZLDO485T8TA equivalent, key selection criteria include dropout voltage vs. load, quiescent current in active/shutdown modes (1 mA / 11 µA), LBF activation threshold (Vo + 200 mV), and SM8 package thermal performance under 2 W dissipation.

Technical Context

The ZLDO485T8TA employs a precision bandgap reference to maintain ±2.5% output tolerance across –40°C to +85°C, with 100–250 ppm/°C temperature coefficient. Its error amplifier uses an external 10 pF capacitor (pin 8 to pin 5) for stability optimization.

It integrates overtemperature shutdown (trip at ~125°C), open-collector low-battery flag triggered when Vin falls within 200 mV of Vo, and high-impedance shutdown input requiring <10 µA drive current and switching at 1.5 V (high = disable). Output noise is 190 µV RMS (10 Hz–100 kHz).

Key Specifications

Pinout & Package

Package: SM8 (8-pin small-outline surface-mount, 5.0 mm × 6.2 mm, 1.75 mm height), thermally enhanced for up to 2 W dissipation on 2″×2″ PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1703T-485I/MB and NCP1117DT485T5G, the ZLDO485T8TA uniquely combines sub-100 mV dropout, integrated LBF, and shutdown control in an SM8 package - making it irreplaceable for space-constrained, battery-aware embedded systems requiring predictive power management.

Availability

ZLDO485T8TA is available at Aetrix Electronics and suitable for battery-powered devices, portable instruments, and laptop/palmtop computers requiring stable component supply with long-term lifecycle visibility.

Supply support for ZLDO485T8TA 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 for power management, signal integrity, and connectivity.

The ZLDO series was designed specifically for ultra-low-power, battery-critical applications - emphasizing minimal dropout, low quiescent current, and integrated system-monitoring functions like LBF and shutdown.

FAQ

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

The ZLDO485T8TA requires Vin ≥ Vo + 100 mV to sustain regulation at 300 mA, i.e., minimum 4.95 V. This is confirmed by the 100 mV dropout specification at full load. Below this differential, output voltage declines linearly with input - not abruptly - allowing graceful degradation rather than hard failure.

Can the Low Battery Flag (LBF) be used to drive a microcontroller interrupt directly?

Yes - the LBF pin is an open-collector NPN output rated for 100 µA sink current. It pulls low at ≤0.4 V when Vin ≤ Vo + 400 mV (guaranteed), and remains high-impedance otherwise. A 10 kΩ pull-up to 3.3 V or 5 V provides compatible logic levels for most MCU interrupts without level-shifting.

Is the 10 pF capacitor on the Spg pin mandatory for stability?

Yes - the 10 pF capacitor from Spg (pin 8) to Vout (pin 5) is required for guaranteed stability across all load conditions and temperatures. Reducing it improves transient response but risks oscillation above 100 mA load; omitting it causes sustained ringing and potential output collapse under dynamic loads.

Why does the datasheet state "not recommended for new designs"?

This notice reflects Diodes Incorporated's product lifecycle policy: the ZLDO485T8TA remains fully available and supported, but newer alternatives (e.g., AP7361D, AP2204) offer improved PSRR, lower noise, and extended temperature range. Customers starting new designs should evaluate those parts - though ZLDO485T8TA remains valid for legacy refresh or cost-sensitive replacements.