Diodes Incorporated ZLDO330T8TC

Overview

ZLDO330T8TC from Zetex Semiconductors is an ultra-low-dropout linear regulator delivering a fixed 3.3 V output with 300 mA load capability, 30 mV dropout at 100 mA, 560 µA typical quiescent current, and integrated low-battery flag (open-collector LBF) and active-high shutdown control - used in portable instrumentation power rails where input-to-output margin is constrained to ≤300 mV.

For engineers reviewing the ZLDO330T8TC datasheet, ZLDO330T8TC pinout, ZLDO330T8TC application, or ZLDO330T8TC equivalent, key selection criteria include dropout voltage vs. load, shutdown quiescent current (11 µA), LBF threshold accuracy (V_IN = V_OUT + 0.2–0.4 V), thermal shutdown activation at 125°C, and SM8 package layout compatibility.

Technical Context

The ZLDO330T8TC 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 at 100 mV output deviation from nominal, with measured values of 6 mV (10 mA), 30 mV (100 mA), and 100 mV (300 mA).

It integrates three functional blocks: a low-battery comparator monitoring input-to-output differential (trip at V_IN ≤ V_OUT + 0.4 V), thermal shutdown circuitry activating at 125°C junction temperature, and high-impedance shutdown control (I_IN < 10 µA, V_TH = 1.5 V) that reduces I_Q to 11 µA typical when asserted.

Key Specifications

Pinout & Package

The ZLDO330T8TC is housed in the Zetex SM8 surface-mount package (8-pin small-outline), measuring 4.9 mm × 6.0 mm × 1.75 mm, with gull-wing leads and exposed thermal pad (not electrically connected). Pin 1 is marked by a beveled corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-3302E/TT and TPS76333DBVR, the ZLDO330T8TC uniquely combines 300 mA capability, sub-30 mV dropout at 100 mA, integrated LBF, and thermal shutdown in a single SM8 package - making it irreplaceable for battery-critical systems requiring both performance headroom and fault awareness.

Availability

ZLDO330T8TC is available at Aetrix Electronics and suitable for portable medical sensors, industrial handheld terminals, and smart meter backup power systems requiring stable component supply with long-term lifecycle visibility.

Supply support for ZLDO330T8TC 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 (now part of Diodes Incorporated) specialized in high-performance analog and power management ICs for space-constrained, battery-sensitive applications.

The ZLDO series was engineered specifically for ultra-low-dropout regulation in portable electronics, emphasizing minimal input margin, integrated fault signaling, and thermal resilience without external protection components.

FAQ

What is the minimum input voltage required for regulation at full 300 mA load?

The ZLDO330T8TC maintains regulation as long as the input voltage exceeds the output voltage by at least 100 mV (typical dropout at 300 mA). Therefore, with a nominal 3.3 V output, Vin must be ≥3.4 V under full load. The absolute minimum specified input is –0.3 V, but regulation only occurs above V_OUT + V_DROP.

Can the low-battery flag (LBF) drive a microcontroller interrupt directly?

Yes - the LBF is an open-collector NPN output rated for 100 µA sink current. It pulls low when V_IN drops to V_OUT + 0.4 V (max). A 10 kΩ pull-up to 3.3 V yields ~0.33 V high-level noise margin and is compatible with standard CMOS inputs; no level-shifter needed.

Is the SM8 package thermally enhanced, and what is its θ_JA?

The SM8 package has no exposed thermal pad; its thermal resistance is 65°C/W (θ_JA) when mounted on a 2-inch square PCB per datasheet Note 1. For continuous 300 mA operation at 20 V input, power dissipation reaches ~5 W - exceeding the 2 W absolute maximum rating - so derating or heatsinking is mandatory in high-V_IN/high-I_LOAD use cases.

Why does Pin 6 (D/C) require "Do Not Connect" handling?

Pin 6 connects internally to a high-impedance node in the error amplifier's compensation network. External connection introduces parasitic capacitance and gain perturbation, causing oscillation or degraded transient response. Datasheet Figure 4-65 confirms instability when Pin 6 is loaded - hence strict "do not connect" directive applies.