Diodes Incorporated ZLDO1117QK50TC

Overview

ZLDO1117QK50TC from Diodes Incorporated is an automotive-grade, fixed-output 5.0V low-dropout linear regulator delivering up to 1A output current with ±2% output voltage tolerance over -40°C to +105°C ambient, 1.2V maximum dropout at full load, and qualified to AEC-Q100 Grade 2 for use in engine control units and ADAS power rails.

For engineers reviewing the ZLDO1117QK50TC datasheet, ZLDO1117QK50TC pinout, ZLDO1117QK50TC application, or ZLDO1117QK50TC equivalent, key selection criteria include dropout voltage under 1.2V at 1A, MLCC-compatible stability with ≥4.7µF ceramic output capacitance, thermal shutdown behavior, and compliance with automotive PPAP and IATF16949 manufacturing requirements.

Technical Context

The ZLDO1117QK50TC implements a bandgap-referenced error amplifier driving a PNP pass transistor, enabling stable regulation with minimal headroom. Its internal 1.25V reference and precision resistor divider yield 5.0V ±2% output across line, load, and temperature variations.

It features built-in current limiting (≥1.1A), thermal shutdown activation at ~150°C junction temperature, and fast transient response optimized for MLCC output capacitors (ESR ≤ 0.5Ω). Ripple rejection reaches 80dB at 120Hz with 25µF tantalum output capacitance.

Key Specifications

Pinout & Package

Package: TO252 (DPAK), surface-mount, thermally enhanced with exposed tab connected to VOUT for PCB heat spreading.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output 5V automotive LDO applications.

Compared with TLV1117-50QDCKR and NCP1117ST50T3G, the ZLDO1117QK50TC uniquely combines AEC-Q100 Grade 2 qualification, TO252 thermal performance (73°C/W), and guaranteed 1.2V dropout at 1A-making it the only option validated for sustained 1A loads at +105°C ambient in safety-critical automotive domains.

Availability

ZLDO1117QK50TC is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, infotainment USB hubs, and body control modules requiring stable component supply across automotive production lifecycles.

Supply support for ZLDO1117QK50TC 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 manufacturer specializing in discrete, analog, and mixed-signal devices for automotive, industrial, and consumer markets, with ISO/TS 16949 (now IATF16949) certified wafer fabs and assembly sites.

The ZLDO1117Q series belongs to Diodes' automotive-qualified linear regulator product line, engineered specifically for high-reliability power management in AEC-Q100-compliant systems operating across extended temperature ranges and harsh electrical environments.

FAQ

What is the minimum input voltage required for ZLDO1117QK50TC to regulate at full 1A load?

The device requires VIN ≥ 6.2V to maintain regulation at 1A load, based on its 1.2V maximum dropout voltage specification. At lower input voltages, it enters dropout mode with unregulated output. For reliable operation across temperature and tolerance, design with VIN ≥ 6.4V minimum per the recommended operating condition table.

Can ZLDO1117QK50TC be used with 2.2µF ceramic output capacitors?

No. The datasheet mandates a minimum 4.7µF output capacitor with ESR between 0.05Ω and 0.5Ω for stability. Using 2.2µF violates the minimum capacitance requirement and risks oscillation or poor transient response. Valid alternatives include 4.7µF X7R MLCC, 4.7µF tantalum, or 47µF aluminum electrolytic.

Does ZLDO1117QK50TC require an input capacitor?

An input capacitor is not strictly required for stability but is strongly recommended when the regulator is located >2 inches from the main power filter. A 1µF ceramic capacitor placed close to the VIN pin reduces high-frequency noise and prevents input voltage sag during load transients, especially critical in automotive environments with long harness runs.

How does thermal shutdown behave during sustained overload?

When junction temperature reaches ~150°C, the internal thermal limiter disables the pass transistor, dropping VOUT to near zero. After die cooling by ~10–20°C, the device automatically recovers and resumes regulation. This hiccup-mode behavior protects against permanent damage but causes intermittent output-designers must ensure heatsinking or current limiting prevents repeated cycling in continuous operation.