Diodes Incorporated ZLDO1117QKTC

Overview

ZLDO1117QKTC from Diodes Incorporated is an automotive-grade, adjustable-output low-dropout linear regulator delivering 1A output current with ≤1.2V dropout at full load, ±2% output voltage tolerance over -40°C to +105°C, and AEC-Q100 Grade 2 qualification. It supports input voltages up to 18V and stable 1.2V–5.0V outputs using MLCC or tantalum capacitors, targeting power rails for automotive infotainment SoCs and ADAS sensor interfaces.

For engineers reviewing the ZLDO1117QKTC datasheet, ZLDO1117QKTC pinout, ZLDO1117QKTC application, or ZLDO1117QKTC equivalent, key selection criteria include dropout voltage under 1.2V at 1A, thermal shutdown behavior, MLCC-compatible stability, and AEC-Q100-compliant manufacturing traceability in TO252 (DPAK) packaging.

Technical Context

The ZLDO1117QKTC implements a quasi-LDO architecture with a precision 1.25V internal reference and feedback-controlled pass transistor. Its regulation loop maintains output accuracy across line (2.7V–18V VIN), load (10mA–1A), and temperature (-40°C to +105°C ambient) variations while sustaining <0.2% load regulation and >60dB ripple rejection at 120Hz.

Thermal protection activates at +150°C junction temperature, forcing cyclic shutdown/restart; thermal resistance is θJA = 73°C/W (TO252 on 1oz copper, 2cm×2cm pad). The device requires ≥4.7µF output capacitance with ESR ≤0.5Ω and supports both fixed- and adjustable-output configurations via external resistor dividers on the ADJ/GND pin.

Key Specifications

Pinout & Package

Package: TO252 (DPAK), surface-mount, thermally enhanced with exposed tab connected to VOUT for PCB heat spreading. Pin 1 (ADJ/GND) sets output voltage via resistor divider in adjustable mode or serves as ground in fixed variants; Pin 2 (VOUT) delivers regulated output; Pin 3 (VIN) accepts input up to 18V; Tab is electrically tied to VOUT.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1117ST50T3G and TLV1117-33CDCYR, the ZLDO1117QKTC uniquely combines AEC-Q100 Grade 2 qualification, 1A continuous current at +105°C ambient, and MLCC compatibility - making it the only option validated for safety-critical automotive power domains requiring traceable lifecycle management.

Availability

ZLDO1117QKTC is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, and body control units requiring stable component supply with full AEC-Q100 documentation and PPAP readiness.

Supply support for ZLDO1117QKTC 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, with design centers in Asia, Europe, and the U.S., and wafer fabrication in Taiwan and China.

The ZLDO1117Q series belongs to Diodes' automotive-qualified linear regulator product line, engineered specifically for robust, low-noise power delivery in harsh-temperature vehicle environments - emphasizing AEC-Q100 compliance, thermal resilience, and MLCC compatibility.

FAQ

What is the minimum input voltage required for regulation at 3.3V output?

The ZLDO1117QKTC requires VIN ≥ VOUT + 1.3V for proper regulation, so minimum input is 4.6V at 3.3V output. Below this threshold, the device enters dropout mode with reduced PSRR and increased output impedance - verified by SOA curve and dropout vs. temperature plots in DS37075 Rev. 3-2.

Can the ZLDO1117QKTC be used with 10µF X5R MLCCs instead of tantalum?

Yes - the ZLDO1117QKTC is explicitly characterized for stability with ≥4.7µF X7R/X5R MLCCs having ESR between 0.05Ω and 0.5Ω. X5R dielectrics are acceptable if rated for ≥105°C and meet ESR specs; avoid Y5V due to capacitance drift.

Does the ADJ pin require a bypass capacitor for standard 3.3V fixed operation?

No - the ADJ pin is internally connected to ground in fixed-output variants like ZLDO1117QK33TC, but the ZLDO1117QKTC is the adjustable version. For ZLDO1117QKTC configured as 3.3V, a bypass capacitor on ADJ improves ripple rejection; 10µF is typical at 120Hz per Figure 1 and ripple rejection curves on page 6.

How does thermal shutdown behave during sustained overload?

When junction temperature reaches +150°C, the ZLDO1117QKTC disables output and remains off until die cools to ~135°C, then re-enables - creating a thermal cycling pattern. This behavior is confirmed in Recommended Operating Conditions (Note 6) and protects against permanent failure during board-level thermal runaway scenarios.