Diodes Incorporated ZLDO1117K25TC

Overview

ZLDO1117K25TC from Diodes Incorporated is a fixed-output 2.5V, 1A low dropout linear regulator in TO252 package, featuring 1.2V max dropout at full load, ±2% output voltage tolerance over industrial temperature range (−40°C to +125°C), and compatibility with MLCC output capacitors. It delivers stable power for 2.5V logic rails and I/O interfaces in automotive and industrial control systems.

For engineers reviewing the ZLDO1117K25TC datasheet, ZLDO1117K25TC pinout, ZLDO1117K25TC application, or ZLDO1117K25TC equivalent, key selection criteria include dropout voltage at 1A, thermal resistance (θ_JA = 73°C/W), AEC-Q100 Grade 2 qualification, MLCC stability support, and fixed 2.5V output accuracy under line/load/temperature variation.

Technical Context

The ZLDO1117K25TC employs an internal 1.25V bandgap reference and error amplifier to regulate output with fast transient response and built-in current limiting. Its quasi-LDO architecture achieves 1.2V dropout at 1A while maintaining 60–80dB ripple rejection at 120Hz.

Thermal shutdown activates at ~150°C junction temperature, and the device operates across −40°C to +125°C with guaranteed performance up to 125°C junction. Output stability requires ≥4.7µF MLCC (ESR ≤ 0.5Ω) and supports disable functionality via external transistor circuitry per Figure 4.

Key Specifications

Pinout & Package

Package: TO252-3L (DPAK), surface-mount, thermally enhanced with exposed tab connected to VOUT. Thermal resistance θ_JA = 73°C/W (tested on 2″×2″ polyimide PCB, 1 oz copper, 2cm×2cm pad).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-2502E/MB and TLV1117-25CDCYR, ZLDO1117K25TC uniquely combines 1A current, AEC-Q100 Grade 2, TO252 thermal performance (73°C/W), and guaranteed MLCC stability - making it the only choice for automotive 2.5V I/O rails requiring robustness and layout flexibility.

Availability

ZLDO1117K25TC is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O modules, medical imaging sensor biasing, and test equipment reference rails requiring stable component supply, long lifecycle continuity, and AEC-Q100 compliance.

Supply support for ZLDO1117K25TC 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 manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for automotive, industrial, and computing markets.

The ZLDO1117 product line delivers enhanced-performance LDO regulators targeting automotive-grade power rails and industrial systems demanding extended temperature operation, low dropout, and MLCC compatibility - directly addressing design needs for next-generation 2.5V/3.3V logic and interface supplies.

FAQ

What is the minimum input voltage required for ZLDO1117K25TC to maintain regulation?

The minimum input voltage is 3.9V - derived from the 2.5V output plus 1.4V headroom specified in the Recommended Operating Conditions table. Below this, the device enters dropout mode where output voltage drops linearly with input. At 1A load, dropout voltage is guaranteed ≤1.2V, so 3.7V input still yields functional regulation, though line regulation degrades.

Can ZLDO1117K25TC be used with ceramic capacitors smaller than 4.7µF?

No - the datasheet explicitly mandates ≥4.7µF MLCC (X7R dielectric) with ESR between 0.05Ω and 0.5Ω for stability. Using smaller values risks oscillation or poor transient response. The 4.7µF minimum is validated across temperature and load; reducing capacitance violates the compensation design and may cause instability under dynamic load conditions.

Does ZLDO1117K25TC support enable/disable functionality?

It does not have a dedicated EN pin, but Figure 4 in the datasheet shows a proven external disable circuit using an NPN transistor (MMBT3904) tied to the adjust pin (pin 1). When the transistor pulls pin 1 low, regulation ceases and VOUT drops. This method preserves all protection features and is suitable for power sequencing in multi-rail systems.

How does thermal performance differ between TO252 and SOT223 packages for this part?

TO252 (ZLDO1117K25TC) has θ_JA = 73°C/W vs. SOT223's 107°C/W under identical test conditions - a 32% improvement. This allows 1A operation at up to 15°C higher ambient temperature before reaching 125°C junction limit. The TO252's larger copper tab also provides superior heat spreading on PCBs with limited thermal vias or copper area.