Diodes Incorporated ZXLD1356QET5TA

Overview

ZXLD1356QET5TA from Diodes Incorporated is an automotive-grade continuous-mode inductive step-down LED driver IC designed for single or series-connected LED strings in high-reliability lighting systems. It operates from 6V to 60V input, delivers up to 550mA output current with ±0.8% accuracy, supports PWM dimming up to 1000:1, and integrates open-circuit LED protection. It is used in rear fog lamps, position lights, and internal door lighting where AEC-Q100 Grade 1 compliance (−40°C to +125°C) is required.

For engineers reviewing the ZXLD1356QET5TA datasheet, ZXLD1356QET5TA pinout, ZXLD1356QET5TA application, or ZXLD1356QET5TA equivalent, key selection criteria include its adjustable current sense threshold (200mV), TSOT25 thermal package with exposed pad, 360kHz typical switching frequency, and dual-mode ADJ pin control (DC voltage or PWM) for precise brightness regulation in automotive lighting subsystems.

Technical Context

The ZXLD1356QET5TA implements a self-oscillating buck topology using internal NDMOS switch (LX pin), current-sense comparator with 15% hysteresis, and integrated 1.25V reference. Its operation relies on external RS resistor to set nominal LED current via VSENSE = 200mV (VIN-referenced), and ADJ pin voltage directly scales the current sense threshold proportionally.

Switching frequency varies with VIN, LED count, and inductor value (e.g., 360kHz at VIN = 24V, L = 68µH, 3 LEDs), while duty cycle remains within 1–99% across operating conditions. Thermal performance is managed via TSOT25's exposed pad (θJA = 44°C/W), and shutdown is triggered when ADJ voltage falls below 0.20V.

Key Specifications

Pinout & Package

TSOT25 (V-DFN3030-6) package with thermally enhanced exposed pad (EP); EP must be connected to power ground for thermal management but not used as primary GND current return path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver applications.

Compared with AL8862Q-13 and LM3409QMY/NOPB, the ZXLD1356QET5TA uniquely combines integrated switch, 1000:1 PWM dimming, and AEC-Q100 Grade 1 qualification in a thermally optimized 3mm×3mm package-making it optimal for space-constrained, dimmable automotive LED modules requiring zero-fault tolerance.

Availability

ZXLD1356QET5TA is available at Aetrix Electronics and suitable for automotive rear fog lamps, position lights, and interior door lighting requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZXLD1356QET5TA 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 ICs, specializing in high-reliability power management, signal integrity, and lighting solutions for automotive and industrial markets.

The ZXLD1356QET5TA belongs to Diodes' automotive LED driver product line, engineered specifically for AEC-Q100-compliant constant-current regulation in safety-critical exterior and interior lighting applications.

FAQ

What is the minimum sense resistor value for 550mA output?

The minimum RS value is 0.36Ω when the ADJ pin is floating (VADJ = 1.25V), yielding IOUTnom = 0.2V / 0.36Ω ≈ 555mA. Using lower values risks exceeding the 0.55A continuous LX current rating and may trigger thermal shutdown. Derating is required below VIN = 16V due to increased RDS(on).

How does the ADJ pin function in PWM dimming mode?

The ADJ pin accepts a PWM signal (frequency <300Hz recommended) to modulate LED current between 0.1% and 100% of nominal. Internal low-pass filtering converts PWM duty cycle into an effective DC voltage that scales the 200mV VSENSE threshold linearly. No external RC filter is needed-the device integrates the necessary time constant.

Can ZXLD1356QET5TA drive more than one LED string?

No-it is designed for single-series LED strings only. Driving parallel strings would cause current imbalance due to forward-voltage mismatches. For multi-string applications, separate ZXLD1356QET5TA channels or a multi-channel driver like the AL8863Q must be used to ensure per-string current regulation and fault isolation.

Is the exposed pad electrically connected internally?

Yes-the exposed pad (EP) is internally connected to the die substrate and must be soldered to a solid power ground plane. It serves as the primary thermal conduction path (θJC = 14°C/W) but is not electrically tied to any signal pin. It must never be connected to voltage potentials other than 0V.