Diodes Incorporated ZXLD1350QET5TA

Overview

ZXLD1350QET5TA from Diodes Incorporated is an AEC-Q100 Grade 2 qualified automotive buck LED driver IC with integrated 30V NDMOS switch, 7–30V input range, and externally adjustable output current up to 350mA via ADJ pin voltage or PWM control. It operates in hysteretic mode, delivers up to 95% efficiency, and supports 100:1 dimming range using low-frequency PWM for headlight and interior lighting systems.

For engineers reviewing the ZXLD1350QET5TA datasheet, ZXLD1350QET5TA pinout, ZXLD1350QET5TA application, or ZXLD1350QET5TA equivalent, key selection criteria include its TSOT25 package thermal performance, ±15% current sense hysteresis, 1.25V internal reference accuracy (±4%), 0.2V shutdown threshold, and 40V transient capability for automotive 12V/24V rail environments.

Technical Context

The ZXLD1350QET5TA implements a self-oscillating hysteretic buck topology with high-side current sensing via the ISENSE pin and internal comparator referencing VREF (1.25V). Its switching frequency varies dynamically with load and input voltage, typically 250kHz at 12V/350mA, and features built-in 15% hysteresis on the 100mV current-sense threshold to stabilize regulation.

Control is executed through the ADJ pin, which accepts DC voltage (0.3–2.5V) or PWM signals to modulate the internal comparator's reference level. The integrated third-order 4kHz low-pass filter enables smooth analog dimming and defines soft-start behavior (500µs base, +0.5ms/nF with external capacitor), while the shutdown circuit activates below 0.2V to reduce quiescent current to 15µA.

Key Specifications

Pinout & Package

TSOT25 (5-pin thin small-outline transistor) package: 2.9mm × 1.6mm × 0.85mm, lead-free, halogen-free, RoHS-compliant, with exposed pad for thermal enhancement (θJA = 200°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AL8862Q-7 and LM3409QMY/NOPB, the ZXLD1350QET5TA uniquely integrates switching, sensing, and dimming control in a TSOT25 package-offering optimal balance of automotive reliability, 350mA capability, and 100:1 dimming without external components.

Availability

ZXLD1350QET5TA is available at Aetrix Electronics and suitable for automotive lighting, commercial vehicle signage, and industrial panel indicator applications requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle continuity.

Supply support for ZXLD1350QET5TA 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 company specializing in discrete, analog, and mixed-signal solutions for automotive, industrial, computing, and consumer markets.

The ZXLD1350Q belongs to Diodes' automotive-grade LED driver product line, engineered specifically for robust, high-efficiency constant-current regulation in harsh vehicular environments with minimal external components.

FAQ

What is the minimum external current sense resistor (RS) value for ZXLD1350QET5TA?

The minimum RS is 0.27Ω when the ADJ pin is floating, yielding 370mA nominal output current while keeping switch current within the 500mA absolute maximum rating. Using lower RS values risks exceeding LX current limits and triggering thermal shutdown. For higher currents, verify junction temperature rise using θJA = 200°C/W and actual PCB copper area.

Can ZXLD1350QET5TA drive multiple LEDs in series?

Yes - it supports series-connected LEDs as long as total forward voltage (VF) remains below VIN minus diode and switch losses (typically ≤28V at 30V input). The device regulates current, not voltage, so VF variation across LEDs does not affect regulation accuracy. Ensure inductor saturation current exceeds peak LED current plus ripple.

How does the ADJ pin behave during PWM dimming at 100Hz?

At 100Hz PWM, the internal 4kHz low-pass filter causes the ADJ node voltage to swing fully between 0V and the applied high-level voltage. When the ADJ voltage drops below 0.2V, the device enters shutdown mode, turning off LED current completely. This results in true on/off dimming with 100:1 range and minimal color shift, ideal for interior lighting.

Is an external input capacitor mandatory for ZXLD1350QET5TA?

Yes - a minimum 1µF X7R ceramic capacitor is required between VIN and GND, placed as close as possible to the IC. Lower-ESR capacitors improve efficiency and stability; Y5V dielectrics are prohibited due to capacitance drift with voltage and temperature. At low input voltages (<9V) or high source impedance, ≥4.7µF is recommended to maintain regulation during transients.