Diodes Incorporated ZXLD1374QEV1

Overview

ZXLD1374QEV1 from Diodes Incorporated is an evaluation board for the ZXLD1374Q 1.5A buck LED driver IC, designed to demonstrate constant-current LED driving from 8–48V input with thermal foldback and analog/PWM dimming control. It supports up to 15 series LEDs at 1.5A, features TSSOP-20EP package mounting, open-drain status output, and adjustable current via ADJ (125mV–2.5V) and TADJ (625mV thermal threshold) pins.

For engineers reviewing the ZXLD1374QEV1 datasheet, ZXLD1374QEV1 pinout, ZXLD1374QEV1 application, or ZXLD1374QEV1 equivalent, this board enables rapid validation of ZXLD1374Q-based LED driver designs in automotive lighting, industrial signage, and high-brightness display backlighting where input voltage range, thermal derating, and dual-dimming interface are critical.

Technical Context

The ZXLD1374QEV1 implements a fixed-frequency hysteresis-controlled buck topology using an internal 1.5A NMOS switch and external freewheeling diode (SBR3U100LP). Current sensing relies on parallel 0.3Ω resistors (R1//R2 = 0.15Ω), setting nominal LED current at 1.5A via 125mV threshold.

Thermal regulation is implemented via the TADJ pin with a 1k3 resistor (R4) and optional 10k NTC thermistor, enabling linear current reduction above ~90°C. Analog dimming uses the ADJ pin (125mV–2.5V = 10%–200% I_LED), while PWM dimming accepts logic-level signals on the dedicated PWM pin with shutdown capability below 0.4V for >15ms.

Key Specifications

Availability

ZXLD1374QEV1 is available at Aetrix Electronics and suitable for automotive headlight prototypes, industrial LED signage qualification, and high-reliability display backlight development requiring stable component supply and validated reference design integration.

Supply support for ZXLD1374QEV1 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 power management, signal integrity, and LED driver solutions for industrial, automotive, and consumer applications.

The ZXLD1374Q product line delivers high-efficiency, thermally robust constant-current LED drivers targeting mid-to-high power lighting where input voltage variation and thermal reliability are design-critical.

FAQ

What is the purpose of the 'TADJ' pin on the ZXLD1374QEV1?

The TADJ pin monitors temperature via an external NTC thermistor network and linearly reduces LED current when the sensed voltage drops below 625mV-corresponding to a thermal threshold (~90°C with R4=1.3kΩ and 10k NTC). This prevents LED overheating without requiring external microcontroller intervention.

Can the ZXLD1374QEV1 drive more than 15 LEDs?

No-the board's 33µH inductor (MSS1278-333MLB), 100V-rated capacitors, and SBR3U100LP diode are rated for ≤15-series white LEDs (max ~67.5V total V_f). Exceeding this risks inductor saturation, capacitor overstress, and insufficient headroom for the 48V max input.

How is analog dimming implemented on this evaluation board?

Analog dimming is enabled by applying 125mV–2.5V to the ADJ pin, which scales LED current from 10% to 200% of nominal 1.5A. On the ZXLD1374QEV1, R3 shorts ADJ to VREF for full current; removing R3 and applying an external voltage via R5 achieves precise DC current adjustment.

Does the ZXLD1374QEV1 include ESD or surge protection?

No-this evaluation board lacks dedicated TVS diodes, input filters, or ESD protection components. It assumes use in controlled lab environments. For production deployment, external 48V-rated bidirectional TVS (e.g., SMAJ48A) and input bulk capacitance must be added per IEC 61000-4-5 requirements.