Diodes Incorporated ZXLD1100H6TA

Overview

ZXLD1100H6TA from Diodes Incorporated (formerly Zetex) is a PFM inductive boost converter IC designed to drive 2–4 white LEDs in series from a Li-ion cell (2.5–5.5V input), delivering up to 50mA output current with internal 30V NDMOS switch, integrated peak current sense, and open-circuit protection. It operates in discontinuous conduction mode with adjustable analog dimming via PWM on the EN pin and supports up to 28V output voltage for portable backlighting applications.

For engineers reviewing the ZXLD1100H6TA datasheet, ZXLD1100H6TA pinout, ZXLD1100H6TA application, or ZXLD1100H6TA equivalent, key selection criteria include its SC70-6 package footprint, true analog dimming capability via filtered PWM, 100mV FB reference voltage for precise current setting, and internal avalanche diode-based open-circuit protection eliminating external Zener requirements.

Technical Context

The ZXLD1100H6TA implements a self-oscillating PFM control loop that regulates LED current by sensing voltage across an external resistor at the FB pin against a 100mV internal reference. Its internal 30V NDMOS switch and integrated current-sense resistor enable minimal external component count while maintaining stable operation in discontinuous mode.

Open-circuit protection is achieved via an internal avalanche diode between VSENSE and FB pins-when VSENSE is connected to the output, the diode clamps voltage at ~25–30V during open load, limiting stress on the switch and external components. The EN pin serves dual roles: device enable and PWM-controlled dimming input, with internal 4kHz low-pass filtering enabling flicker-free analog dimming at ≥10kHz PWM frequencies.

Key Specifications

Pinout & Package

Supplied in a low-profile SC70-6 package (2.0mm × 1.25mm × 0.9mm), compatible with standard SMT reflow processes and space-constrained mobile PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP5724FDCG-7 and AL8805W5-7, the ZXLD1100H6TA delivers superior integration for low-to-mid current portable backlighting-its internal 30V switch, 100mV FB reference, and open-circuit clamping eliminate four external components while enabling flicker-free dimming with a single EN-pin PWM signal.

Availability

ZXLD1100H6TA is available at Aetrix Electronics and suitable for mobile phone LCD backlighting, digital camera display modules, PDA main displays, and portable internet appliance keypad illumination requiring stable component supply and long-term lifecycle support.

Supply support for ZXLD1100H6TA 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 acquired Zetex Semiconductors in 2008 and maintains its portfolio of high-performance analog and power management ICs for portable and industrial applications.

The ZXLD1100 belongs to Zetex's legacy LED driver product line, engineered specifically for space-constrained, battery-powered backlighting systems demanding high integration, low quiescent current, and robust fault protection.

FAQ

What is the recommended inductor value for ZXLD1100H6TA in a 3-LED, 15mA backlight design?

A 10µH inductor (e.g., Coilcraft DO1608-103 or Sumida CMD4D11-100MC) is optimal for 3-white-LED operation at 15mA from 3.0V input. This value balances switching frequency (~600kHz), efficiency (~80%), and physical size (1mm height). Inductor DCR should be ≤0.5Ω to minimize conduction loss, and saturation current rating must exceed 320mA peak.

How does the ZXLD1100H6TA achieve flicker-free analog dimming without external filtering components?

The IC integrates a 4kHz low-pass filter on the EN pin input. When a ≥10kHz PWM signal is applied, the internal filter produces a stable DC control voltage equal to (PWM duty cycle) × 100mV, which directly modulates the FB reference level-resulting in smooth, continuous LED current reduction without visible flicker or external RC networks.

Can the ZXLD1100H6TA drive more than 4 white LEDs from a 3.7V Li-ion cell?

Yes-when supplied from 5V (e.g., USB or regulated rail), it can drive up to 8 white LEDs (8 × 3.2V = 25.6V), staying within its 28V normal output limit. From a 3.7V Li-ion cell, maximum is 4 LEDs (4 × 3.2V = 12.8V); attempting 5+ LEDs risks insufficient headroom for regulation and reduced efficiency due to increased duty cycle and conduction losses.

What happens during an open-circuit condition, and how does the internal protection respond?

When the LED string opens, VSENSE (if connected to output) rises until the internal avalanche diode conducts (~25–30V), clamping the output and overriding the FB control loop. Supply current drops to <1mA, preventing damage to the 30V NDMOS switch or external components-no external Zener diode is needed, simplifying design and improving reliability.