Diodes Incorporated ZXSC440X8TA

Overview

ZXSC440X8TA from Diodes Incorporated is a DC-DC boost switching controller in MSOP-8 package, designed to drive external NPN or MOSFET transistors for high-voltage step-up conversion. It supports 1.65V–8V input, delivers up to 300mA output current, features ±1% output regulation, 4.5µA shutdown current, and integrates both shutdown (STDN) and end-of-regulation (EOR) flags-enabling battery-powered LED driving and photoflash capacitor charging.

For engineers reviewing the ZXSC440X8TA datasheet, ZXSC440X8TA pinout, ZXSC440X8TA application, or ZXSC440X8TA equivalent, key selection criteria include its dual-flag functionality (STDN + EOR), 28mV current-sense threshold, 300mV feedback reference, 200kHz operating frequency, and compatibility with discrete high-gain Zetex transistors for efficiency-critical portable power designs.

Technical Context

The ZXSC440X8TA implements a fixed-frequency, current-mode boost controller architecture using two internal comparators (Comp1 for voltage feedback, Comp2 for current sensing), a retriggerable monostable, and dynamic gate drive with 2.5mA source capability. Its 28mV sense threshold and 300mV VFB reference are derived from a temperature-compensated bandgap reference (1.22V nominal).

It combines ZXSC410's shutdown control and ZXSC420's EOR flag into one device: STDN enables PWM dimming or system-level enable/disable, while EOR asserts low after >120µs of undervoltage-providing precise battery end-of-life detection or photoflash charge-complete signaling.

Key Specifications

Pinout & Package

ZXSC440X8TA is housed in an MSOP-8 package (3.0mm × 3.0mm × 1.0mm, 0.65mm pitch), thermally enhanced with exposed pad (EP) connected to GND for improved power dissipation in compact battery-powered layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost controller applications.

Compared with MAX17064ETA+ and TPS61040DRVR, ZXSC440X8TA uniquely provides discrete switch flexibility, dual-status flagging (STDN + EOR), and ultra-low shutdown current-making it optimal for battery-gauge-integrated, high-reliability portable systems requiring both control and diagnostics.

Availability

ZXSC440X8TA is available at Aetrix Electronics and suitable for LCD bias generation, high-brightness LED driving, photoflash charging, and portable instrumentation power rails requiring stable component supply and long-term lifecycle support.

Supply support for ZXSC440X8TA 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, with leadership in high-efficiency power management and precision signal conditioning.

ZXSC440X8TA belongs to the Zetex DC-DC boost controller product line, engineered specifically for ultra-low-power, battery-operated portable electronics requiring flexible external switch selection and intelligent regulation monitoring.

FAQ

What external transistor types are recommended for use with ZXSC440X8TA?

Diodes recommends Zetex-brand high-gain NPN transistors such as ZXTN25012EFH (VCEO = 45V, hFE > 250 @ 100mA) or logic-level MOSFETs like DMN2004K (RDS(on) = 0.12Ω). Bipolar devices provide higher gain for low-VCC operation; MOSFETs reduce base drive loss at higher currents. Selection must ensure VCEO/VDS exceeds maximum expected output voltage plus margin.

How does the EOR flag behave during input voltage droop?

EOR remains high-impedance while regulation is maintained. When input voltage drops sufficiently that output can no longer be sustained, EOR transitions low after ≥120µs of continuous undervoltage-acting as a debounced battery exhaustion indicator. It does not respond to sub-120µs transients, ensuring robustness against load spikes or brief brownouts.

Can ZXSC440X8TA regulate constant current for LED strings without additional components?

Yes: connect a single resistor between VFB and GND to set LED current as ILED = 300mV / R. For example, a 10Ω resistor yields 30mA. This configuration uses the internal 300mV reference directly-no op-amp or current-sense amplifier required-making it ideal for simple, low-BOM-cost LED drivers.

Is the MSOP-8 package of ZXSC440X8TA thermally adequate for 300mA output applications?

Yes-the MSOP-8 with exposed pad (EP) achieves θJA ≈ 120°C/W under standard 2-layer PCB conditions (1in² copper, 1oz, 2 thermal vias to inner ground plane). At 300mA output with 85% efficiency and 3.6V input, power dissipation is ~180mW, resulting in <22°C junction rise above ambient-well within the +85°C max operating temperature limit.