TD62003AG

Updated: 2026-11-07

Overview

The TD62003AG is a monolithic Darlington transistor array manufactured by Toshiba, integrating seven high-current, high-voltage channels in a compact SOP-18 package. Designed as an interface between low-power logic circuits (TTL, CMOS) and heavy loads, it finds widespread use in factory automation, automotive control units, and appliance control boards. Each channel consists of two cascaded bipolar transistors with a common emitter configuration, delivering current gains up to 10,000 while requiring minimal input current (1-10mA).

Structure and Working Principle

The IC's architecture features seven independent Darlington pairs with shared power (Vcc) and ground connections. Each input channel triggers a two-stage transistor amplifier: the first stage (pre-driver) accepts low-current logic signals (3-5V), while the second stage (output driver) switches up to 500mA at 50V. Built-in suppression diodes across each output protect against back-EMF from inductive loads like relays. The device operates in saturation mode when activated, with typical collector-emitter saturation voltages of 1.6V at 500mA loads. Package thermal considerations are critical - the SOP-18's θJA (junction-to-ambient thermal resistance) of 60°C/W requires PCB copper pours or heat sinks for sustained high-current applications. The chip includes input resistors (2.7kΩ typical) for direct microcontroller interfacing, eliminating external components in most designs.

Key Features

The TD62003AG distinguishes itself with several industry-favored characteristics. Its 50V output withstand voltage rating covers most 12V/24V automotive and industrial systems, while the 500mA per-channel capacity directly drives small relays without additional power transistors. The integrated freewheeling diodes simplify circuit design by eliminating external protection components for inductive loads. An extended operating temperature range (-40°C to +85°C) ensures reliability in harsh environments. Compared to earlier Darlington arrays like the ULN2003A, the TD62003AG offers improved thermal performance due to its surface-mount package and lower saturation voltages. However, designers should note that all seven channels share common power rails, requiring careful PCB layout to prevent cross-talk in sensitive applications. The device's input thresholds are TTL-compatible (2.0V max for 'low', 0.8V min for 'high'), making it versatile for various logic families.

Application Areas

Industrial automation systems extensively utilize the TD62003AG for PLC output modules, where it drives solenoid valves, contactors, and indicator lamps. In automotive electronics, it appears in body control modules for power windows, seat adjusters, and lighting controls. Appliance manufacturers incorporate it into washing machine motor controls, refrigerator defrost timers, and microwave oven display interfaces. Another common use case involves LED matrix driving, where multiple TD62003AGs handle column/row switching for large displays. The device's 0.5μs typical switching speed makes it suitable for multiplexed applications. In test equipment, it serves as a general-purpose interface between digital controllers and high-current peripheral devices. When stacked in parallel (outputs connected), the IC can handle currents beyond 500mA per load, though proper thermal management becomes essential.

Maintenance and Precautions

Proper handling begins with ESD precautions during installation - although the TD62003AG includes some input protection, operators should use grounded wrist straps when handling the SOP-18 package. In operation, ensure the power supply voltage doesn't exceed 50V, and derate current capacity by approximately 10% per 10°C above 25°C ambient temperature. For relay driving applications, position suppressor diodes (if external ones are added) as close as possible to the load terminals. Common failure modes include thermal runaway under sustained overload conditions and input resistor degradation from voltage transients. When troubleshooting, measure output saturation voltage under load - readings significantly above 2V may indicate damaged Darlingtons. The IC's open-collector outputs require pull-up resistors when interfacing with certain logic families, though most loads provide the necessary current path automatically.

B2B Procurement Guide

Industrial buyers should specify the exact suffix (AG for SOP-18, AP for DIP-18) to avoid package mismatches. Minimum order quantities typically start at 1,000 pieces for standard pricing, with lead times ranging from 4-12 weeks depending on market conditions. Verify authenticity through authorized distributors like Avnet or Arrow, as counterfeit devices may lack proper thermal performance. For long-term projects, consider alternate sources like the STMicroelectronics ULN2003A (pin-compatible but with different thermal characteristics) to mitigate supply chain risks. Sample requests are generally available for engineering evaluation, but require NDAs for full datasheet access in some regions. Price breaks commonly occur at 10k, 50k, and 100k unit quantities, with variations based on annual commitment volumes.