Texas Instruments SN75469D

Overview

SN75469D from Texas Instruments is a 7-channel high-voltage Darlington transistor array optimized for driving inductive loads such as relays, solenoids, and lamps. It features 100 V collector-emitter voltage rating, 500 mA per channel collector current capability, integrated common-cathode clamp diodes, and 10.5 kΩ input base resistors enabling direct interface with 6–15 V CMOS/PMOS logic. It operates across –40°C to 125°C junction temperature range.

For engineers reviewing the SN75469D datasheet, SN75469D pinout, SN75469D application, or SN75469D equivalent, key selection criteria include its 10.5 kΩ input resistor value (vs. SN75468's 2.7 kΩ), 100 V output clamping, 500 mA per-channel sink capability, thermal resistance (RθJA = 73°C/W in SOIC-16), and compatibility with higher-voltage logic families.

Technical Context

The SN75469D integrates seven independent NPN Darlington pairs, each with a dedicated 10.5 kΩ series base resistor-designed specifically for direct drive from 6–15 V CMOS or PMOS logic without external biasing. Its open-collector outputs share a common emitter (Pin 7) and connect to a shared cathode clamp node (Pin 8) for flyback energy suppression.

This architecture enables robust inductive load switching while maintaining low input current draw (e.g., ~0.5 mA at 5 V, ~1.45 mA at 12 V). The device does not require an external power supply for logic interface; only the COM pin (Pin 8) must be tied to the inductive load's supply rail to activate internal clamp diodes.

Key Specifications

Pinout & Package

SN75469D is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.91 mm, with 1.27 mm lead pitch and 2.00 mm max height. Pin 1 is marked by a notch or bevel on the package top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington array applications.

Compared with ULN2004A, SN75469D provides 2× higher voltage headroom for industrial inductive loads; compared with SN75468D, it delivers 4× lower input current at 12 V, enabling direct interface with battery-powered PMOS logic without level shifters.

Availability

SN75469D is available at Aetrix Electronics and suitable for relay drivers, lamp drivers, LED display interfaces, and industrial line drivers requiring stable component supply across extended temperature and voltage ranges.

Supply support for SN75469D 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

Texas Instruments is a global semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.

The SN75469D belongs to TI's legacy Darlington transistor array product line, designed specifically for robust, low-component-count interface between modern logic devices and high-voltage/high-current electromechanical loads.

FAQ

What is the maximum continuous collector current per channel for SN75469D?

The SN75469D is rated for 500 mA per channel under recommended operating conditions. This rating assumes proper PCB thermal design (e.g., ≥1 in² copper pour) and ambient temperature ≤70°C. At higher temperatures or reduced copper area, derating per the RθJA = 73°C/W thermal metric is required to maintain junction temperature ≤125°C. The SN75469D datasheet confirms this value in Section 7.1 Absolute Maximum Ratings and Figure 4 (D Package Maximum Collector Current vs Duty Cycle).

Can SN75469D drive a 24 V relay coil directly?

Yes, SN75469D can directly drive a 24 V relay coil. Its 100 V V_CE rating and integrated clamp diodes (activated when COM pin is tied to the 24 V rail) provide full protection against flyback voltage. For a typical 24 V, 200 Ω relay coil drawing 120 mA, the SN75469D's V_CE(sat) of ≤1.6 V (per Section 7.5 Electrical Characteristics) ensures minimal power loss (≈0.19 W/channel). Always verify coil current remains within the 500 mA limit and thermal limits under your duty cycle.

How does SN75469D differ from SN75468D in practical circuit design?

The core difference lies in input resistor value: SN75469D uses 10.5 kΩ resistors, while SN75468D uses 2.7 kΩ. This makes SN75469D suitable for 6–15 V CMOS/PMOS logic (input current ≤1.45 mA at 12 V), whereas SN75468D targets 3.3–5 V TTL/CMOS (input current ≈1.85 mA at 5 V). Using SN75468D with 12 V logic risks excessive input current and potential damage; SN75469D is the correct choice for higher-voltage logic interfaces.

Is a heat sink required for SN75469D in continuous 500 mA operation?

A dedicated heat sink is not required, but substantial PCB copper area is essential. With RθJA = 73°C/W, dissipating 0.69 W (500 mA × 1.38 V_CE(sat)) raises junction temperature by ≈50°C above ambient. At 70°C ambient, this reaches 120°C - near the 125°C limit. TI recommends ≥1 in² of 2-oz copper connected to Pin 7 (E) and Pin 8 (COM) for continuous full-load operation. No external heat sink is specified in the datasheet, but thermal vias to inner layers improve performance.

What is the function of the COM pin (Pin 8) on SN75469D?

The COM pin (Pin 8) is the common cathode node for all seven internal clamp diodes. When driving inductive loads, COM must be connected to the positive supply rail of the load (e.g., +24 V). This allows stored magnetic energy to recirculate safely through the diode during transistor turn-off, preventing voltage spikes >100 V. If COM is left floating or grounded, clamp diodes cannot conduct, risking destructive voltage overshoot. For resistive loads, COM may be left unconnected, but output pull-ups remain necessary.