Texas Instruments SN75468D

Overview

SN75468D from Texas Instruments is a 7-channel high-voltage NPN Darlington transistor array with 500-mA per-channel sink capability, 100-V collector-emitter rating, integrated common-cathode clamp diodes, and 2.7-kΩ input base resistors enabling direct TTL/CMOS (3.3 V or 5 V) interfacing - used in relay drivers, lamp drivers, and inductive load switching.

For engineers reviewing the SN75468D datasheet, SN75468D pinout, SN75468D application, or SN75468D equivalent, key selection considerations include its open-collector Darlington output architecture, thermal derating at elevated ambient temperatures, COM pin voltage dependency for flyback protection, and compatibility with legacy industrial control interfaces requiring robust current sinking.

Technical Context

The SN75468D integrates seven independent Darlington pairs, each formed by cascaded NPN transistors delivering β² current gain up to 10,000, enabling 500 mA output sink with sub-0.5 mA input drive. Its 2.7-kΩ series base resistor sets VI(on) ≈ 3 V and supports direct connection to 3.3 V or 5 V logic without external biasing.

All channels share a common emitter (E) terminal and a common cathode (COM) node for internal clamp diodes, allowing simultaneous suppression of inductive kickback when driving relays or solenoids. The device operates across –40°C to 125°C junction temperature with absolute maximum VCE = 100 V and peak I_C = 500 mA per channel.

Key Specifications

Pinout & Package

SN75468D 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 beveled corner or notch; leads are gull-wing, NiPdAu-plated, and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003A and SN75469D, SN75468D uniquely balances 100 V capability, 3.3/5 V logic compatibility, and SOIC-16 manufacturability - making it the preferred choice for new designs targeting 24–100 V industrial loads with modern low-voltage MCUs.

Availability

SN75468D is available at Aetrix Electronics and suitable for relay drivers, lamp drivers, and inductive load buffers requiring stable component supply across industrial automation, building control, and legacy equipment repair programs.

Supply support for SN75468D 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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and consumer markets.

The SN75468D belongs to TI's legacy Darlington transistor array product line, engineered specifically for robust, low-cost interface between modern logic devices and high-voltage/high-current electromechanical loads in industrial control systems.

FAQ

What is the maximum continuous load voltage the SN75468D can switch?

The SN75468D has an absolute maximum collector-emitter voltage (V_CE) rating of 100 V, meaning it can continuously switch DC loads up to 100 V when operated within recommended conditions. For reliable long-term operation, TI specifies V_CE ≤ 100 V with proper thermal management - confirmed in Section 7.1 of SLRS023E. Derating is required above 70°C ambient.

Can the SN75468D drive multiple relays simultaneously without overheating?

Yes, but thermal limits must be observed: with R_θJA = 73 °C/W, the SN75468D dissipates ~390 mW per channel at 300 mA and V_CE(sat) = 1.3 V. Driving all 7 channels at full 500 mA continuously exceeds its ~1.37 W max power budget at 70°C ambient. TI Figure 4 shows duty-cycle derating - e.g., 100% load possible at ≤200 mA/channel for sustained operation.

How should the COM pin be connected when driving inductive loads?

For inductive load protection, the COM pin must be connected directly to the positive supply rail of the load (e.g., +24 V for a relay coil). This ties the cathodes of all internal clamp diodes to the supply, allowing flyback current to recirculate safely through the diode and coil during turn-off - as specified in Section 9.4.1 and Figure 16 of SLRS023E. Leaving COM floating disables clamp functionality.

Is the SN75468D compatible with 3.3 V microcontroller GPIOs?

Yes - the SN75468D's 2.7-kΩ internal base resistors set VI(on) ≈ 3 V, enabling direct interface with 3.3 V logic. At VI = 3.3 V, input current is ~1.2 mA (per Section 7.5), well within typical MCU GPIO sink capability. No level shifter or external resistor is needed, unlike the SN75469D which requires ≥6 V input.

What is the purpose of the common emitter (E) pin on the SN75468D?

The E pin is the shared emitter connection for all seven Darlington pairs. It must be connected to system ground (0 V reference) to complete the current path from COM → load → collector → emitter → ground. All output current flows through this single terminal, so PCB trace width must support up to 2.5 A if all channels are paralleled - as noted in Section 12.1 layout guidelines.