Texas Instruments SN75468DR

Overview

SN75468DR from Texas Instruments is a 7-channel high-voltage NPN Darlington transistor array with 500-mA per-channel sink capability, 100-V output rating, integrated common-cathode clamp diodes, and 2.7-kΩ input base resistors enabling direct TTL/CMOS (3.3 V or 5 V) drive. It serves as an industrial interface buffer for inductive load switching in relay, solenoid, and lamp driver circuits.

For engineers reviewing the SN75468DR datasheet, SN75468DR pinout, SN75468DR application, or SN75468DR equivalent, key selection criteria include per-channel current derating at elevated ambient temperature, thermal resistance (R_θJA = 73 °C/W in SOIC), COM pin voltage alignment with inductive supply rails, and parallel-output configuration for >500-mA loads.

Technical Context

The SN75468DR integrates seven independent Darlington pairs, each formed by cascaded NPN transistors delivering current gain up to 10,000 A/A. Its 2.7-kΩ series input resistor sets nominal input current at 1.85 mA at 5 V, enabling direct logic-level interfacing without external biasing.

Each channel features open-collector outputs tied to a shared emitter (E) and a common cathode node (COM) for flyback diode clamping. The device operates across –40°C to 125°C junction temperature with absolute maximum V_CE = 100 V and peak collector current = 500 mA per channel.

Key Specifications

Pinout & Package

SN75468DR is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.91 mm with 1.27-mm lead pitch. The package supports surface-mount reflow (MSL Level-1, 260°C peak).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ULN2003ADR, SN75468DR offers wider operating temperature and identical electrical specs; compared with SN75469DR, it provides lower input threshold and guaranteed 3.3 V compatibility - making SN75468DR the optimal choice for modern embedded designs interfacing 3.3 V microcontrollers to industrial loads.

Availability

SN75468DR is available at Aetrix Electronics and suitable for relay driver modules, industrial lamp controllers, electromagnetic actuator interfaces, and legacy bus line drivers requiring stable component supply across automotive, factory automation, and building management systems.

Supply support for SN75468DR 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 leader specializing in analog, embedded processing, and logic ICs, with over 50 years of industrial interface product development.

The SN75468DR belongs to TI's legacy Darlington array family designed specifically for robust, low-complexity interfacing between low-voltage logic and high-voltage/high-current electromechanical loads in harsh environments.

FAQ

What is the maximum continuous current per channel for SN75468DR?

The SN75468DR is rated for 500 mA continuous collector current per channel under recommended operating conditions (T_J ≤ 125°C). Derating is required above 25°C ambient: at 70°C ambient, maximum per-channel current drops to ~350 mA in SOIC package due to thermal limits (R_θJA = 73 °C/W). Always verify power dissipation using V_CE(sat) and actual load current in your layout.

Can SN75468DR drive 24 V relays directly from a 3.3 V microcontroller?

Yes. SN75468DR's 2.7-kΩ internal base resistors allow direct connection to 3.3 V GPIO pins, drawing ~1.2 mA input current - well within typical MCU output capability. With COM tied to the 24 V relay supply and E grounded, SN75468DR sinks relay coil current while its internal clamp diodes suppress flyback voltage. No external components are needed for basic operation.

How should the COM pin be connected when driving inductive loads with SN75468DR?

For inductive loads (relays, solenoids, hammers), the COM pin must be connected directly to the positive supply rail of the load (e.g., +24 V). This ties the cathodes of all internal clamp diodes to the supply, providing a low-impedance path for flyback current when the Darlington turns off. Connecting COM to GND or leaving it floating disables clamp protection and risks device failure from voltage overshoot.

Is SN75468DR pin-compatible with ULN2003A?

Yes - SN75468DR and ULN2003A share identical 16-pin SOIC (D) package dimensions, pin numbering, and functional pin assignments (inputs 1–7, outputs 10–16, E at pin 7, COM at pin 8). Electrical characteristics are nearly identical, though SN75468DR specifies extended temperature operation (–40°C to 125°C) versus ULN2003A's 0°C to 70°C commercial range.

What is the purpose of the common emitter (E) pin on SN75468DR?

The E pin (pin 7) is the shared emitter connection for all seven Darlington pairs. It must be connected to the system ground reference to complete the current path from each collector output through the load and back to ground. Unlike COM, E carries total emitter current (up to 2.5 A with all channels active), so it requires a wide PCB trace or plane to minimize voltage drop and heating.