ULN2004AIN Equivalent & Substitute Parts

Part Overview

The ULN2004AIN is a 7-channel NPN Darlington transistor array manufactured by Texas Instruments, designed for relay and solenoid driver applications. This power switch/driver operates at 50V maximum load voltage with 500mA output current per channel in a 16-DIP through-hole package. The device is classified as Last Time Buy, indicating discontinued production status. Identifying equivalent and substitute parts is essential for design continuity, long-term availability, and alternative sourcing strategies.

Key Parameters

Parameter	Value
Manufacturer Part Number	ULN2004AIN
Manufacturer	Texas Instruments
Number of Outputs	7
Output Type	NPN
Voltage - Load (Max)	50V
Current - Output (Max)	500mA
Ratio - Input:Output	1:1
Output Configuration	Low Side
Input Type	Inverting
Package / Case	16-DIP (0.300", 7.62mm)
Mounting Type	Through Hole
Operating Temperature	-40°C ~ 105°C (TA)
RoHS Status	ROHS3 Compliant
Product Status	Last Time Buy

Substitute Part Grouping Explanation

Substitution eligibility for the ULN2004AIN is determined by the following critical parameters:

Channel Count: 7 outputs (non-negotiable)
Output Type: NPN Darlington configuration
Voltage Rating: 50V maximum load voltage
Current Rating: 500mA maximum output current
Input/Output Ratio: 1:1 configuration
Output Configuration: Low-side switching
Input Logic: Inverting
Package Compatibility: 16-DIP through-hole form factor (primary); 16-SOIC surface mount (secondary with PCB redesign)

Substitute parts are grouped into two categories:

Category 1: Direct Pin-Compatible Substitutes (16-DIP Through-Hole) Parts maintaining identical package, pinout, and electrical specifications, requiring no PCB modifications.

Category 2: Functional Equivalents with Package Variation (16-SOIC Surface Mount) Parts with identical electrical specifications but different package form factor, requiring PCB layout redesign.

Parameter Comparison

Parameter	ULN2004AIN (TI)	ULN2004ADR (TI)	ULN2004A (STM)	ULN2002A (STM)	ULN2001A (STM)	ULQ2004A (STM)	ULQ2003A (STM)	ULQ2001A (STM)	TBD62004APG (Toshiba)	ULN2003A (UMW)
Number of Outputs	7	7	7	7	7	7	7	7	7	7
Output Type	NPN	NPN	NPN	NPN	NPN	NPN Darlington	NPN Darlington	NPN Darlington	N-Channel	Darlington
Voltage - Load (Max)	50V	50V	50V	50V	50V	50V	50V	50V	50V	50V
Current - Output (Max)	500mA	500mA	500mA	500mA	500mA	500mA	500mA	500mA	500mA	500mA
Ratio - Input:Output	1:1	1:1	1:1	1:1	1:1	1:1	1:1	1:1	1:1	1:1
Output Configuration	Low Side	Low Side	Low Side	Low Side	Low Side	Low Side	Low Side	Low Side	Low Side	Low Side
Input Type	Inverting	Inverting	Inverting	Inverting	Inverting	Inverting	Inverting	Inverting	Inverting	Inverting
Package / Case	16-DIP	16-SOIC	16-DIP	16-DIP	16-DIP	16-DIP	16-DIP	16-DIP	16-DIP	16-SOIC
Mounting Type	Through Hole	Surface Mount	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Surface Mount
Operating Temperature	-40°C ~ 105°C	-40°C ~ 70°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 150°C (TJ)	-40°C ~ 150°C (TJ)	-40°C ~ 150°C (TJ)	-40°C ~ 85°C	-40°C ~ 85°C
Product Status	Last Time Buy	Active	Active	Active	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes (16-DIP Through-Hole, No PCB Redesign Required)

For applications requiring direct replacement without PCB modifications, the following active-status parts are recommended:

ULN2004A (STMicroelectronics): Identical electrical specifications and 16-DIP package. Operating temperature range -40°C to 85°C. Highest inventory availability (35,400 units). Recommended for standard relay and solenoid driver applications.
ULN2002A (STMicroelectronics): Functionally equivalent with identical package and electrical ratings. Operating temperature -40°C to 85°C. Lower inventory (2,280 units). Suitable as secondary option.
ULN2001A (STMicroelectronics): Functionally equivalent with identical package and electrical ratings. Operating temperature -40°C to 85°C. Moderate inventory (22,700 units). Suitable for relay driver applications.
ULQ2004A (STMicroelectronics): NPN Darlington array with identical electrical specifications. 16-DIP package. Higher operating temperature capability (150°C junction temperature). Inventory: 2,293 units.
ULQ2003A (STMicroelectronics): NPN Darlington array with identical electrical specifications. 16-DIP package. Higher operating temperature capability (150°C junction temperature). Highest inventory among STM alternatives (18,474 units).
ULQ2001A (STMicroelectronics): NPN Darlington array with identical electrical specifications. 16-DIP package. Higher operating temperature capability (150°C junction temperature). Inventory: 2,100 units.
TBD62004APG (Toshiba Semiconductor): N-Channel power switch with identical electrical specifications and 16-DIP package. Operating temperature -40°C to 85°C. High inventory (12,100 units). Suitable for general-purpose switching applications.

Secondary Substitute (16-SOIC Surface Mount, PCB Redesign Required)

ULN2004ADR (Texas Instruments): Manufacturer-recommended equivalent with identical electrical specifications. 16-SOIC surface-mount package requires PCB layout modification. Operating temperature -40°C to 70°C (narrower range than original). Highest inventory availability (80,213 units). Recommended for new designs or PCB revisions.
ULN2003A (UMW): Surface-mount 16-SOIC package with identical electrical specifications. Operating temperature -40°C to 85°C. High inventory (39,100 units). Suitable for surface-mount design implementations.

Compliance and Certification Status

All substitute parts maintain ROHS3 compliance and EAR99 export classification, consistent with the original ULN2004AIN. REACH status is unaffected for all recommended substitutes.

Frequently Asked Questions (FAQ)

Q: Can I use ULN2004ADR as a direct replacement for ULN2004AIN without modifying my PCB?

A: No. ULN2004ADR uses a 16-SOIC surface-mount package, while ULN2004AIN uses a 16-DIP through-hole package. Direct PCB substitution is not possible without layout redesign. For drop-in replacement, use ULN2004A, ULN2002A, or ULN2001A from STMicroelectronics, or TBD62004APG from Toshiba.

Q: What is the difference between ULN2004A and ULQ2004A?

A: Both are 7-channel NPN Darlington arrays with identical electrical specifications (50V, 500mA, 1:1 ratio, low-side output). The primary difference is operating temperature range: ULN2004A operates -40°C to 85°C (TA), while ULQ2004A operates to 150°C (TJ). ULQ2004A is suitable for higher-temperature environments.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All recommended substitute parts maintain ROHS3 compliance, consistent with the original ULN2004AIN.

Q: Can I substitute TBD62004APG for ULN2004AIN in a relay driver circuit?

A: Yes. TBD62004APG is a functionally equivalent 7-channel power switch with identical electrical specifications (50V load voltage, 500mA output current, 1:1 ratio, low-side configuration, inverting input). It uses the same 16-DIP through-hole package and is suitable for relay and solenoid driver applications.

Q: Why does ULN2004AIN show "Last Time Buy" status?

A: Last Time Buy status indicates Texas Instruments has discontinued production of this part number. Existing inventory is available, but no future production is planned. Substitution to active-status alternatives is recommended for long-term design continuity.

Q: What is the inventory situation for substitute parts?

A: ULN2004ADR (80,213 units) and ULN2003A (39,100 units) have the highest availability. ULN2004A (35,400 units) and ULN2001A (22,700 units) offer strong inventory levels. All recommended substitutes are in active production with stable supply.

Q: Can I use a surface-mount substitute if I redesign my PCB?

A: Yes. ULN2004ADR and ULN2003A are functionally equivalent surface-mount alternatives. PCB redesign is required to accommodate the 16-SOIC package footprint. Both parts maintain identical electrical specifications and ROHS3 compliance.

Q: Are there any electrical performance differences between the substitute parts?

A: All substitute parts meet the same electrical specifications: 7 outputs, 50V maximum load voltage, 500mA maximum output current, 1:1 input/output ratio, low-side output configuration, and inverting input logic. Operating temperature ranges vary; refer to the Parameter Comparison table for specific temperature ratings.

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