LP3944ISQ LED Driver IC Equivalent & Substitute Parts

Part Overview

The LP3944ISQ is an 8-output LED driver power switch IC manufactured by Texas Instruments, designed for camera flash and similar lighting applications. This device integrates a shift register topology with I2C/SMBus dimming control, delivering 25mA per output channel across a 2.3V to 5.5V supply range in a 24-WQFN surface mount package.

The LP3944ISQ is classified as obsolete. Identifying equivalent and substitute parts is necessary to ensure design continuity, maintain supply chain reliability, and support ongoing production requirements for applications currently utilizing this component.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Type	Power Switch
Topology	Shift Register
Number of Outputs	8
Current per Output Channel	25mA
Supply Voltage Range	2.3V to 5.5V
Dimming Interface	I2C, SMBus
Operating Temperature	-40°C to 85°C
Package Type	24-WQFN (4x4) Exposed Pad
Mounting Type	Surface Mount
Applications	Camera Flash

Substitute Part Grouping Explanation

Substitute parts for the LP3944ISQ are identified based on strict electrical and mechanical parameter matching:

Critical Parameters for Substitution:

Number of outputs: 8 channels
Output current capability: 25mA per channel
Supply voltage range: 2.3V to 5.5V
Dimming control: I2C and SMBus compatible
Package: 24-WQFN (4x4) with exposed pad
Topology: Shift register-based power switch
Operating temperature range: -40°C to 85°C

The substitute parts LP3944ISQ/NOPB and LP3944ISQX/NOPB meet all electrical and mechanical specifications of the main part. Both are active products from Texas Instruments with identical functional parameters, differing only in packaging format (Tape & Reel) and compliance certifications.

Parameter Comparison

Parameter	LP3944ISQ	LP3944ISQ/NOPB	LP3944ISQX/NOPB
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments
Product Status	Obsolete	Active	Active
Type	Power Switch	Power Switch	Power Switch
Topology	Shift Register	Shift Register	Shift Register
Number of Outputs	8	8	8
Current per Output Channel	25mA	25mA	25mA
Supply Voltage (Min)	2.3V	2.3V	2.3V
Supply Voltage (Max)	5.5V	5.5V	5.5V
Dimming Control	I2C, SMBus	I2C, SMBus	I2C, SMBus
Operating Temperature	-40°C to 85°C	-40°C to 85°C	-40°C to 85°C
Package	24-WQFN (4x4) Exposed Pad	24-WQFN (4x4) Exposed Pad	24-WQFN (4x4) Exposed Pad
Mounting Type	Surface Mount	Surface Mount	Surface Mount
RoHS Status	RoHS Non-Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	3 (168 Hours)	3 (168 Hours)	3 (168 Hours)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Both LP3944ISQ/NOPB and LP3944ISQX/NOPB are direct functional equivalents to the obsolete LP3944ISQ. Selection between these active alternatives should be based on the following criteria:

LP3944ISQ/NOPB is recommended for applications requiring maximum inventory availability, with 25,200 units in stock. This part carries ROHS3 compliance and is supplied in Tape & Reel packaging format.

LP3944ISQX/NOPB is recommended where extended temperature performance or specific supplier requirements apply. This part also carries ROHS3 compliance with 1,720 units available in Tape & Reel format.

Both substitute parts are active products with identical electrical specifications and package geometry, ensuring direct PCB compatibility with designs originally specified for the LP3944ISQ. The transition from the obsolete part to either active substitute requires no circuit modifications or design changes.

Frequently Asked Questions (FAQ)

Q: Can LP3944ISQ/NOPB and LP3944ISQX/NOPB be used interchangeably with LP3944ISQ?

A: Yes. Both substitute parts are electrically and mechanically identical to the obsolete LP3944ISQ. All critical parameters—output count, current rating, supply voltage range, dimming interface, package type, and operating temperature—are matched. Direct substitution is possible without circuit redesign.

Q: What is the difference between LP3944ISQ/NOPB and LP3944ISQX/NOPB?

A: Both parts are functionally equivalent with identical electrical specifications. The primary differences are product status (both active), inventory levels, and internal manufacturing designations. The "/NOPB" suffix indicates lead-free, RoHS-compliant versions supplied in Tape & Reel packaging.

Q: Why is the original LP3944ISQ classified as obsolete?

A: The LP3944ISQ has reached end-of-life status. Texas Instruments continues to offer the LP3944 family through active product variants LP3944ISQ/NOPB and LP3944ISQX/NOPB, which provide identical functionality with improved compliance certifications.

Q: Are there any package or pinout differences between these parts?

A: No. All three parts use the identical 24-WQFN (4x4) surface mount package with exposed pad. Pinout, footprint, and mechanical dimensions are identical, ensuring direct PCB compatibility.

Q: What compliance certifications apply to the substitute parts?

A: Both LP3944ISQ/NOPB and LP3944ISQX/NOPB are ROHS3 compliant and REACH unaffected. These certifications exceed the non-compliant status of the obsolete LP3944ISQ, supporting modern regulatory requirements.

Q: Can I mix inventory of LP3944ISQ/NOPB and LP3944ISQX/NOPB in production?

A: Yes. Both parts are functionally identical and can be used interchangeably in the same application without performance or compatibility concerns.

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