SN74HC191DT Equivalent & Substitute Parts

Part Overview

The SN74HC191DT is a 4-bit binary counter IC manufactured by Texas Instruments, housed in a 16-SOIC surface mount package. This device functions as a synchronous binary counter with both up and down counting capability, featuring asynchronous reset and positive edge triggering. The part is currently in Last Time Buy status, indicating discontinued production. Alternative equivalent parts are necessary to ensure continued design support and procurement availability for new production runs and long-term supply chain stability.

Key Parameters

Parameter	Value
Manufacturer Part Number	SN74HC191DT
Manufacturer	Texas Instruments
Logic Type	Binary Counter
Number of Bits per Element	4
Direction	Up, Down
Reset	Asynchronous
Timing	Synchronous
Count Rate	24 MHz
Trigger Type	Positive Edge
Voltage - Supply	2 V ~ 6 V
Operating Temperature	-40°C ~ 85°C
Package / Case	16-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the SN74HC191DT is determined by strict equivalence across the following critical parameters:

Logic Type: Binary Counter (4-bit)
Direction: Up and Down counting capability
Reset: Asynchronous reset function
Timing: Synchronous operation
Trigger Type: Positive Edge
Package / Case: 16-SOIC form factor
Voltage Supply Range: 2 V ~ 6 V compatibility
Mounting Type: Surface Mount

Parts meeting all these criteria are classified as parametric equivalents. Parts from alternative manufacturers meeting identical electrical and mechanical specifications are classified as manufacturer-recommended equivalents. Variations in count rate or operating temperature range do not disqualify substitution when all core functional parameters remain identical.

Parameter Comparison

Parameter	SN74HC191DT (Main)	SN74HC191DR (Equivalent)	74HC191D,653 (Equivalent)
Manufacturer	Texas Instruments	Texas Instruments	Nexperia USA Inc.
Logic Type	Binary Counter	Binary Counter	Binary Counter
Number of Bits per Element	4	4	4
Direction	Up, Down	Up, Down	Up, Down
Reset	Asynchronous	Asynchronous	Asynchronous
Timing	Synchronous	Synchronous	Synchronous
Count Rate	24 MHz	24 MHz	39 MHz
Trigger Type	Positive Edge	Positive Edge	Positive Edge
Voltage - Supply	2 V ~ 6 V	2 V ~ 6 V	2 V ~ 6 V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 125°C
Package / Case	16-SOIC (0.154", 3.90mm Width)	16-SOIC (0.154", 3.90mm Width)	16-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Product Status	Last Time Buy	Active	Active

Engineering Selection Recommendations

The SN74HC191DT is designated Last Time Buy status, making immediate transition to active alternatives necessary for ongoing production support.

SN74HC191DR is the direct parametric equivalent from Texas Instruments, maintaining identical electrical specifications and operating temperature range. This part is currently in active production status with higher inventory availability (5075 pcs vs. 1002 pcs for the main part).

74HC191D,653 from Nexperia USA Inc. is the manufacturer-recommended equivalent, offering identical core functionality with enhanced performance characteristics. This part features a higher count rate (39 MHz vs. 24 MHz) and extended operating temperature range (-40°C ~ 125°C vs. -40°C ~ 85°C), providing additional design margin for temperature-sensitive applications. All compliance certifications (ROHS3, MSL 1, REACH Unaffected) are maintained.

Both substitute parts are pin-compatible and functionally interchangeable within the 16-SOIC package footprint. Selection between SN74HC191DR and 74HC191D,653 depends on manufacturer preference, inventory requirements, and application temperature operating conditions.

Frequently Asked Questions (FAQ)

Q: Can SN74HC191DR be used as a direct replacement for SN74HC191DT?

A: Yes. SN74HC191DR is a parametric equivalent with identical electrical specifications, operating temperature range, and package configuration. The parts are pin-compatible and functionally interchangeable.

Q: What is the difference between SN74HC191DR and 74HC191D,653?

A: Both parts are functionally equivalent 4-bit binary counters with identical core specifications. The 74HC191D,653 offers a higher maximum count rate (39 MHz vs. 24 MHz) and extended operating temperature range (-40°C ~ 125°C vs. -40°C ~ 85°C). Both maintain identical supply voltage range and package form factor.

Q: Are all three parts compatible with the same PCB layout?

A: Yes. All three parts use the 16-SOIC (0.154", 3.90mm Width) surface mount package with identical pin assignments and footprint requirements.

Q: Why is the SN74HC191DT in Last Time Buy status?

A: Last Time Buy status indicates the manufacturer has discontinued production. SN74HC191DR and 74HC191D,653 are active production alternatives ensuring continued supply chain availability.

Q: Do the substitute parts meet the same compliance requirements?

A: Yes. Both SN74HC191DR and 74HC191D,653 are ROHS3 Compliant, MSL 1 (Unlimited), and REACH Unaffected, matching the compliance profile of the SN74HC191DT.

Q: Which substitute part should be selected for new designs?

A: For new designs, either SN74HC191DR or 74HC191D,653 is acceptable. SN74HC191DR maintains exact specification parity with the original part. 74HC191D,653 provides enhanced performance headroom with higher count rate and extended temperature range, suitable for demanding applications.

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