MM74HC540SJX Equivalent & Substitute Parts

Part Overview

The MM74HC540SJX is a Buffer, Inverting logic IC manufactured by onsemi, featuring 1 element with 8 bits per element and 3-state output capability. This 20-SOP package device operates across a 2V to 6V supply voltage range and is rated for -40°C to 85°C operating temperature. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Logic Type	Buffer, Inverting
Number of Elements	1
Number of Bits per Element	8
Output Type	3-State
Current - Output High, Low	7.8mA, 7.8mA
Voltage - Supply	2V ~ 6V
Operating Temperature	-40°C ~ 85°C (TA)
Mounting Type	Surface Mount
Package / Case	20-SOIC (0.209", 5.30mm Width)
Series	74HC

Substitute Part Grouping Explanation

Substitution for the MM74HC540SJX is determined by matching the following critical parameters: logic type (Buffer, Inverting), element and bit configuration (1 element, 8 bits per element), output type (3-State), output current capability (7.8mA high and low), supply voltage range (2V ~ 6V), and operating temperature range (-40°C ~ 85°C). Package compatibility is secondary; parts with equivalent electrical specifications but different package types or packaging formats may serve as functional substitutes depending on board layout constraints.

The substitute parts are grouped as follows:

Direct Manufacturer Equivalent: SN74HC540NS matches all electrical parameters and operates within the same temperature range, with identical package dimensions.

Similar Manufacturer Parts: CD74HC540M, CD74HC540M96, and SN74HC540DWR share the same logic function and electrical specifications. CD74HC540M96 and SN74HC540DWR feature extended operating temperature range (-55°C ~ 125°C for CD74HC540M96), providing broader environmental capability.

Parametric Equivalent: SN74HC540NSR provides identical electrical performance and temperature rating with alternative packaging format.

Parameter Comparison

Parameter	MM74HC540SJX (onsemi)	SN74HC540NS (TI)	CD74HC540M (Harris)	CD74HC540M96 (TI)	SN74HC540DWR (TI)	SN74HC540NSR (TI)
Logic Type	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting	Buffer, Inverting
Number of Elements	1	1	1	1	1	1
Number of Bits per Element	8	8	8	8	8	8
Output Type	3-State	3-State	3-State	3-State	3-State	3-State
Current - Output High, Low	7.8mA, 7.8mA	7.8mA, 7.8mA	7.8mA, 7.8mA	7.8mA, 7.8mA	7.8mA, 7.8mA	7.8mA, 7.8mA
Voltage - Supply	2V ~ 6V	2V ~ 6V	2V ~ 6V	2V ~ 6V	2V ~ 6V	2V ~ 6V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-55°C ~ 125°C	-55°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	20-SOIC (0.209", 5.30mm)	20-SOIC (0.209", 5.30mm)	20-SOIC (0.295", 7.50mm)	20-SOIC (0.295", 7.50mm)	20-SOIC (0.295", 7.50mm)	20-SOIC (0.209", 5.30mm)
Product Status	Obsolete	Discontinued at DiGi Electronics	Obsolete	Active	Active	Active
RoHS Status	Not specified	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For applications requiring active product status with current manufacturing support, CD74HC540M96 and SN74HC540DWR are the primary selections. Both parts are actively produced by Texas Instruments and maintain ROHS3 compliance.

CD74HC540M96 is suitable for designs requiring extended operating temperature range (-55°C ~ 125°C), providing thermal margin beyond the original MM74HC540SJX specification. This part is available in Tape & Reel packaging with the highest inventory level (10,518 units).

SN74HC540DWR offers identical electrical performance to the MM74HC540SJX within the original temperature range (-40°C ~ 85°C) and is available in Cut Tape & Digi-Reel format with substantial inventory (106,424 units).

SN74HC540NSR provides parametric equivalence with active product status and ROHS3 compliance, suitable for applications where the 20-SO package format is acceptable.

CD74HC540M and SN74HC540NS are discontinued or obsolete and should be considered only when inventory constraints require their use.

Frequently Asked Questions (FAQ)

Q: Can SN74HC540DWR directly replace MM74HC540SJX in existing designs?

A: Yes. SN74HC540DWR matches all electrical parameters (logic type, bit configuration, output current, supply voltage, and operating temperature range) and is pin-compatible. The package width difference (0.295" vs 0.209") requires PCB layout verification to confirm footprint compatibility.

Q: What is the difference between CD74HC540M96 and SN74HC540DWR?

A: Both parts share identical electrical specifications and active product status. CD74HC540M96 features extended operating temperature range (-55°C ~ 125°C) compared to SN74HC540DWR (-40°C ~ 85°C). CD74HC540M96 is supplied in Tape & Reel format; SN74HC540DWR is supplied in Cut Tape & Digi-Reel format.

Q: Is SN74HC540NSR compatible with the original MM74HC540SJX?

A: Yes. SN74HC540NSR is a parametric equivalent with matching electrical specifications and operating temperature range. The 20-SO package has identical dimensions (0.209", 5.30mm width) to the original part, ensuring direct PCB compatibility.

Q: Why do some substitute parts have different package widths?

A: The 74HC540 logic function is manufactured in two standard SOIC package variants: narrow body (0.209", 5.30mm width) and wide body (0.295", 7.50mm width). Both variants are electrically equivalent; package selection depends on PCB footprint design and available board space.

Q: Are all substitute parts RoHS compliant?

A: Most active and recently discontinued parts (SN74HC540NS, CD74HC540M96, SN74HC540DWR, SN74HC540NSR) are ROHS3 compliant. CD74HC540M is RoHS non-compliant. Verify RoHS compliance requirements for your application before final part selection.

Q: Which substitute part has the best availability?

A: SN74HC540DWR has the highest inventory level at 106,424 units, followed by CD74HC540M96 at 10,518 units. Both parts are actively manufactured and suitable for production designs.

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