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74VHCT138AM Equivalent & Substitute Parts
Part Overview
The 74VHCT138AM is a decoder/demultiplexer integrated circuit manufactured by onsemi, featuring a 1 x 3:8 logic configuration in a 16-SOIC surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.
The 74VHCT138AM operates as a single-supply decoder with 8mA output drive capability across both high and low states. It is designed for applications requiring address decoding and signal demultiplexing in digital logic circuits.
Substiute Parts
Key Parameters
| Parameter | Value |
|---|---|
| Manufacturer | onsemi |
| Base Product Number | 74VHCT138 |
| Type | Decoder/Demultiplexer |
| Circuit Configuration | 1 x 3:8 |
| Current - Output High, Low | 8mA, 8mA |
| Voltage Supply | 4.5V ~ 5.5V (Single Supply) |
| Operating Temperature | -40°C ~ 85°C |
| Package / Case | 16-SOIC (0.154", 3.90mm Width) |
| Mounting Type | Surface Mount |
| Product Status | Obsolete |
| Moisture Sensitivity Level (MSL) | 1 (Unlimited) |
Substitute Part Grouping Explanation
Substitution of the 74VHCT138AM is determined by the following critical parameters:
Electrical Compatibility:
- Decoder/Demultiplexer type with 1 x 3:8 circuit configuration
- Output current capability: 8mA minimum for both high and low states
- Supply voltage range: 4.5V ~ 5.5V
- Operating temperature range: minimum -40°C support required
Mechanical Compatibility:
- Package type: 16-SOIC or equivalent surface mount packages (16-TSSOP, 16-SO acceptable)
- Pin count: 16 pins
- Lead pitch and body width must accommodate PCB layout constraints
Compliance & Status:
- RoHS3 compliance preferred for new designs
- Active or Last Time Buy status preferred over obsolete
Substitute parts are grouped into three categories:
Direct Substitutes (Pin-Compatible, Same Package): Parts maintaining identical electrical specifications and 16-SOIC packaging.
Similar Substitutes (Functional Equivalents, Alternative Packages): Parts with identical electrical specifications but different surface mount packages (16-TSSOP, 16-SO).
Upgrade Substitutes (Enhanced Specifications): Parts with extended operating temperature ranges or automotive qualification while maintaining core electrical compatibility.
Parameter Comparison
| Part Number | Manufacturer | Series | Package | Output Current (mA) | Supply Voltage | Operating Temp (°C) | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|---|
| 74VHCT138AM | onsemi | 74VHCT | 16-SOIC | 8, 8 | 4.5V ~ 5.5V | -40 ~ 85 | Obsolete | Not specified |
| 74VHCT138AMTCX | onsemi | 74VHCT | 16-TSSOP | 8, 8 | 4.5V ~ 5.5V | -40 ~ 85 | Active | ROHS3 Compliant |
| MC74VHCT138ADR2G | onsemi | 74VHCT | 16-SOIC | 8, 8 | 4.5V ~ 5.5V | -55 ~ 125 | Active | ROHS3 Compliant |
| SN74AHCT138DR | Texas Instruments | 74AHCT | 16-SOIC | 8, 8 | 4.5V ~ 5.5V | -40 ~ 85 | Active | ROHS3 Compliant |
| SN74LV138ATD | Texas Instruments | 74LV | 16-SOIC | 12, 12 | 4.5V ~ 5.5V | -40 ~ 125 | Last Time Buy | ROHS3 Compliant |
| 74AHCT138D,118 | Nexperia USA Inc. | 74AHCT | 16-SO | 8, 8 | 4.5V ~ 5.5V | -40 ~ 125 | Active | ROHS3 Compliant |
| 74AHCT138D-Q100J | Nexperia USA Inc. | 74AHCT | 16-SO | 8, 8 | 4.5V ~ 5.5V | -40 ~ 125 | Active | ROHS3 Compliant |
| SN74AHCT138MDREP | Texas Instruments | 74AHCT | 16-SOIC | 8, 8 | 4.5V ~ 5.5V | -55 ~ 125 | Active | ROHS3 Compliant |
| SN74AHCT138NSR | Texas Instruments | 74AHCT | 16-SO | 8, 8 | 4.5V ~ 5.5V | -40 ~ 85 | Active | ROHS3 Compliant |
| SN74AHCT138QDRQ1 | Texas Instruments | 74AHCT | 16-SOIC | 8, 8 | 4.5V ~ 5.5V | -40 ~ 125 | Active | ROHS3 Compliant |
| SN74AHCT138D | Texas Instruments | 74AHCT | 16-SOIC | 8, 8 | 4.5V ~ 5.5V | -40 ~ 85 | Discontinued at DiGi Electronics | ROHS3 Compliant |
Engineering Selection Recommendations
For Direct Pin-Compatible Replacement (16-SOIC Package):
SN74AHCT138DR (Texas Instruments) or SN74AHCT138MDREP (Texas Instruments) are the primary selections. Both maintain identical electrical specifications to the 74VHCT138AM with active product status and ROHS3 compliance. SN74AHCT138MDREP offers extended operating temperature range (-55°C ~ 125°C) for applications requiring broader thermal performance.
For Extended Temperature Range Applications:
MC74VHCT138ADR2G (onsemi) provides the same 74VHCT series lineage with extended operating temperature (-55°C ~ 125°C) while maintaining 16-SOIC packaging and active status.
For Alternative Package Formats:
74VHCT138AMTCX (onsemi) offers 16-TSSOP packaging with active status and ROHS3 compliance, suitable for space-constrained designs. 74AHCT138D,118 (Nexperia USA Inc.) provides 16-SO packaging with extended temperature range (-40°C ~ 125°C).
For Automotive Applications:
74AHCT138D-Q100J (Nexperia USA Inc.) and SN74AHCT138QDRQ1 (Texas Instruments) include AEC-Q100 automotive qualification with extended operating temperature ranges.
Avoid:
SN74LV138ATD is classified as Last Time Buy and features higher output current (12mA vs. 8mA), making it suitable only for applications specifically requiring increased drive capability. SN74AHCT138D is discontinued at DiGi Electronics and should not be selected for new designs.
Frequently Asked Questions (FAQ)
Q: Can I use SN74LV138ATD as a direct replacement for 74VHCT138AM?
A: SN74LV138ATD is functionally compatible but not a direct replacement. It features higher output current (12mA vs. 8mA) and is classified as Last Time Buy. Use only if your application specifically requires the increased output drive capability and you have confirmed long-term availability.
Q: What is the difference between 16-SOIC and 16-TSSOP packages?
A: Both are 16-pin surface mount packages with different body dimensions. 16-SOIC has a 0.154" width, while 16-TSSOP has a 0.173" width. They are not mechanically interchangeable on the same PCB layout. Verify your PCB footprint before selecting an alternative package.
Q: Are all substitute parts ROHS3 compliant?
A: All active substitute parts listed are ROHS3 compliant. The original 74VHCT138AM does not specify RoHS status due to its obsolete classification.
Q: Which substitute offers the widest operating temperature range?
A: MC74VHCT138ADR2G and SN74AHCT138MDREP both support -55°C ~ 125°C operating temperature, compared to the original -40°C ~ 85°C range.
Q: Can I use automotive-qualified parts (AEC-Q100) in non-automotive applications?
A: Yes. Automotive-qualified parts meet or exceed standard commercial specifications and are suitable for any application. 74AHCT138D-Q100J and SN74AHCT138QDRQ1 are valid selections for general-purpose use.
Q: What is the inventory status for these substitutes?
A: All listed substitutes show active inventory availability. 74VHCT138AMTCX has the highest stock level (15,300 pcs), while SN74AHCT138MDREP has the lowest (871 pcs). Verify current availability with your supplier before finalizing procurement.
Q: Are there any electrical performance differences between the 74VHCT and 74AHCT series?
A: Both series maintain identical output current specifications (8mA) and supply voltage requirements (4.5V ~ 5.5V) for this decoder configuration. The primary difference is manufacturer and available temperature/qualification options.
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