SN74LVC138APWR-P Texas Instruments Integrated Circuit (Small Outline Packages) In Stock
SN74LVC138APWR-P is a 3-to-8 line decoder/demultiplexer from Texas Instruments in the LVC low-voltage CMOS logic family, providing active-low decoded outputs for address decoding and data routing. The device operates from 1.65 V to 5.5 V, features three enable inputs for cascading, and delivers fast propagation delays with low power consumption. Packaged in a 16-pin TSSOP, it is widely used for chip-select generation and memory address decoding in embedded systems.
- Manufacturer
- Texas Instruments
- Package
- Small Outline Packages
- Pin Count
- 16
- Lifecycle
- ACTIVE
- Datasheet
- SN74LVC138APWR-P Datasheet PDF
- Category
- Integrated Circuit
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- 3-to-8 line decoder with 8 active-low outputs for address decoding
- Wide supply range 1.65 V to 5.5 V covering 1.8 V, 3.3 V, and 5 V systems
- Three enable inputs (2 active-low, 1 active-high) for cascading up to 5-to-32 decoding
- Fast propagation delay with LVC CMOS low-power operation
- 5 V tolerant inputs allow mixed 3.3 V/5 V system interfacing
- 16-pin TSSOP SMD package for compact PCB layouts
Applications
SN74LVC138APWR-P is used for chip-select decoding and memory address mapping in microcontroller, FPGA, and DSP-based systems operating at 1.8 V, 3.3 V, or 5 V. Its three enable inputs allow multiple devices to be cascaded for larger decode trees, making it a standard choice for peripheral address decoding in industrial control, communication equipment, and embedded computing boards.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for SN74LVC138APWR-P:
Frequently Asked Questions
Over what supply voltage range does SN74LVC138APWR-P operate, and which logic families can it interface with directly?
SN74LVC138APWR-P operates from 1.65 V to 5.5 V, making it compatible with 1.8 V, 2.5 V, 3.3 V, and 5 V logic systems. The LVC family includes 5 V tolerant inputs, so a 3.3 V-powered SN74LVC138APWR-P can accept input signals from legacy 5 V TTL or CMOS address buses without level-shift circuitry, simplifying mixed-voltage address decoder designs.
How can the 3 enable inputs of SN74LVC138APWR-P be used to build a 5-to-32 decoder?
By connecting four SN74LVC138APWR-P devices in a tree configuration, the two active-low enable inputs (E1, E2) and one active-high enable (E3) of each device are driven from the outputs of a higher-level 2-to-4 decoder, producing 32 uniquely selected active-low outputs from a 5-bit address. Each of the 4 SN74LVC138APWR-P devices is enabled by exactly one combination of the upper 2 address bits, while the lower 3 address bits select among its 8 outputs.
Which embedded memory interface applications commonly use SN74LVC138APWR-P for chip-select generation?
SN74LVC138APWR-P is routinely used to generate chip-select signals for SRAM, NOR flash, and peripheral-mapped registers on microcontroller external bus interfaces operating at 3.3 V. When a CPU drives 3 address lines into the decoder, up to 8 separate memory devices or peripheral regions can be independently selected with active-low CS signals, reducing the chip-select logic from multiple discrete gates to a single 16-pin TSSOP device.
Does the TSSOP package of SN74LVC138APWR-P offer any advantage over the DIP version for high-density PCBs?
The 16-pin TSSOP package of SN74LVC138APWR-P has a 0.65 mm pin pitch and occupies less than 25 mm² of board area, compared to approximately 185 mm² for a 16-pin DIP. For high-density embedded boards with multiple decoder, driver, and logic ICs sharing a 3.3 V bus, this roughly 7x footprint reduction allows the chip-select decode tree to fit in the narrow routing channels between larger components such as processors and memory devices.
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About Texas Instruments
Texas Instruments (TI) is a global semiconductor company headquartered in Dallas, Texas. TI designs and manufactures analog and embedded processing chips used in industrial, automotive, consumer, communications, and enterprise systems.
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