SN74HC139NS Texas Instruments Integrated Circuit (Small Outline Packages) In Stock
The SN74HC139NS is a dual 2-to-4 line decoder and demultiplexer from Texas Instruments in a 16-pin SOP package, featuring active-low outputs, individual enable inputs per decoder section, and HC CMOS logic operating from 2 V to 6 V supply. It is used for address decoding, chip-select generation, and data routing in microprocessor, FPGA, and memory expansion circuits.
- Manufacturer
- Texas Instruments
- Package
- Small Outline Packages
- Pin Count
- 16
- Lifecycle
- ACTIVE
- Datasheet
- SN74HC139NS Datasheet PDF
- Category
- Integrated Circuit
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Dual independent 2-to-4 line decoder/demultiplexer
- Active-low outputs with individual enable per section
- HC CMOS: operates from 2 V to 6 V supply
- Propagation delay typically 7 ns at 5 V
- 16-pin SOP package for compact SMT assembly
- TTL-compatible input thresholds for mixed-logic designs
Applications
The SN74HC139NS is a standard component in microprocessor address decoding circuits where 2 select lines must activate one of 4 chip-enable signals for memory banks, peripheral registers, or I/O port expansion. It is also used in data demultiplexing stages on FPGA development boards and digital control panels to route control signals to one of 4 target subsystems based on a 2-bit address.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for SN74HC139NS:
Frequently Asked Questions
How does the enable pin on each section of the SN74HC139NS affect bus expansion designs?
Each of the 2 decoder sections in the SN74HC139NS has its own active-low enable input, so both halves can be independently gated off by asserting their respective enable high. This allows a single IC to act as an 8-output decoder when the enable of section B is driven by one of the active-low outputs of section A, cascading the two 2-to-4 decoders into a 3-to-8 configuration.
Over what supply voltage range does the SN74HC139NS operate and how does voltage affect speed?
The SN74HC139NS operates from 2 V to 6 V. At 2 V supply the propagation delay is approximately 27 ns, at 4.5 V it drops to roughly 8 ns, and at 6 V it falls below 7 ns. Designers targeting 50 MHz address decode cycles should use the 5 V or higher supply to ensure the 7 ns delay meets setup-time budgets for fast SRAM and CPLD chip-select inputs.
Can the SN74HC139NS decode a 3-bit address to 8 outputs using only a single IC?
Yes. By connecting address bit A2 to the enable of section B and its complement (or one of section A's 4 active-low outputs) to the enable of section A, both 2-to-4 sections together respond to a full 3-bit address, producing 8 mutually exclusive active-low chip-select outputs from 3 address lines and 1 chip within a 16-pin SOP package.
What output drive strength does the SN74HC139NS provide and what bus loads can it handle?
The SN74HC139NS HC CMOS outputs source and sink approximately 4 mA at 5 V supply into standard logic loads, sufficient to drive 10 or more LS-TTL inputs or a series of HC CMOS chip-enable pins with fanout up to 50 unit loads. Pull-up resistors of 4.7 kΩ or lower are recommended if the outputs must drive 3.3 V inputs from a 5 V supply rail.
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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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