SN74LS156DE4 Texas Instruments Integrated Circuit (Small Outline Packages) In Stock
SN74LS156DE4 is a dual 2-line to 4-line decoder/demultiplexer from Texas Instruments, built on the LS (Low-power Schottky) TTL process. Each section decodes 2 binary address inputs into 4 mutually exclusive open-collector outputs with independent enable pins, enabling use as a 1-of-8 demultiplexer when both sections are combined. Housed in a 16-pin SOIC package, it suits address decoding, data routing, and bus expansion in digital logic systems.
- Manufacturer
- Texas Instruments
- Package
- Small Outline Packages
- Pin Count
- 16
- Lifecycle
- OBSOLETE
- Datasheet
- SN74LS156DE4 Datasheet PDF
- Category
- Integrated Circuit
- Temp Range
- ?°C to 70.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
What are the key features of SN74LS156DE4?
- Dual 2-to-4 decoder sections configurable as a single 1-of-8 demultiplexer
- Open-collector outputs allowing wire-AND connections and direct LED drive
- Independent active-low enable pin on each section for flexible gating
- LS TTL process with output sink current up to 8 mA for standard TTL loads
- Compatible with 5 V TTL and CMOS logic families
- 16-pin SOIC package widely available with broad distributor stock
What is SN74LS156DE4 used for?
The SN74LS156DE4 is used in digital systems for address decoding, where 2 binary address lines select one of 4 outputs to enable a specific memory bank or peripheral device. When both decoder sections are cascaded with a common address, it functions as a 1-of-8 demultiplexer suitable for data bus expansion and chip-select generation in microprocessor systems. Its open-collector outputs also make it practical for driving indicator LEDs or wired-OR logic networks in industrial control and test equipment.
What are the specifications of SN74LS156DE4?
| YTEOL | 0 |
| Additional Feature | USABLE AS 1 TO 8 DEMULTIPLEXER |
| Family | LS |
| Input Conditioning | STANDARD |
| JESD-30 Code | R-PDSO-G16 |
| JESD-609 Code | e4 |
| Load Capacitance (CL) | 15pF |
| Logic IC Type | 2-LINE TO 4-LINE DECODER |
| Max I(ol) | 0.008A |
| Number of Functions | 2 |
| Output Characteristics | OPEN-COLLECTOR |
| Output Polarity | INVERTED |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | SOP16,.25 |
| Package Shape | RECTANGULAR |
| Package Style | SMALL OUTLINE |
| Packing Method | TUBE |
| Peak Reflow Temperature (Cel) | 260 |
| Power Supply Current-Max (ICC) | 10mA |
| Prop. Delay@Nom-Sup | 51ns |
| Propagation Delay (tpd) | 51ns |
| Qualification Status | Not Qualified |
| Supply Voltage-Max (Vsup) | 5.25V |
| Supply Voltage-Min (Vsup) | 4.75V |
| Supply Voltage-Nom (Vsup) | 5V |
| Surface Mount | YES |
| Technology | TTL |
| Temperature Grade | COMMERCIAL |
| Terminal Finish | Nickel/Palladium/Gold (Ni/Pd/Au) |
| Terminal Form | GULL WING |
| Terminal Pitch | 1.27mm |
| Terminal Position | DUAL |
| Time@Peak Reflow Temperature-Max (s) | 30 |
| Package | Small Outline Packages |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| Moisture Sensitivity Level | MSL 1 |
| ECCN | EAR99 |
| HTS Code | 8542.39.00.60 |
Where can I find the SN74LS156DE4 datasheet?
SN74LS156DE4 Datasheet DownloadOfficial datasheet from Texas Instruments
What are equivalent replacements for SN74LS156DE4?
Compatible alternatives and drop-in replacements for SN74LS156DE4:
Texas Instruments LS Series, Inverted Output, TTL, PDSO16
Frequently Asked Questions
How can both sections of the SN74LS156DE4 be combined into a single 1-of-8 demultiplexer?
Both 2-to-4 decoder sections share the same 2 address inputs and can be enabled independently by their own active-low enable pins. By tying one section's enable to a logic 0 and the other's enable to the MSB address line, the 8 open-collector outputs together represent a full 1-of-8 decode. This allows selection of 8 distinct devices using only 3 address lines, with no external logic required.
What is the output sink current capability of the SN74LS156DE4, and can it directly drive indicator LEDs?
The SN74LS156DE4 open-collector outputs can sink up to 8 mA, which is sufficient to drive a standard indicator LED with an appropriate series resistor. For a 5 V supply and a red LED with a 2 V forward voltage, a 390 Ω series resistor limits current to approximately 7.7 mA, staying within the device's rated sink current and producing adequate brightness without an external driver transistor.
Which logic families is the SN74LS156DE4 compatible with, and does it work in 3.3 V systems?
The SN74LS156DE4 is a 5 V TTL device compatible with LS, S, and standard TTL families, as well as 5 V CMOS logic. It is not directly compatible with 3.3 V logic systems because its input threshold voltages require a minimum high-level input of 2 V, and its open-collector outputs pull to the VCC rail which must be 5 V. Level-shifting is required for interfacing with 3.3 V microcontrollers.
How does the enable pin on each section of the SN74LS156DE4 help in memory decode circuits?
Each section has an independent active-low enable input (G). When G is high, all 4 outputs of that section are forced high regardless of address inputs, effectively deselecting all devices on that bank. This allows address decoding logic to gate entire groups of 4 chip-select lines with a single control signal, simplifying bus arbitration in systems with multiple memory banks or peripheral segments at distinct address regions.
For a new design, should the SN74LS156DE4 be replaced with a newer CMOS equivalent like 74HC138?
The 74HC138 offers a 3-to-8 decoder in a 16-pin package with CMOS-compatible 2 V to 6 V supply, lower power consumption under 80 µA quiescent current versus the LS device at several milliamps, and push-pull outputs with higher drive current of 25 mA. For new designs requiring 3.3 V compatibility or battery operation, 74HC138 or 74LVC138 are preferred. The SN74LS156DE4 remains appropriate for legacy 5 V board repairs or open-collector wired-AND applications.
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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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