74LS Logic ICs, Bus Transceivers and Assortment Kits

74LS logic: select the actual device, not just the series number

This collection brings together 74LS-family logic ICs, DIP and surface-mount variants, assorted IC kits, and several multi-model listings that also offer 74HC, 74HCT and unrelated electronic components. The two digits after 74LS identify a function, not merely a size. A 74LS00 NAND gate, 74LS245 bus transceiver, 74LS373 transparent latch and 74LS283 adder cannot be substituted for one another. Many listings place several codes in one title but supply only the selected Color/model at the selected count. A genuine assortment kit is a separate offer whose component breakdown must be checked on its own product page.

What “LS” means for an engineering design

The 74LS family is low-power Schottky TTL logic. It is not synonymous with 74HC CMOS, 74HCT CMOS or the older unsuffixed 74-series families. A familiar Boolean function may be shared, but recommended supply, input HIGH/LOW thresholds, output drive and sink capability, loading, propagation delay, fan-out and temperature grade depend on the complete manufacturer part number. A 74HC replacement can fail at an LS output HIGH level unless the receiver's specified input thresholds are satisfied; an HCT input may be intended for TTL-compatible levels but still requires verification of supply, pinout and timing. Never design from an absolute-maximum rating, a generic “standard” supplier specification, or a series-wide claim. Consult the exact device datasheet at your supply, load and ambient temperature.

Package suffixes matter. Many options are DIP-14, DIP-16 or DIP-20 through-hole ICs, whereas SN74LS00DR, SN74LS245DWR, SN74LS245NSR and DM74LS245WM titles describe surface-mount packages. Check manufacturer package dimensions, lead pitch, body width, pin one and tape/reel suffixes; “SOP-20” or “DIP” alone does not define a drop-in PCB footprint or authentic manufacturer. The listing “Power Relay” for DM74LS245WM and “Protective case” for SN74LS245N do not redefine these devices as relays or a case; inspect the actual selected part and stated contents.

Basic gates, inverters and output topology

74LS00 is quad two-input NAND, 74LS02 quad two-input NOR, 74LS04 a hex inverter, 74LS08 quad two-input AND and 74LS32 quad two-input OR. 74LS86 is quad two-input XOR; 74LS10 and 74LS20 provide NAND configurations with different input counts, while 74LS30 and 74LS133 are wider-input NAND types. 74LS14 is a Schmitt-trigger inverter; its thresholds and hysteresis should be verified for the chosen supplier and operating conditions. Lists containing 74LS03, 74LS05, 74LS06, 74LS07, 74LS12, 74LS33 and 74LS38 require particular attention to open-collector or otherwise nonstandard output behavior and gate function. An open-collector output needs an appropriately designed pull-up and cannot be treated as an ordinary push-pull HIGH driver. Use the exact manufacturer's truth table and output circuit, particularly where a seller's “grid/inverter” or “positive NAND” headline is ambiguous.

Some multi-model gate products put 74LS00N DIP-14, 74LS02N, 74LS04N, 74LS08N, 74LS32N and many other LS codes under one Color menu. These are alternative selected chips, not a guarantee of one mixed bag. A heading saying every option is “DIP-14” is not reliable when options include 74LS245 and 74LS273, which are listed elsewhere as DIP-20. Verify each selected package separately. Other multi-model offers list 74HC00N, 74HC02N, 74HC04N, 74HC08N, 74HC14N, 74HC32N and 74HC164/165 beside SN74LS86N and SN74LS245N. Only a chosen LS code is an LS-family device.

Bus transceivers and buffers: direction, enable and pinout

The most repeated single-function product here is 74LS245, offered as SN74LS245N/HD74LS245P in DIP-20, and SN74LS245DWR/DM74LS245WM or SN74LS245NSR in surface-mount forms. This is an octal bidirectional bus transceiver with direction and output-enable control; it is not an isolated voltage level shifter, universal motor driver or power relay. Specify which side drives which side, whether the enable is asserted, and the receiving logic thresholds before use. Avoid simultaneous external drivers fighting on a bus. Check output current limits and bus loading for the manufacturer's particular device, and compare package pinouts before replacing a DIP board part with an SMD code.

SN74LS244N is an octal non-inverting three-state buffer/line driver; SN74LS240N is an inverting buffer family, and SN74LS241N has its own enable arrangement. SN74LS541N and SN74HCT541N may appear in a shared selector but belong to different logic families. SN74HCT245N and SN74HCT244N selections are HCT rather than LS; verify enable polarity, direction, pinout, loading and logic thresholds instead of assuming suffixes are cosmetic. The 74LS688 selection is a comparator, not a transceiver. A 74LS573 option, where offered in a multi-code menu, is a latch and must not be relabeled 74LS245.

Latches, flip-flops and shift registers

SN74LS373N is an octal transparent D latch with three-state outputs. SN74LS374N is an octal edge-triggered D flip-flop with three-state outputs; SN74LS273N is an octal D flip-flop with clear/reset behavior, while SN74LS377N has a clock-enable function. Latch transparency, output enable, clock enable and asynchronous clear are different electrical controls. SN74LS74AN/SN74LS74N/LS74ADR describe dual D flip-flops, and 74LS76/74LS112 options are JK-family flip-flop selections; check triggering, preset/clear polarity and device-specific timing rather than treating all flip-flops as the same. SN74LS175N and SN74LS174N offer other multi-bit D-type configurations. A misleading title that calls all DIP-20 choices a “74LS245” should not obscure the function of the actually selected variant.

74LS164 and 74LS165 denote different shift-register structures and signal directions; 74LS194 and 74LS299 have further mode and control distinctions. The LS595 option in a broad menu should be checked against the exact manufacturer's part code rather than inferred from a familiar HC595 shift-register listing. SN74HC595N and SN74HC595D in the same collection are HC-family serial-to-parallel shift-register choices, not LS245 equivalents. For clocked devices, validate clock edge, setup/hold time, propagation delay, output loading, initialization and mode controls from the actual manufacturer's truth table.

Counters, decoders, multiplexers and arithmetic

74LS90, 74LS92, 74LS93, 74LS160, 74LS161, 74LS163, 74LS190, 74LS191, 74LS192, 74LS193 and 74LS196 options are various counter/divider families, not one interchangeable “counter chip.” Review synchronous versus asynchronous behavior, up/down capability, preset, reset, output encoding and clock limits. SN74LS390N is another divider/counter choice found in a mixed-model listing. 74LS138/139 are decoder/demultiplexer choices, while 74LS147/148/145 are encoder or decoder types with device-specific output polarities; 74LS47, 74LS48, 74LS247 and 74LS248 are display-decoding/driver choices that require the correct display type and external drive design. Do not infer a universal common-anode/common-cathode compatibility from a shared 74LS prefix.

SN74LS151N, 74LS153, 74LS157 and 74LS253 are multiplexer/selector options with different channel structure and enable/output behavior. HD74LS283P/74LS283 is a four-bit binary full-adder type, not a general analog amplifier; 74LS85 is a magnitude comparator. SN74LS260N, 74LS133N and other wide-input logic products require exact truth-table and package checks. A seller's shorthand “logic IC” cannot tell you if a part stores state, selects an input, drives a bus or decodes a number.

Actual kits versus single-model choices

Some product titles explicitly offer 25-, 40- or 50-piece combination boxes or “20 values” 74-series kits, with examples such as 74LS00/02/04/08/32/47/86/90/138/245 or 74LS160/161/164/175/192/194/244/245/247/273. Those are presented as assortments, but the actual number of each code, whether IC sockets are included, and whether the kit is LS-only, HC-only or mixed must be checked in that listing's packing detail. A 50PCS kit and a separate listing with Color “50 pcs 74LS” are not automatically the same contents. Other kit menus offer 74LS00–74LS48, 74LS73–74LS151 and 74LS160–74LS273 as separate alternatives; the displayed range names do not prove every integer part code in the interval is present. “100pcs IC Sockets” and “115pcs IC Sockets” options are socket assortments, not a box of LS chips.

Conversely a title such as “10PCS SN74LS245N SN74LS373N SN74LS244N SN74LS273N SN74LS374N” with a Color selector normally identifies one model at the stated count. A Color entry “20PCS SN74LS190N” is a 20-piece choice of that model, while “5PCS L293D” is a different selected part. A field labeled Voltage may actually distinguish 10pcs from 20pcs; read its value as an order option, not an electrical voltage rating. Default Title is not itself evidence of a mixed bundle, independent testing or a particular chip manufacturer.

Cross-listed parts are not 74LS logic

Multi-code offerings here can also select LM7805 or LM78L15 regulators, DRV8833 or L293D motor drivers, MAX485 or MCP2551 communications transceivers, STM32/NUC/ATtiny/PIC microcontrollers, audio ICs, switching power controllers, memory ICs, RF devices, transistors, bridge rectifiers, analog amplifiers and sensors. Examples include CS8406-CZZ, TCA4500A, F71808EU, SX1276IMLTRT, 24FC1025, PCF8563T, TC58BVG0S3HTA00, TMP75AIDR, AT25SF081 and IRLB3034PBF, each requiring its own interface and package checks. A same-title option for SN74LS138N or SN74LS245N does not convert the other listed codes into 74LS logic. A heading saying “Power module” or “Motor Driver IC” likewise does not change a selected SN74LS245N into a motor driver. No cross-listed item has been removed or recategorized.

Practical ordering and compatibility checklist

1. State the function: Boolean gate, buffer/transceiver, latch, flip-flop, counter, decoder, multiplexer, shift register, display driver or kit. Identify the exact truth table and required control pins.
2. Read the selected full code: Color and Model Number can carry the model, packaging and quantity; do not use a long headline as the ordered bill of materials.
3. Match the family: LS TTL, HC CMOS, HCT CMOS and unsuffixed 74 codes need separate VIH/VIL, VOH/VOL, supply, drive and timing checks. There is no blanket pin-compatible or electrical replacement guarantee.
4. Match package and pinout: check DIP versus SMD, pin count, pitch, dimensions, pin-one orientation, socket fit and manufacturer's suffix. Common root codes alone do not validate a footprint.
5. Design for the system: consider pull-ups on open-collector outputs, bus contention, three-state enables, clock margins, loading, decoupling and defined unused inputs in accordance with the exact datasheet. Do not connect a logic IC directly to mains or unknown high-energy circuits.
6. Validate the shipment: distinguish one-model 1/5/10/20/30/50/100-piece orders from actual mixed kits; confirm the selected kit breakdown and accessories. “New original” and generic supplier test claims are not independent provenance or certification evidence.

Frequently asked questions

Can 74HC245 replace 74LS245?

Not automatically. Although both names refer to octal bidirectional bus-transceiver families, input thresholds, supply requirements, drive, timing and package must be checked for the actual system. Confirm the complete manufacturer codes and all connected logic levels.

Is 74LS245 a voltage level shifter?

It is a bidirectional bus transceiver intended for its specified logic supply and signal levels. It is not a universal translator between arbitrary voltage rails, nor a relay or an isolated interface.

Does a product title containing ten LS part numbers include all ten?

Only when the specific product is an actual assortment with an explicit packing list. Where Color selects SN74LS245N, SN74LS373N or another code, it generally specifies one selected model; verify the final variant and count.

What is the difference between LS373 and LS374?

LS373 is a transparent latch family; LS374 is an edge-triggered flip-flop family. Both have multiple outputs, but their data-capture timing differs. Check enable polarity, output behavior and pin assignment before choosing.

Does a 50-piece kit include IC sockets?

Not necessarily. Some listings separately select socket kits or advertise sockets with specific assortment options. Confirm the exact chosen kit's packing details; do not infer accessory inclusion from the collection title.

Are the non-LS options errors?

They are separate selectable products visible in this mixed collection. They must be evaluated by their own code and specifications rather than described as 74LS ICs or silently removed.