Part Number: 74LS259N, DM54LS259, DM74LS259

Function: 8-Bit Addressable Latches

Package: DIP 16 Pin Type

Manufacturer: Signetics, National ->Texas Instruments

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Description

74LS259N is an 8-bit addressable latch IC belonging to the TTL logic family, designed for general-purpose data storage, decoding, and demultiplexing functions. It allows individual control of each latch via address lines, making it highly versatile in digital systems requiring selective data storage or output control.

Features

• 8-bit addressable latch (individually selectable outputs)
• Serial data input with parallel outputs
• Performs serial-to-parallel data storage
• Active-high outputs
• Built-in 1-of-8 decoder / demultiplexer functionality
• Asynchronous clear (reset all outputs)
• Enable/disable input for easy expansion
• TTL-compatible logic levels (LS family)
• Direct replacement for Fairchild 9334

Pinout

Key Electrical Characteristics (Typical)

• Supply voltage (V_CC): 5V (TTL standard)
• Low power consumption (LS series)
• Fast switching speed compared to standard TTL

Design Notes

• Ensure proper timing between address and data signals for reliable latching
• Use decoupling capacitor (0.1µF) near VCC pin
• Fan-out capability typical of LS TTL (consider buffering if needed)
• Asynchronous clear is dominant → handle carefully in system reset design
• Useful for expanding I/O lines in microcontroller-based systems

How to Choose This IC

• Use when individual bit-level control is required via address lines
• Suitable for simple memory or control latch applications
• Prefer CMOS alternatives (e.g., 74HC259) for lower power designs
• Ensure compatibility with 5V TTL logic systems

Typical Applications

• Digital storage registers
• LED or relay control (individual bit control)
• Addressable output expansion
• Demultiplexing signals
• Control logic in embedded systems

Alternative / Equivalent Products

• 74HC259 (CMOS low-power version)
• CD4099 (CMOS addressable latch)
• 74LS373 (octal latch, non-addressable alternative)
• 74HC138 (decoder-only alternative)

 

Acquired by Texas Instruments on September 23rd, 2011.

Other data sheets are available within the file:

54LS259E, 54LS259J, 54LS259W, 74LS259M, 74LS259

74LS259N Datasheet PDF Download

Part Number: 2N3958

Function: N-Channel dual silicon junction field-effect transistor

Package: TO-71 Type

Manufacturer: Vishay Semiconductors

Image and Pinouts:

Description

2N3958 is a monolithic dual N-channel JFET optimized for precision differential amplification. The two JFETs are fabricated on the same die, ensuring excellent matching characteristics, which is critical for low-offset, low-drift analog front-end designs.

Core Characteristics

• Device type: Dual N-channel JFET (matched pair)
• Monolithic construction → superior thermal tracking
• Designed for differential input stages
• Ultra-low gate leakage current
• Low noise and high dynamic range

Functional Description

• Contains two closely matched JFETs sharing the same substrate
• Typically used as a differential pair in analog circuits
• Provides high input impedance with minimal bias current
• Ensures stable operation over temperature due to matched thermal behavior

Why Dual Matched JFET Matters

• Minimizes offset voltage in differential amplifiers
• Improves gain symmetry and linearity
• Reduces need for trimming in precision circuits
• Enhances CMRR and PSRR in op-amp front ends

Design Insights

• Best used in long-tailed pair configurations
• Requires proper biasing (constant current source recommended)
• Thermal coupling improves matching → avoid asymmetric PCB layout
• Shield high impedance nodes to reduce noise pickup
• Gate protection may be needed in high-voltage environments

Typical Circuit Role

• Input stage of precision operational amplifiers
• Instrumentation amplifiers
• Low-noise preamplifiers (sensor interfaces)
• Sample-and-hold circuits
• Analog computation and filtering circuits

Typical Differential Pair Topology

• Sources connected together → constant current source
• Drains connected to load resistors or active loads
• Gates serve as differential inputs (Vin+ / Vin−)

Performance Advantages

• Very high input impedance → negligible loading
• Low noise floor → suitable for microvolt-level signals
• Excellent matching → minimizes offset and drift
• Wide dynamic range → handles both small and large signals accurately

Limitations

• Lower transconductance compared to bipolar input stages
• Limited current drive capability
• Requires careful bias design for optimal linearity

Equivalent / Alternative Devices

• LSK389 (modern low-noise dual JFET)
• MAT02 / MAT12 (precision matched transistor pairs, BJT alternative)
• 2N3954 / 2N3956 (same family variants)
• BF862 (single low-noise JFET alternative)

2N3958 Datasheet PDF Download