Description:
The SN74HC75N contains four independent bistable (transparent) latches, commonly used for temporarily storing binary data between processing stages, such as between a microcontroller/CPU and an input/output or display device. Two latches are controlled together by one of two active-HIGH enable inputs (LE12 and LE34). While the enable (LE) input is HIGH, data present at the D input passes straight through to the Q output — the latch is "transparent." When the enable input goes LOW, the last data value present just before the transition is captured and held stable at the output, regardless of further changes on the D input, until the enable goes HIGH again.
Core Electrical Ratings:
| Parameter | Symbol | Rating |
|---|---|---|
| Supply Voltage Range | VCC | 2.0V to 6.0V |
| Number of Latches | — | 4 (Quad) |
| Logic Family | — | High-Speed CMOS (HC) |
| Propagation Delay (typ., CL=15pF, VCC=5V) | tPHL/tPLH | ~11ns |
| Input Capacitance | CI | ~3.5pF |
| Output Type | — | Complementary (Q and Q̄) |
| ESD Protection (HBM) | — | >2000V |
| ESD Protection (Machine Model) | — | >200V |
| Operating Temperature Range | — | -40°C to +125°C (typical for HC series) |
| Package | — | 16-Pin PDIP |
Pin Function Overview:
- nD (Data Inputs): Data to be latched
- LE12 / LE34 (Latch Enable): Controls whether latches 1&2 / 3&4 are transparent (HIGH) or holding (LOW)
- nQ / nQ̄ (Outputs): Complementary latched outputs
- VCC / GND: Located on the center pins of the package (note: this differs from many standard 74-series ICs where power pins are at the corners — always double-check pinout before wiring)
Important Usage Notes:
- CMOS input handling: As a CMOS device, unused inputs should never be left floating — tie them to VCC or GND as appropriate, since floating CMOS inputs can cause unpredictable output states, excess power consumption, or latch-up.
- Center-pin power arrangement: Unlike many standard logic ICs with power at the corner pins, this device has VCC and GND on the center pins — a common wiring mistake when swapping this part into a board designed for a different pin arrangement.
- Voltage compatibility: The HC-series logic family operates from 2V to 6V and is generally NOT directly TTL-output compatible at the input threshold level without care — if this is being used in a mixed TTL/CMOS system, verify voltage threshold compatibility (HCT-series is typically used instead for that purpose).
- Note on part status: This particular device (SN74HC75N in PDIP package) has been marked "Obsolete" by some distributors, meaning it may be increasingly difficult to source directly from TI; functionally equivalent alternatives from Nexperia (74HC75) or other manufacturers in the same package are generally drop-in compatible — verify datasheet timing specs match your application's requirements.
Typical Applications:
Data storage/buffering between digital logic stages, microprocessor/microcontroller interfacing, temporary storage for binary information between input/output devices, and general digital logic latch requirements in TTL/CMOS mixed-logic systems.
Package Includes:
- 1 x SN74HC75N Quad Bistable Latch IC (16-Pin PDIP)
