SN74HC95N 4-Bit Parallel-Access Shift Register IC
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What This Component Does
The SN74HC95N is a 4-bit shift register that can shift stored data either right or left, and also supports parallel (broadside) loading of 4 bits of data at once. This flexibility makes it useful for applications like serial-to-parallel data conversion, bidirectional data shifting, or as a building block in larger custom shift/counter circuits. It has parallel data inputs, parallel outputs, a mode control input to select shift direction, and two separate clock inputs (one used for parallel load / shift-left, the other for shift-right).
Core Operating Modes
| Mode | Condition | Behavior |
|---|---|---|
| Parallel Load | Mode control = HIGH | 4-bit data loaded on high-to-low transition of Clock 2 |
| Shift Right (QA→QD) | Mode control = LOW | Shifts on high-to-low transition of Clock 1 |
| Shift Left (QD→QA) | Mode control = HIGH, outputs externally connected QD→C, etc. | Shifts on high-to-low transition of Clock 2, serial data entered at input D |
Core Electrical Ratings
| Parameter | Symbol | Rating |
|---|---|---|
| Supply Voltage Range | VCC | 2.0V to 6.0V |
| Number of Bits | — | 4-bit |
| Logic Family | — | High-Speed CMOS (HC) |
| Max Clock Frequency (typ.) | fmax | ~ MHz range (CMOS HC-series typical) |
| Propagation Delay | tPD | Device/family dependent (see datasheet) |
| ESD Protection | — | Standard HC-series ESD protection |
| Operating Temperature Range | — | -40°C to +85°C (commercial HC-series typical) |
| Package | — | 14-Pin PDIP |
Important Usage Notes
- CMOS input handling: As with all CMOS logic devices, unused inputs must never be left floating — tie them to VCC or GND as appropriate. Floating inputs on CMOS ICs can cause unpredictable switching, excess current draw, or even latch-up damage.
- Mode control wiring matters: Since this device shares one control line for switching between parallel-load and shift-left modes (based on the state of clock/mode input combinations), double-check the wiring against the datasheet function table when integrating into a new design — incorrect mode control wiring is a common source of "stuck" or unexpected output behavior.
- Shift-left requires external wiring: Unlike some other shift register variants, shift-left operation on this device requires the user to externally connect each output back to the next stage's input (QD to input C, etc.) — this is not done internally, so verify these jumper connections if left-shift mode isn't working as expected.
- Legacy/obsolete part status: Several manufacturers have marked variants of the 74x95 family (including some HC95 variants) as obsolete or NRND (Not Recommended for New Designs). If sourcing a replacement, verify continued availability or consider a modern shift-register alternative (e.g., 74HC595 series) if the specific bidirectional shift-left/right functionality isn't strictly required.
- Voltage compatibility: The HC-series family operates from 2V–6V but is not inherently TTL-input-threshold compatible; if interfacing directly with 5V TTL logic outputs, verify voltage threshold compatibility or consider an HCT-series equivalent instead.
Typical Applications
Serial-to-parallel or parallel-to-serial data conversion, bidirectional data shifting circuits, LED/display driving via shift-based data loading, and general-purpose digital logic requiring temporary bit storage with shift capability.
Package Includes:
- 1 x SN74HC95N 4-Bit Parallel-Access Shift Register (14-Pin PDIP)