74273 Octal D-Type Flip-Flop with Clear Technical Summary

Overview

The 74273 is a high-speed octal D-type flip-flop integrated circuit featuring edge-triggered functionality and an asynchronous master reset. This component contains eight individual D-type flip-flops with a common clock and clear input, making it ideal for applications requiring synchronous data storage and transfer. The device operates with positive-edge triggered clocking and provides buffered outputs capable of driving low-impedance loads.

Constructed using advanced silicon-gate CMOS technology, the 74273 offers the low power consumption typical of CMOS circuits while maintaining high noise immunity and the ability to drive 15 LSTTL loads. The clear function is asynchronous and active-low, overriding both the clock and data inputs when asserted.

Features

• Eight edge-triggered D-type flip-flops with buffered outputs
• Common clock and asynchronous clear inputs
• Positive-edge clock triggering
• Asynchronous active-low clear (master reset)
• Output capability: standard
• ICC category: MSI
• High noise immunity: 0.45 VCC (typ.)
• Balanced propagation delays
• Wide operating voltage range: 2V to 6V
• Low power consumption: 80μA max. (at TA=25°C)
• Compatible with LSTTL outputs

Applications

The 74273 finds use in numerous digital system applications including:

• Buffer/storage registers
• Data synchronization circuits
• Temporary data storage in microprocessor systems
• Bus interface circuits
• Parallel data transfer systems
• State machine implementation
• Input/output port expansion
• Pipeline registers
• Data distribution networks

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (VCC): -0.5V to +7V
• DC Input Voltage (VI): -0.5V to VCC + 0.5V
• DC Output Voltage (VO): -0.5V to VCC + 0.5V
• DC Input Diode Current (IIK): ±20mA
• DC Output Diode Current (IOK): ±20mA
• DC Output Current (IO): ±25mA
• DC Supply Current per Output Pin (ICC or IGND): ±50mA
• Storage Temperature Range (TSTG): -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (VCC): 2V to 6V
• Input Voltage (VI): 0V to VCC
• Output Voltage (VO): 0V to VCC
• Operating Temperature Range (TA): -40°C to +85°C
• Input Rise/Fall Time (tr, tf): 0V to VCC, 1000ns max.

DC Characteristics

• High-Level Input Voltage (VIH): 0.7 VCC (min.)
• Low-Level Input Voltage (VIL): 0.3 VCC (max.)
• High-Level Output Voltage (VOH): VCC - 0.1V (min.) at IOH = -4mA
• Low-Level Output Voltage (VOL): 0.1V (max.) at IOL = 4mA
• Input Leakage Current (II): ±1μA (max.) at VCC = 6V
• Quiescent Supply Current (ICC): 80μA (max.) at VCC = 6V

AC Characteristics

• Propagation Delay Time (tPLH, tPHL): 15ns (typ.), 30ns (max.) at VCC = 4.5V
• Clock Pulse Width (tW): 10ns (min.) at VCC = 4.5V
• Setup Time (tSU): 20ns (min.) at VCC = 4.5V
• Hold Time (tH): 5ns (min.) at VCC = 4.5V
• Maximum Clock Frequency (fMAX): 35MHz (typ.) at VCC = 4.5V

Package Information

The 74273 is available in multiple package options:

• 20-pin DIP (Dual In-line Package): 0.3" width, through-hole mounting
• 20-pin SOIC (Small Outline IC): Surface mount package, 0.154" width
• 20-pin TSSOP (Thin Shrink Small Outline Package): Surface mount, 4.4mm width

Pin Configuration

• Pin 1: CLEAR (Master Reset Input, Active LOW)
• Pins 2,5,6,9,12,15,16,19: Q0 to Q7 (Flip-Flop Outputs)
• Pins 3,4,7,8,13,14,17,18: D0 to D7 (Data Inputs)
• Pin 11: CLOCK (Clock Input, LOW to HIGH Edge Triggered)
• Pin 10: GND (Ground, 0V)
• Pin 20: VCC (Positive Supply Voltage)

Functional Description

The 74273 octal D-type flip-flop features eight edge-triggered flip-flops with individual D inputs and Q outputs. The common clock (CP) input loads all flip-flops simultaneously on the low-to-high transition of the clock pulse. The asynchronous clear (CLR) input, when low, resets all outputs to low regardless of the state of other inputs.

Data at the D inputs meeting the setup time requirements is transferred to the Q outputs on the positive-going edge of the clock pulse. Clock triggering occurs at a voltage level and is not directly related to the rise time of the clock pulse. Following the hold-time interval, data at the D input may be changed without affecting the output levels.

Truth Table

• CLEAR = L, CLOCK = X, D = X: Q = L (Clear active)
• CLEAR = H, CLOCK = L to H, D = L: Q = L (Data transfer)
• CLEAR = H, CLOCK = L to H, D = H: Q = H (Data transfer)
• CLEAR = H, CLOCK = X (no edge), D = X: Q = Qn (No change)

Where: L = Low level, H = High level, X = Don't care, ↑ = Low-to-High transition, Qn = Previous output state

Handling and Storage

Standard CMOS handling precautions should be observed with the 74273:

• Protect against electrostatic discharge (ESD) during handling
• Store in anti-static packaging when not in use
• Avoid exposure to excessive moisture (follow MSL ratings)
• Use proper soldering techniques appropriate