特性 Features

? Buffered Inputs

? Four Operating Modes: Shift Left, Shift Right, Load

and Store

? Can be Cascaded for N-Bit Word Lengths

? I/O0 - I/O7 Bus Drive Capability and Three-State for

Bus Oriented Applications

? Typical fMAX = 50MHz at VCC = 5V, CL = 15pF, TA = 25oC

? Fanout (Over Temperature Range)

- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads

- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads

? Wide Operating Temperature Range . . . -55oC to 125oC

? Balanced Propagation Delay and Transition Times

? Significant Power Reduction Compared to LSTTL

Logic ICs

? HC Types

- 2V to 6V Operation

- High Noise Immunity: NIL = 30%, NIH = 30% of VCC

at VCC = 5V

? HCT Types

- 4.5V to 5.5V Operation

- Direct LSTTL Input Logic Compatibility,

VIL= 0.8V (Max), VIH = 2V (Min)

- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

描述 Description

The ’HC259 and ’HCT299 are 8-bit shift/storage registers

with three-state bus interface capability. The register has four

synchronous-operating modes controlled by the two select

inputs as shown in the mode select (S0, S1) table. The mode

select, the serial data (DS0, DS7) and the parallel data (I/O0

- I/O7) respond only to the low-to-high transition of the clock

(CP) pulse. S0, S1 and data inputs must be stable one setup

time prior to the clock positive transition.

The Master Reset (MR) is an asynchronous active low input.

When MR output is low, the register is cleared regardless of

the status of all other inputs. The register can be expanded

by cascading same units by tying the serial output (Q0) to

the serial data (DS7) input of the preceding register, and

tying the serial output (Q7) to the serial data (DS0) input of

the following register. Recirculating the (n x 8) bits is

accomplished by tying the Q7 of the last stage to the DS0 of

the first stage.

The three-state input/output I(/O) port has three modes of

operation:

1. Both output enable (OE1 and OE2) inputs are low and S0

or S1 or both are low, the data in the register is presented

at the eight outputs.

2. When both S0 and S1 are high, I/O terminals are in the

high impedance state but being input ports, ready for parallel

data to be loaded into eight registers with one clock

transition regardless of the status of OE1 and OE2.

3. Either one of the two output enable inputs being high will

force I/O terminals to be in the off-state. It is noted that

each I/O terminal is a three-state output and a CMOS

buffer input.