7 Detailed Description

7.1 Overview

Logic Diagram (Positive Logic) for the SN74HCS596 describes the SN74AC596-Q1, an 8-bit shift register that

feeds an 8-bit D-type storage register. Both the shift register clock (SRCLK) and storage register clock (RCLK)

are positive-edge triggered. If both clocks are connected together, the shift register always is one clock pulse

ahead of the storage register. Outputs QA through QH are controlled by the output enable (OE) input and have

open-drain outputs. The serial output QH’ is always active and has a push-pull output architecture.

7.2 Functional Block Diagram

RCLK

OE

SRCLR

SRCLK

SER

13

12

10

11

14

D

R

15

1

Q

A

Q

B

Q

C

Q

D

R

Q

D

Q

D

Q

2

Q

D

3

Q

E

4

Q

F

5

Q

G

6

D

R

7

9

Q

H’

Q

D

Q

Q

H

Figure 7-1. Logic Diagram (Positive Logic) for SN74AC596-Q1

7.3 Feature Description

7.3.1 Balanced CMOS Push-Pull Outputs

This device includes balanced CMOS push-pull outputs. The term balanced indicates that the device can sink

and source similar currents. The drive capability of this device may create fast edges into light loads, so routing

and load conditions should be considered to prevent ringing. Additionally, the outputs of this device are capable

of driving larger currents than the device can sustain without being damaged. It is important to limit the output

power of the device to avoid damage due to overcurrent. The electrical and thermal limits defined in the Absolute

Maximum Ratings must be followed at all times.

Unused push-pull CMOS outputs must be left disconnected.

7.3.2 Open-Drain CMOS Outputs

This device includes open-drain CMOS outputs. Open-drain outputs can only drive the output low. When in

the high logical state, open-drain outputs will be in a high-impedance state. The drive capability of this device

may create fast edges into light loads, so routing and load conditions should be considered to prevent ringing.

Additionally, the outputs of this device are capable of driving larger currents than the device can sustain without

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