24-BIT QUADRATURE COUNTER

FEATURES:

• Programmable modes are: Up/Down,

Binary, BCD, 24 Hour Clock, Divide-by-N,

x1 or x2 or x4 Quadrature and Single Cycle.

• DC to 20 MHz Count Frequency.

• 8-Bit I/O Bus for Microprocessor

Communication and Control.

• 24-Bit comparator for pre-set count

comparison.

• Readable status register.

• Input/Output TTL and CMOS compatible.

• 5 Volt operation (Vdd - Vss).

• LS7166 (DIP); LS7166-S (SOIC);

LS7166-TS24 (24-Pin TSSOP)

GENERAL DESCRIPTION:

The LS7166 is a CMOS, 24-bit counter that

can be programmed to operate in several dif-

ferent modes. The operating mode is set up

by writing control words into internal control

registers (see Figure 8). There are three 6-bit

and one 2-bit control registers for setting up

the circuit functional characteristics.

In addi-

tion to the control registers, there is a 5-bit out-

put status register (OSR) that indicates the cur-

rent counter status. The IC communicates with

external circuits through an 8-bit three state I/O

bus. Control and data words are written into

the LS7166 through the bus. In addition to the

I/O bus, there are a number of discrete inputs

and outputs to facilitate instantaneous hard-

ware

based

control

functions

and

in-

stantaneous status indication.

REGISTER DESCRIPTION:

Internal hardware registers are accessible

through the I/O bus (D0 - D7) for READ or

WRITE when CS = 0. The C/D input selects

between the control registers (C/D = 1) and the

data registers (C/D = 0) during a READ or

WRITE operation. (See Table 1)

The information included herein is believed to be

accurate and reliable. However, LSI Computer Systems,

Inc. assumes no responsibilities for inaccuracies, nor for

any infringements of patent rights of others which may

result from its use.

(Write Input) WR

(Chip Select Input) CS

(Load Counter/Load Latch) LCTR/LLTC

(A, B Gate/Reset Counter)ABGT/RCTR

(Count Input) A

(Count Input) B

D0

D1

D2

RD (Read Input)

C/D (Control/ Data Input)

BW (Borrow Output)

CY (Carry Output)

D7

D6

D5

D4

D3

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

December 2002

FIGURE 1

7166-120902-1

LSI/CSI

LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747

(631) 271-0400 FAX (631) 271-0405

LS7166

UL

®

A3800

20-Pin Package PIN ASSIGNMENT - Top View