LSI/CSI
UL
®
LS7166
(631) 271-0400 FAX (631) 271-0405
December 2002
LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747
A3800
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)
*
- See Fig. 1
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)
20-Pin Package PIN ASSIGNMENT - Top View
*
(Contact factory for 24-Pin TSSOP Package Pinout)
(Write Input) WR
(Chip Select Input) CS
(Load Counter/Load Latch) LCTR/LLTC
(A, B Gate/Reset Counter)ABGT/RCTR
V
DD
(+5V)
(Count Input) A
(Count Input) B
D0
D1
D2
1
2
3
20
19
18
V
SS
(GND)
RD (Read Input)
C/D (Control/ Data Input)
BW (Borrow Output)
CY (Carry Output)
D7
D6
D5
D4
D3
LSI
LS7166
FIGURE 1
4
5
6
7
8
9
10
17
16
15
14
13
12
11
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.
7166-120902-1
LSI [ LSI COMPUTER SYSTEMS ]
