Theory of Operation—2246 1Y and 2246 Mod A Service
Trigger Logic 1C (FLIC)
The Trigger Logic 1C or FLIC (fast-logic integrated
circuit, U602 Diagram 4) does most of the fast logic
functions required to run the oscilloscope. The func
tions are: A Sweep control, B Sweep control and
measurement gate generation, Z-Axis control, and
trigger status detection.
The A Sweep logic generates the A Sweep gate
signal (A GATE), and provides trigger status infor
mation about the state of the A Trigger. The B
Sweep logic interfaces to the Delay Time Com
parators (Diagram 3) and generates the B Sweep
gate (B GATE) and measurement gate signals.
There is also some logic that monitors the B Trigger
signal status when making voltage measurements
with the B Trigger circuit. The Z-Axis control logic
provides outputs for controlling the crt beam
intensity.
The Trigger Logic circuit is done in an ECL (em itter-
coupled logic) gate array, and all inputs and outputs
are compatible with standard ECL components.
Pin Description
The following is a description of the fast logic pin
outs (see Figure 3 -3 ).
BLANK:
Blanking input, from the Display
Logic 1C (U600).
HD1, HDO:
Horizontal display select inputs,
from the Display Logic 1C.
ZEN: Z-Axis enable input, from the Display
Logic 1C. Active low.
BUSY:
Counter busy signal. Not used in the
2246 1Y and 2246 Mod A.
ATRIG:
A Sweep trigger input.
EOAS:
End of A Sweep. This signal goes
high when the A Sweep ramp crosses its
end-of-sw eep threshold.
THO:
Trigger holdoff input from the Display
Logic 1C.
1
V ee
S IN
B L A N K
A1
HD1
AO
HD O
E OB S
ZE N
D L Y 1 2
40
2
39
3
38
4
37
5
^36
6_
^ 3 5
7
R
A T R I G
i
B T R I G
G
___
E O A S
g
MGE
E
T H O
R
DS
V
1
V
v cc
£
v cc
NC
G
TDO
I
D A T A
C
MS E L
v
(FLIC)
u
34
8
33
g
3 2
i °
_
31
n
30
12^
29
13_
28
14
v cco
v cco
A G A T E
C G A T E
NC
NC
V
V
vcco
vcco
27
15
26
16_
2 3
17
24
18
u 1
u u A I L
52
b
U
b
53
NC
54
v
23
19
22
2°
2
\
V EE
6081-06
Figure 3-3. Trigger Logic 1C (FLIC, U602)
pin-out diagram.
S IN
: Strobe input. Latches data into the in
ternal register. Active low.
A1, AO:
Address inputs. See Table 3-17 for
addressing codes.
EOBS:
End of B Sweep. This signal goes
high when the B Sweep ramp crosses its
end-of-sw eep threshold.
DLY12:
Input from first delay comparator.
The comparator for the delay input switches
from low to high after the end of either the
first or the second sweep delay.
3-26
Summary of Contents for 2246 1Y
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