25
LTC1293/LTC1294/LTC1296
129346fs
Unipolar conversion is requested and the data is output
MSB first. CS is driven at 1/64 the clock rate by the CD4520
and D
OUT
outputs the data. The output data from the D
OUT
pin can be viewed on an oscilloscope that is set up to
trigger on the falling edge of CS (Figure 24).
VERTICAL: 5V/DIV
HORIZONTAL: 2µs/DIV
CLK
FILLS
ZEROES
LSB
(B0)
NULL
BIT
MSB
(B11)
Figure 24. Scope Trace of the
LTC1294/6 “Quick Look” Circuit
Showing A/D Output
101010101010 (AAA
HEX
)
LTC1293 TA03
1k
22µF
TANTALUM
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
DGND
DV
CC
AV
CC
CLK
CS
D
OUT
D
IN
REF
+
REF
–
AGND
V
–
LTC1294
–
+
TO/FROM
68HC11
PROCESSOR
+15V
A2
LT1006
30.1k**
1µF
3.92M**
500k
ZERO°C TRIM
+15V
–
+
A1
LT1101
A=10
+15V
5V
OUT
10µF
500k
400°C TRIM
12.5k*
12k*
1k*
+
Rplat.
* TRW-IRC MAR-6 RESISTOR – 0.1%
** 1% FILM RESISTOR
Rplat. = 1kΩ AT 0°C – ROSEMOUNT #118MF
LT1027
Digitally Linearized Platinum RTD Signal Conditioner
TO
OSCILLOSCOPE
LTC1293 F23
CLK
EN
Q1
Q2
Q3
Q4
RESET
V
SS
V
DD
RESET
Q4
Q3
Q2
Q1
EN
CLK
V
IN
f/64
+5V
CLOCK IN
1MHz MAX
22µF
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
DGND
DV
CC
AV
CC
CLK
CS
D
OUT
D
IN
REF
+
REF
–
AGND
V
–
LTC1294
f
CD4520
Figure 23. “Quick Look” Circuit for the LTC1294/6
U
SA
O
PP
L
IC
AT
ITY
P
I
CA
L
A “Quick Look” Circuit for the LTC1294/6
Users can get a quick look at the function and timing of the
LTC1294/6 by using the following simple circuit (Figure
23). V
REF
is tied to V
CC
. D
IN
is tied high which means V
IN
should be applied to the CH7 with respect to COM. A
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
CS
D
OUT
