Datasheet

21
LTC1292/LTC1297
12927fb
If V
CC
and V
REF
are not tied together, then V
CC
should
be turned on first, then V
REF
. If this sequence cannot be
met, connecting a diode from V
REF
to V
CC
is recom-
mended (see Figure 25).
Because a unique input protection structure is used on
the digital input pins, the signal levels on these pins can
exceed the device V
CC
without damaging the device.
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
Figure 26. “Quick Look” Circuit for the LTC1292
5V
LTC1292/7 F23
1N4148 DIODES
V
CC
CLK
D
OUT
V
REF
CS
+IN
–IN
GND
LTC1292
LTC1297
5V
LTC1292/7 F24
1N4148 DIODES
1k
V
CC
CLK
D
OUT
V
REF
CS
+IN
–IN
GND
LTC1292
LTC1297
Figure 24b. Overvoltage Protection with
Diode Clamps and Current Limiting Resistor
Figure 23. Overvoltage Protection with Clamp Diodes
5V
LTC1292/7 F25
1N4148
5V
V
CC
CLK
D
OUT
V
REF
CS
+IN
–IN
GND
LTC1292
LTC1297
Figure 25. Separate V
CC
and V
REF
Supplies
5V
LTC1292/7 F24a
250Ω
1k
V
CC
CLK
D
OUT
V
REF
CS
+IN
–IN
GND
LTC1292
LTC1297
Figure 24a. Overvoltage Protection with
Current Limiting Resistors
TO OSCILLOSCOPE
CD4520
LTC1292/7 F26
Q1
RESET
V
DD
EN
CLK
Q2
Q3
Q4
0.1µF
V
IN
f/32
+5V
CLOCK IN
1MHz
22µF
CLK
EN
Q2
Q3
Q4
V
SS
Q1
RESET
V
CC
CLK
D
OUT
V
REF
CS
+IN
–IN
GND
LTC1292