LTC1272-3ACS View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1272-3ACS' PDF : 20 Pages View PDF
LTC1272
APPLICATI S I FOR ATIO
Compatibility with the AD7572
Figure 21 shows the simple, single 5V configuration
recommended for new designs with the LTC1272. If an
AD7572 replacement or upgrade is desired, the LTC1272
can be plugged into an AD7572 socket with minor modi-
fications. It can be used as a replacement or to upgrade
with sample-and-hold, single supply operation and re-
duced power consumption.
The LTC1272, while consuming less power overall than
the AD7572, draws more current from the 5V supply (it
draws no power from the –15V supply). Also, a 1µs
minimum time between conversions must be provided to
allow the sample-and-hold to reacquire the analog input.
Figure 22 shows that if the clock is synchronous with CS
and RD, it is only necessary to short out the 10Ω series
resistor and reverse the polarity of the 10µF bypass
capacitor on the VREF pin. The –15V supply is not required
and can be removed, or, because there is no internal
connection to pin 23, it can remain unmodified. The clock
can be considered synchronous with CS and RD in cases
where the LTC1272 CLK IN signal is derived from the same
clock as the microprocessor reading the LTC1272.
2.42V
VREF
OUTPUT
ANALOG INPUT
(0V TO 5V)
+
0.1µF
10µF
8 OR 12-BIT
PARALLEL
BUS
*
LTC1272
A IN
VREF
AGND
VDD
NC
BUSY
D11 (MSB) CS
D10
RD
D9
HBEN
D8 CLK OUT
D7
CLK IN
D6
D0/8
D5
D1/9
D4
D2/10
DGND D3/11
+
10µ F
5V
0.1µF*
µP
CONTROL
LINES
* FOR GROUNDING AND BYPASSING HINTS
SEE FIGURE 11 AND APPLICATION HINTS
SECTION
LTC1272 • TA03
Figure 21. Single 5V Supply, 3µs, 12-Bit Sampling ADC
17
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