LTC1272
1
1272fc
For more information www.linear.com/1272
TYPICAL APPLICATION
DESCRIPTION
12-Bit, 3µs, 250kHz
Sampling A/D Converter
The LTC1272 is a 3µs, 12-bit, successive approximation
sampling A/D converter. It has the same pinout as the
industry standard AD7572 and offers faster conversion
time, on-chip sample-and-hold, and single supply opera-
tion. It uses LTBiCMOS™ switched-capacitor technology
to combine a high speed 12-bit ADC with a fast, accurate
sample-and-hold and a precision reference.
The LTC1272 operates with a single 5V supply but can
also accept the 5V/–15V supplies required by the AD7572
(Pin23, the negative supply pin of the AD7572, is not con-
nected on the LTC1272). The LTC1272 has the same 0V to
5V input range as the AD7572 but, to achieve single supply
operation, it provides a 2.42V reference output instead of
the –5.25V of the AD7572. It plugs in for the AD7572 if the
reference capacitor polarity is reversed and a 1µs sample-
and-hold acquisition time is allowed between conversions.
The output data can be read as a 12-bit word or as two
8-bit bytes. This allows easy interface to both 8-bit and
higher processors. The LTC1272 can be used with a crystal
or an external clock and comes in speed grades of 3ms
and 8ms.
Single 5V Supply, 3µs, 12-Bit Sampling ADC
FEATURES
APPLICATIONS
n
AD7572 Pinout
n
12-Bit Resolution
n
3µs and 8µs Conversion Times
n
On-Chip Sample-and-Hold
n
Up to 250kHz Sample Rates
n
5V Single Supply Operation
n
No Negative Supply Required
n
On-Chip 25ppm/°C Reference
n
75mW (Typ) Power Consumption
n
ESD Protected on All Pins
n
24-Pin Narrow DIP and SOL Packages
n
High Speed Data Acquisition
n
Digital Signal Processing (DSP)
n
Multiplexed Data Acquisition Systems
n
Single Supply Systems
1024 Point FFT, f
S
= 250kHz, f
IN
= 10kHz
10µF
IN
REF
D11 (MSB)
D10
D9
D8
D7
CLK IN
CLK OUT
HBEN
RD
CS
BUSY
NC
V
LTC1272
D6
D5
D4
DGND
D3/11
D2/10
D1/9
D0/8
A
V
AGND
DD
µP
CONTROL
LINES
0.1µF
5V
8 OR 12-BIT
PARALLEL
BUS
ANALOG INPUT
(0V TO 5V)
10µF
0.1µF
LTC1272 • F01
+
+
2.42V
V
OUTPUT
REF
FREQUENCY (kHz)
0
–140
AMPLITUDE (dB)
20 40 60 80
LTC1272 • F02
–120
–100
–80
–60
–40
–20
0
100 120
S
(N+D)
= 72.1
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
LTBiCMOS is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
