LTC1272_15 Datasheet, PDF (1/22 Pages) Linear Technology – 12-Bit, 3s, 250kHz Sampling A/D Converter

FEATURES
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}
APPLICATIONS
n _{High Speed Data Acquisition}
n _{Digital Signal Processing (DSP)}
n _{Multiplexed Data Acquisition Systems}
n _{Single Supply Systems}
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.
LTC1272
12-Bit, 3µs, 250kHz
Sampling A/D Converter
DESCRIPTION
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
(Pin 23, 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.
TYPICAL APPLICATION
2.42V
V_REF
OUTPUT
Single 5V Supply, 3µs, 12-Bit Sampling ADC
LTC1272
5V
ANALOG INPUT
(0V TO 5V)
+
0.1µF
10µF
A _IN
V_REF
AGND
V_DD
NC
BUSY
+
10µF
0.1µF
D11 (MSB) CS
D10
RD
D9
HBEN
µP
CONTROL
LINES
D8 CLK OUT
D7
CLK IN
8 OR 12-BIT
PARALLEL
BUS
D6
D0/8
D5
D1/9
D4
D2/10
DGND D3/11
0
–20
–40
–60
–80
–100
–120
–140
0
1024 Point FFT, f_S = 250kHz, f_IN = 10kHz
S
(N+D)
=
72.1
20
40
60
80
100
120
FREQUENCY (kHz)
LTC1272 • F02
LTC1272 • F01
For more information www.linear.com/1272
1272fc
1