LTC1272_1 Datasheet, PDF (1/20 Pages) Linear Technology – 12-Bit, 3μs, 250kHz Sampling A/D Converter

FEATURES
■ _{AD7572 Pinout}
■ _{12-Bit Resolution}
■ _{3µs and 8µs Conversion Times}
■ _{On-Chip Sample-and-Hold}
■ _{Up to 250kHz Sample Rates}
■ _{5V Single Supply Operation}
■ _{No Negative Supply Required}
■ _{On-Chip 25ppm/°C Reference}
■ _{75mW (Typ) Power Consumption}
■ _{24-Pin Narrow DIP and SOL Packages}
■ _{ESD Protected on All Pins}
U
APPLICATIO S
■ _{High Speed Data Acquisition}
■ _{Digital Signal Processing (DSP)}
■ _{Multiplexed Data Acquisition Systems}
■ _{Single Supply Systems}
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
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
DESCRIPTIO
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^TM 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 connected
on the LTC1272). The LTC1272 has the same 0V to 5V input
range as the AD7572 but, to achieve single supply opera-
tion, 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 APPLICATIO
Single 5V Supply, 3µs, 12-Bit Sampling ADC
2.42V
V_REF
OUTPUT
ANALOG INPUT
(0V TO 5V)
+
0.1µF
10µF
LTC1272
A _IN
V_REF
AGND
V_DD
NC
BUSY
+
10µ F
5V
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
LTC1272 • TA01
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 • TA02
1272fb
1