LTC1274 Datasheet, PDF (1/20 Pages) Linear Technology – 12-Bit, 10mW, 100ksps ADCs with 1uA Shutdown

LTC1274/LTC1277
12-Bit, 10mW, 100ksps
ADCs with 1µA Shutdown
FEATURES
s _{Low Power Dissipation: 10mW}
s _{Sample Rate: 100ksps}
s _{Samples Inputs Beyond Nyquist, 72dB S/(N + D)}
and 82dB THD at f_IN = 100kHz
s _{Single Supply 5V or ±5V Operation}
s _{Power Shutdown to 1µA in Sleep Mode}
s _{180µA Nap Mode (LTC1277) with Instant Wake-Up}
s _{Internal Reference Can Be Overdriven}
s _{Internal Synchronized Clock}
s _{0V to 4.096V or ±2.048V Input Ranges (1mV/LSB)}
s _{24-Lead SO Package}
APPLICATI S
s _{Battery-Powered Portable Systems}
s _{High Speed Data Acquisition for PCs}
s _{Digital Signal Processing}
s _{Multiplexed Data Acquisition Systems}
s _{Audio and Telecom Processing}
s _{Spectrum Analysis}
DESCRIPTIO
The LTC^®1274/LTC1277 are 8µs sampling 12-bit A/D
converters which draw only 2mA (typ) from single 5V or
±5V supplies. These easy-to-use devices come complete
with a 2µs sample-and-hold, a precision reference and an
internally trimmed clock. Unipolar and bipolar conversion
modes add to the flexibility of the ADCs.
Two power-down modes are available in the LTC1277. In
Nap mode, the LTC1277 draws only 180µA and the instant
wake-up from Nap mode allows the LTC1277 to be pow-
ered down even during brief inactive periods. In Sleep
mode only 1µA will be drawn. A REFRDY signal is used to
show the ADC is ready to sample after waking up from
Sleep mode. The LTC1274 also provides the Sleep mode
and REFRDY signal.
The A/D converters convert 0V to 4.096V unipolar inputs
from a single 5V supply or ±2.048V bipolar inputs from
±5V supplies.
The LTC1274 has a single-ended input and a 12-bit
parallel data format. The LTC1277 offers a differential
input and a 2-byte read format. The bipolar mode is
formatted as 2’s complement for the LTC1274 and offset
binary for the LTC1277.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
Single 5V Supply, 10mW, 100kHz, 12-Bit ADC
LTC1277
2.42V
V_REF OUTPUT
ANALOG ¹
DIFFERENTIAL INPUTS 2
(0V TO 4.096V) ₃
+
4
10µF
0.1µF ₅
6
7
8
9
10
8-BIT 11
PARALLEL
BUS
12
A_IN+
A_IN–
V_REF
AGND
REFRDY
SLEEP
NAP
D7
D6
D5
D4
DGND
24
V_{DD 23}
V_{SS 22}
BUSY
21
CS
20
RD
19
CONVST
18
HBEN
17
V_{LOGIC 16}
D0/8
15
D1/9
14
D2/10
13
D3/11
+
10µF
µP
CONTROL
LINES
5V
0.1µF
OPTIONAL 3V SUPPLY
TO INTERFACE WITH 3V
PROCESSOR
LTC1274/77 • TA01
Supply Current vs Sample Rate with
Sleep and Nap Modes
10000
C_REF = 4.7µF
WITHOUT SLEEP OR NAP
1000
NAP MODE
100
10
1
0.1
NAP = REFRDY
(SLEEP MODE)
NAP = 5V
(SLEEP MODE)
1 10 100 1k 10k 100k
SAMPLE RATE (Hz)
LTC1274/77 • TA02
1