LTC1278 Datasheet, PDF (1/16 Pages) Linear Technology – 12-Bit, 500ksps Sampling A/D Converter with Shutdown

LTC1278
12-Bit, 500ksps Sampling
A/D Converter with Shutdown
FEATURES
s _{Single Supply 5V or ±5V Operation}
s _{Two Speed Grades,500ksps (LTC1278-5)}
400ksps (LTC1278-4)
s _{70dB S/(N + D) and 74dB THD at Nyquist}
s _{No Missing Codes Over Temperature}
s _{75mW (Typ) Power Dissipation}
s _{Power Shutdown with Instant Wake-Up}
s _{Internal Reference Can Be Overdriven Externally}
s _{Internal Synchronized Clock; No Clock Required}
s _{High Impedance Analog Input}
s _{0V to 5V or ±2.5V Input Range}
s _{New Flexible, Friendly Parallel Interface to DSPs}
and FIFOs
s _{24-Pin Narrow PDIP and SW Packages}
APPLICATI S
s _{High Speed Data Acquisition}
s _{Digital Signal Processing}
s _{Multiplexed Data Acquisition Systems}
s _{Audio and Telecom Processing}
s _{Spectrum Analysis}
, LTC and LT are registered trademarks of Linear Technology Corporation.
DESCRIPTIO
The LTC^®1278 is a 1.6µs, 500ksps, sampling 12-bit A/D
converter that draws only 75mW from a single 5V or ±5V
supplies. This easy-to-use device comes complete with
a 200ns sample-and-hold, a precision reference and an
internally trimmed clock. Unipolar and bipolar conver-
sion modes add to the flexibility of the ADC. The low
power dissipation is made even more attractive by a
8.5mW power-down feature. Instant wake-up from shut-
down allows the converter to be powered down even
during brief inactive periods.
The LTC1278 converts 0V to 5V unipolar inputs from a
single 5V supply and ±2.5V bipolar inputs from ±5V
supplies. Maximum DC specs include ±1LSB INL and
±1LSB DNL. Outstanding guaranteed AC performance
includes 70dB S/(N + D) and 78dB THD at the input
frequency of 100kHz over temperature.
The internal clock is trimmed for 1.6µs conversion time.
The clock automatically synchronizes to each sample
command, eliminating problems with asynchronous clock
noise found in competitive devices. A separate convert
start input and a data ready signal (BUSY) ease connec-
tions to FIFOs, DSPs and microprocessors.
TYPICAL APPLICATI
Single 5V Supply, 500kHz, 12-Bit Sampling A/D Converter
2.42V
REFERENCE
OUTPUT
+
10µF
LTC1278-5
ANALOG INPUT
(0V TO 5V)
1
2
A_IN
24
AV_{DD 23}
3 ^VREF
V_{SS 22}
0.1µF
AGND BUSY
4
21
D11(MSB) CS
5
20
D10
RD
6
19
D9 CONVST
7
18
D8
SHDN
8
17
D7
9
DV_{DD 16}
D6
D0
12-BIT
PARALLEL
10
D5
11
15
D1
14
BUS
D4
D2
12
13
DGND
D3
5V
+
10µF
0.1µF
µP CONTROL
LINES
CONVERSION START INPUT
POWER DOWN INPUT
LTC1278 • TA01
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
12
11
10
NYQUIST
9
FREQUENCY
8
7
6
5
4
3
2
1 f_SAMPLE = 500kHz
0
10k
100k
INPUT FREQUENCY (Hz)
74
68
62
56
1M 2M
LT1278 G4
1