LTC1278
12-Bit, 500ksps Sampling
A/D Converter with Shutdown
FEATURES
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DESCRIPTIO
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Single Supply 5V or
±5V
Operation
Two Speed Grades,500ksps (LTC1278-5)
400ksps (LTC1278-4)
70dB S/(N + D) and 74dB THD at Nyquist
No Missing Codes Over Temperature
75mW (Typ) Power Dissipation
Power Shutdown with Instant Wake-Up
Internal Reference Can Be Overdriven Externally
Internal Synchronized Clock; No Clock Required
High Impedance Analog Input
0V to 5V or
±2.5V
Input Range
New Flexible, Friendly Parallel Interface to DSPs
and FIFOs
24-Pin Narrow PDIP and SW Packages
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.
APPLICATI
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High Speed Data Acquisition
Digital Signal Processing
Multiplexed Data Acquisition Systems
Audio and Telecom Processing
Spectrum Analysis
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
2.42V
REFERENCE
OUTPUT
Single 5V Supply, 500kHz, 12-Bit Sampling A/D Converter
LTC1278-5
ANALOG INPUT 1 A
AV
DD
(0V TO 5V) 2
IN
V
REF
V
SS
3
AGND
BUSY
0.1µF
4
D11(MSB) CS
5
D10
RD
6
D9
CONVST
7
D8
SHDN
8
D7
DV
DD
9
D6
D0
10
12-BIT
D5
D1
PARALLEL
11
D4
D2
BUS
12
DGND
D3
5V
24
23
22
21
20
19
18
17
16
15
14
13
10µF
µP
CONTROL
LINES
CONVERSION START INPUT
POWER DOWN INPUT
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
12
74
68
NYQUIST
FREQUENCY
62
56
+
+
10µF
0.1µF
EFFECTIVE NUMBER OF BITS
11
10
9
8
7
6
5
4
3
2
1
0
10k
f
SAMPLE
= 500kHz
100k
INPUT FREQUENCY (Hz)
1M
LTC1278 • TA01
U
S/(N+D) (dB)
2M
LT1278 G4
UO
UO
1
LINER [ LINEAR TECHNOLOGY ]
