
1
LTC1278
S
FEATURE
D
U
ESCRIPTIO
The LTC
1278 is a 1.6
s, 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 1.6
s 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.
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
12-Bit, 500ksps Sampling
A/D Converter with Shutdown
U
A
O
PPLICATI
TYPICAL
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
INPUT FREQUENCY (Hz)
10k
0
EFFECTIVE
NUMBER
OF
BITS
S/(N
+
D)
(dB)
3
5
7
10
100k
1M
2M
LT1278 G4
1
4
6
9
12
11
62
56
74
68
8
2
fSAMPLE = 500kHz
NYQUIST
FREQUENCY
U
S
A
O
PPLICATI
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.
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13
AIN
VREF
AGND
D11(MSB)
D10
D9
D8
D7
D6
D5
D4
DGND
AVDD
VSS
BUSY
CS
RD
CONVST
SHDN
DVDD
D0
D1
D2
D3
LTC1278-5
+
0.1
F
10
F
2.42V
REFERENCE
OUTPUT
ANALOG INPUT
(0V TO 5V)
10
F
0.1
F
5V
12-BIT
PARALLEL
BUS
P CONTROL
LINES
LTC1278 TA01
+
CONVERSION START INPUT
POWER DOWN INPUT
Single 5V Supply, 500kHz, 12-Bit Sampling A/D Converter