Datasheet

11
LTC1564
1564fa
TYPICAL APPLICATIO S
U
16-Bit Output, Sampling Rate to 500ksps, Analog Bandwidth to 150kHz, Gain to 24dB.
(For More Information, See
Linear Technology Magazine, May 2001)
2-Chip Flexible DSP Front End with Amplification,
Antialias Filtering and A/D Conversion
Boosting a 100mV
RMS
Input Signal to Nearly Fill the Input Range of the LTC1608 ADC. Input Frequency of 40kHz,
LTC1608 f
SAMPLE
= 204.8ksps, LTC1564 is Set for f
C
= 50kHz and Gain of 16 (F = 0101, G = 1111). Measured THD
is 86dB, HD
2
= –88dB, SNR = 85dB with 100mV
RMS
Input. Dynamic Range of Approximately 115dB
4096-Point FFT Spectrum
with Low Level Input
FREQUENCY (kHz)
0
–60
–40
0
76.8
1564 TA04
–80
–100
25.6 51.2 102.4
–120
–140
–20
AMPLITUDE (dB)
2.2µF
1µF
1µF
10Ω
22µF
4
6
DIFFERENTIAL
ANALOG INPUT
± 2.5V
REFCOMP
CONTROL
LOGIC
AND
TIMING
B15 TO B0
16-BIT
SAMPLING
ADC
–
+
1µF
5V OR
3V
µP
CONTROL
LINES
D15 TO D0
OUTPUT
BUFFERS
16-BIT
PARALLEL
BUS
11 TO 26
OGND
OV
DD
28
1564 TA03
29
1
2
A
IN
+
A
IN
–
SHDN
CS
CONVST
RD
BUSY
33
32
31
30
27
7.5k
LTC1608
3
36
35
10
9
5V
5V
AV
DD
AV
DD
DV
DD
DGND
V
REF
8
AGND
AGND
7
AGND
5
AGND
34
–5V
V
SS
1µF
2.5V
REF
1µF
1.75X
+
V
+
EN V
–
OUT
AGND
IN
16
CS/
HOLD RST F
4 5 6 7 8 9 10 11 12
15
1
2314
13
G
LTC1564
5V
–5V
0.1µF
0.1µF
249Ω
1% METAL FILM
249Ω
1% METAL FILM
C1*
FILTER CONTROL
ANTIALIAS FILTER/AMP ADC
A
V
f
C
INPUT
+
–
*C1 IS A 1000pF NPO, SURFACE MOUNT DEVICE
PLACE AS CLOSE AS POSSIBLE TO THE LTC1608 INPUT PINS
A
V
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.