LTC1609 LINER [Linear Technology], LTC1609 Datasheet - Page 19

• Manufacturer Part Number: LTC1609
• Description: 16-Bit, 200ksps, Serial ADC with Multiple Input Ranges
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
Output Data Format
The SB/BTC pin controls the format of the serial digital
output word. With the pin tied high the format is straight
binary. With the pin tied low the data format is two’s
complement. See Table 1c.
Board Layout, Power Supplies and Decoupling
Wire wrap boards are not recommended for high resolu-
tion or high speed A/D converters. To obtain the best
performance from the LTC1609, a printed circuit board is
required. Layout for the printed circuit board should
ensure the digital and analog signal lines are separated as
much as possible. In particular, care should be taken not
to run any digital track alongside an analog signal track or
underneath the ADC. The analog input should be screened
by AGND.
BUSY
DCLK
DATA
OUT
R/C
Figure 14. Data Output from Cascading Two (CS = Low, TAG (#2) = Low) LTC1609s Together
0
U
1
B15
U
2
B14 B13 B12 B11 B10
3
W
4
5
6
U
7
B9
8
DEVICE DATA #1
B8
9
B7
10
B6
Pay particular attention to the design of the analog and
digital ground planes. Placing the bypass capacitor as
close as possible to the V
and reference buffer output is very important. Low imped-
ance common returns for these bypass capacitors are
essential to low noise operation of the ADC, and the foil
width for these tracks should be as wide as possible. Also,
since any potential difference in grounds between the
signal source and ADC appears as an error voltage in
series with the input signal, attention should be paid to
reducing the ground circuit impedance as much as pos-
sible. The digital output latches and the onboard sampling
clock have been placed on the digital ground plane. The
two ground planes are tied together at the power supply
ground connection.
A “postage stamp” (1.6in
available and allows fast in-situ evaluation of the LTC1609.
See Figures 15a through 15d, inclusive.
11
B5
12
B4
13
B3
14
B2
15
B1
16
B0
DIG
17
NULL
BIT
and V
1.5in) evaluation board is
18
B15
19
B14 B13 B12 B11 B10
ANA
DEVICE DATA #2
20
pins, the REF pin
LTC1609
21
22
19
23
1609 F14
1609fa
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