MAX127ACAI(2012) Просмотр технического описания (PDF) - Maxim Integrated
Номер в каталоге
Компоненты Описание
производитель
MAX127ACAI Datasheet PDF : 16 Pages
| |||
MAX127/MAX128
Multirange, +5V, 12-Bit DAS with
2-Wire Serial Interface
Transfer Function
Output data coding for the MAX127/MAX128 is binary
in unipolar mode with 1 LSB = (FS/4096) and two’s
complement binary in bipolar mode with 1 LSB = [(2 x
|FS|)/4096]. Code transitions occur halfway between
successive-integer LSB values. Figures 13a and 13b
show the input/output (I/O) transfer functions for unipolar
and bipolar operations, respectively. For full-scale (FS)
values, refer to Table 3.
OUTPUT CODE
11... 111
11... 110
11... 101
FULL-SCALE
TRANSITION
1 LSB =
FS
4096
Layout, Grounding, and Bypassing
Careful PCB layout is essential for best system perfor-
mance. For best performance, use a ground plane. To
reduce crosstalk and noise injection, keep analog and
digital signals separate. Connect analog grounds and
DGND in a star configuration to AGND. For noise-free
operation, ensure the ground return from AGND to the
supply ground is low impedance and as short as possible.
Connect the logic grounds directly to the supply ground.
Bypass VDD with 0.1μF and 4.7μF capacitors to AGND to
minimize highand low-frequency fluctuations. If the supply
is excessively noisy, connect a 5Ω resistor between the
supply and VDD, as shown in Figure 14.
00... 011
00... 010
00... 001
00... 000
01 2 3
INPUT VOLTAGE (LSB)
Figure 13a. Unipolar Transfer Function
FS
FS - 3/2 LSB
OUTPUT CODE
011... 111
011... 110
1 LSB =
2 FS
4096
SUPPLY
+5V
GND
R* = 5Ω
4.7µF
0.1µF
**
VDD
AGND
MAX127
MAX128
DGND
+5V DGND
DIGITAL
CIRCUITRY
* OPTIONAL
** CONNECT AGND AND DGND WITH A GROUND PLANE OR A SHORT TRACE.
Figure 14. Power-Supply Grounding Connection
000... 001
000... 000
111... 111
100... 010
100... 001
100... 000
-FS
0
+FS - 1 LSB
INPUT VOLTAGE (LSB)
Figure 13b. Bipolar Transfer Function
www.maximintegrated.com
Maxim Integrated │ 15
Share Link: 