MAX148 Maxim, MAX148 Datasheet - Page 20

• Manufacturer Part Number: MAX148
• Description: +2.7V to +5.25V / Low-Power / 8-Channel / Serial 10-Bit ADCs
• Manufacturer: Maxim

+2.7V to +5.25V, Low-Power, 8-Channel,
Serial 10-Bit ADCs
Figure 20. MAX148/MAX149 QSPI Connections, External Reference
Figure 21. MAX148/MAX149-to-TMS320 Serial Interface
20
______________________________________________________________________________________
TMS320LC3x
ANALOG
INPUTS
CLKX
CLKR
FSR
DX
DR
XF
10
1
2
3
4
5
6
7
8
9
SHDN
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
MAX148
MAX149
CS
SCLK
DIN
DOUT
SSTRB
REFADJ
SSTRB
DGND
AGND
DOUT
SCLK
VREF
V
DIN
CS
DD
MAX148
MAX149
20
19
17
16
15
14
13
12
11
18
0.1 F
0.1 F
+2.5V
For best performance, use printed circuit boards.
Wire-wrap boards are not recommended. Board layout
should ensure that digital and analog signal lines are
separated from each other. Do not run analog and digi-
tal (especially clock) lines parallel to one another, or
digital lines underneath the ADC package.
Figure 19 shows the recommended system ground
connections. Establish a single-point analog ground
(star ground point) at AGND, separate from the logic
ground. Connect all other analog grounds and DGND
to the star ground. No other digital system ground
should be connected to this ground. For lowest-noise
operation, the ground return to the star ground’s power
supply should be low impedance and as short as
possible.
High-frequency noise in the V
affect the high-speed comparator in the ADC. Bypass
the supply to the star ground with 0.1µF and 1µF
capacitors close to pin 20 of the MAX148/MAX149.
Minimize capacitor lead lengths for best supply-noise
rejection. If the power supply is very noisy, a 10Ω resis-
tor can be connected as a lowpass filter (Figure 19).
1 F
+3V
Layout, Grounding, and Bypassing
+3V
(POWER SUPPLIES)
SCK
PCS0
MOSI
MISO
MC683XX
(GND)
DD
power supply may