MAX1204 Maxim, MAX1204 Datasheet - Page 19

• Manufacturer Part Number: MAX1204
• Description: 5v / 8-cHANNEL / sERIAL / 10-bIT adc WITH 3v dIGITAL iNTERFACE
• Manufacturer: Maxim

Figure 14a. MAX1204 Supply Current vs. Sample Rate/Second,
FULLPD, 400kHz Clock
Figure 14b. MAX1204 Supply Current vs. Sample Rate/Second,
FASTPD, 2MHz Clock
Figure 17, the Reference-Adjust Circuit, shows how to
adjust ADC gain in applications that use the internal
reference. The circuit provides ±1.5% (±16LSBs) of
gain-adjustment range.
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 digital
10,000
1000
1000
100
100
10
10
1
0
0
2ms FASTPD WAIT
400kHz EXTERNAL CLOCK
INTERNAL COMPENSATION
50
2k
CONVERSIONS PER CHANNEL PER SECOND
CONVERSIONS PER CHANNEL PER SECOND
8 CHANNELS
100
Layout, Grounding, Bypassing
______________________________________________________________________________________
4k
150
FULL POWER-DOWN
FAST POWER-DOWN
6k
2MHz EXTERNAL CLOCK
EXTERNAL COMPENSATION
50µs WAIT
200
8k
250
10k
300
12k
350
5V, 8-Channel, Serial, 10-Bit ADC
8 CHANNELS
1 CHANNEL
1 CHANNEL
14k
400
450
16k
500
18k
with 3V Digital Interface
(especially clock) lines parallel to one another, or digital
lines underneath the ADC package.
Figure 18 shows the recommended system-ground con-
nections. Establish a single-point analog ground (star
ground point) at GND. Connect all other analog grounds
to this ground. No other digital system ground should be
connected to this single-point analog ground. The
ground return to the power supply should be low imped-
ance and as short as possible for noise-free operation.
High-frequency noise in the V
the high-speed comparator in the ADC. Bypass these
supplies to the single-point analog ground with 0.1µF and
4.7µF bypass capacitors close to the MAX1204. Minimize
capacitor lead lengths for best supply-noise rejection. If
the +5V power supply is very noisy, a 10Ω resistor can
be connected as a lowpass filter, as shown in Figure 18.
Figure 14c. Typical Power-Up Delay vs. Time in Shutdown
3.0
2.5
2.0
1.5
1.0
0.5
0
0.0001 0.001
TIME IN SHUTDOWN (sec)
0.01
DD
0.1
power supply may affect
1
10
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