MAX1204ACPP Maxim Integrated, MAX1204ACPP Datasheet - Page 18

• Manufacturer Part Number: MAX1204ACPP
• Description: Analog to Digital Converters - ADC
• Manufacturer: Maxim Integrated

Specifications of MAX1204ACPP

• Number Of Channels: 8/4
• Architecture: SAR
• Conversion Rate: 133 KSPs
• Resolution: 10 bit
• Input Type: Single-Ended/Differential
• Snr: 66 dB
• Interface Type: 4-Wire (SPI, Microwire, TMS320)
• Operating Supply Voltage: 4.75 V to 5.25 V
• Maximum Operating Temperature: + 70 C
• Package / Case: PDIP N
• Maximum Power Dissipation: 640 mW
• Minimum Operating Temperature: 0 C
• Number Of Converters: 1
• Voltage Reference: 4.096 V

5V, 8-Channel, Serial, 10-Bit ADC
with 3V Digital Interface
Figure 14b shows power consumption with external-
reference compensation in fast power-down, with one and
eight channels converted. The external 4.7µF compensa-
tion requires a 50µs wait after power-up. This circuit com-
bines fast multichannel conversion with the lowest power
consumption possible. Full power-down mode can
increase power savings in applications where the
MAX1204 is inactive for long periods of time, but where
intermittent bursts of high-speed conversions are required.
The MAX1204 can be used with an internal or external
reference. An external reference can be connected
directly at the REF terminal or at the REFADJ pin.
Figure 12c. Additional I
for Each Digital Input at a Logic 1
Figure 13. MAX1204 FULLPD/FASTPD Power-Up Sequence
MAX1204
18
DIN
REFADJ
REF
1
40
35
30
25
20
15
10
FULLPD
External and Internal References
5
0
-60
2.5V
0V
4V
0V
0 0
Lowest Power at Higher Throughputs
(V
DD
-20
(V
- V
DD
DD
IH
- V
TEMPERATURE (°C)
) = 1.95V
Shutdown Supply Current vs. V
IH
20
) = 2.55V
(V
DD
60
(ZEROS)
- V
IH
) = 2.25V
100
COMPLETE CONVERSION SEQUENCE
140
1
τ = RC = 20kΩ x C
FASTPD
2ms WAIT
0 1
IH
REFADJ
An internal buffer is designed to provide 4.096V at REF
for the MAX1204. Its internally trimmed 2.44V reference
is buffered with a 1.68 nominal gain.
The MAX1204’s full-scale range with internal reference is
4.096V with unipolar inputs and ±2.048V with bipolar
inputs. The internal reference voltage is adjustable to
±1.5% with the circuit of Figure 17.
An external reference can be placed at either the input
(REFADJ) or the output (REF) of the MAX1204’s internal
buffer amplifier. The REFADJ input impedance is typical-
ly 20kΩ. At REF, the input impedance is a minimum of
12kΩ for DC currents. During conversion, an external
reference at REF must deliver up to 350µA DC load cur-
rent and have an output impedance of 10Ω or less. If the
reference has higher output impedance or is noisy,
bypass it close to the REF pin with a 4.7µF capacitor.
Using the buffered REFADJ input makes buffering of
the external reference unnecessary. To use the direct
REF input, disable the internal buffer by tying REFADJ
to V
REFADJ can be as much as 25µA with REFADJ tied to
V
current in power-down.
Figure 15 depicts the nominal, unipolar input/output
(I/O) transfer function, and Figure 16 shows the bipolar
I/O transfer function. Code transitions occur halfway
between successive integer LSB values. Output coding
is binary with 1 LSB = 4mV (4.096V/1024) for
unipolar operation and 1 LSB = 4mV [(4.096V/2 -
-4.096V/2)/1024] for bipolar operation.
DD
t
BUFFEN
1
. Pull REFADJ to GND to minimize the input bias
DD
NOPD
. In power-down, the input bias current to
CH1
≈ 15µs
Transfer Function and Gain Adjust
1
1
1
FULLPD
CH7
0 0
(ZEROS)
External Reference
Internal Reference
1
FASTPD
Maxim Integrated
0 1