ADC-207MC Murata Power Solutions Inc, ADC-207MC Datasheet - Page 4

• Manufacturer Part Number: ADC-207MC
• Description: Analog To Digital Converter
• Manufacturer: Murata Power Solutions Inc

USING TWO ADC-207’S FOR 8-BIT RESOLUTION
ing 8-bit resolution. The device A provides a typical 7-bit output. The
OVERFLOW signal of device A turns off device A and turns on the device B.
The OVERFLOW signal of device A is also used as MSB for 8-bit operation.
The device B provides the other seven bits from the input signal. Figure 4
shows the circuit connections for the application.
ANALOG IN
CLOCK IN
REFERENCE
+5.12
Two ADC-207’s (A and B) are cascadable for applications requir-
OPTIONAL
MIDSCALE
IN
ADJUST
REFERENCE
GROUND
+5V
+5V
TURN
Figure 4. Using Two ADC-207’s for 8-Bit Operation
10
NOTE: The output data bit numbering is offset by a
bit to the device B’s output.
18
6
8
4
1
9
3
6
8
1
4
9
3
+5 VOLTS
CLOCK IN
GROUND
CS1
+REFERENCE
ANALOG INPUT
CLOCK
CS2
–REFERENCE
CLOCK
+V
–REFERENCE
+REFERENCE
CS1
ANALOG INPUT
CS2
DD
ANALOG GROUND
ANALOG GROUND
+V
DD
18
7
7
0.01µF
DIG GND
DIG GND
OF
OF
B1
B2
B3
B4
B5
B6
B7
B1
B2
B3
B4
B5
B6
B7
10
11
12
13
14
15
16
17
10
11
12
13
14
15
16
17
2
www.murata-ps.com
2
9
4
5
OVERFLOW
BIT 1 (MSB)
6
8
BIT2
BIT3
BIT4
BIT5
BIT6
BIT7
BIT8 (LSB)
20k
BEAT FREQUENCY AND ENVELOPE TESTS
This test uses a 20MHz clock input to the ADC-207 with a 20.002MHz full-
scale sine wave input. Although the converter would not normally be used
in this mode because the input frequency violates Nyquist criteria for full
recovery of signal information, the test is an excellent demonstration of the
ADC-207’s high-frequency performance.
clock is that the output will be a 2kHz sinusoidal digital data array which
"walks" along the actual input at the 2kHz beat note frequency. Any inabil-
ity to follow the 20.002MHz input will be immediately obvious by plotting
the digital data array. Further arithmetic analysis may be done on the data
array to determine spectral purity, harmonic distortion, etc. This test is an
excellent indication of:
is a variation of the previous test but uses a 10.002MHz sinewave input to
give two overlapping cycles when the data is reconstructed by a D/A con-
verter output to an oscilloscope. The scope is triggered by the 20MHz clock
used by the A/D. Any asymmetry between positive and negative portions of
the signal will be very obvious. This test is an excellent indication of slew
rate capability. At the peaks of the envelope, consecutive samples swing
completely through the input voltage range.
10pF
Figure 5 shows an actual ADC-207 plot of the Beat Frequency Test.
The effect of the 2kHz frequency difference between the input and the
Figure 6 shows an actual ADC-207 plot of the Envelope Test. This test
1. Full power input bandwidth of all 128 comparators.
2. Phase response linearity vs. instantaneous signal magnitude.
3. Comparator slew rate limiting.
(Any gain loss would show as signal distortion.)
(Phase problems would show as
improper codes.)
1
2
7-Bit, 20MHz, CMOS Flash A/D Converters
Technical enquiries email: [e-mail], tel:
3
13
12
Figure 3. Optional Pulse Shaping Circuit
11
CLOCK OUT
MDA_ADC-207.B01 Page 4 of 6
ADC-207
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