kad5512p-21q72ep-i Intersil Corporation, kad5512p-21q72ep-i Datasheet - Page 20

• Manufacturer Part Number: kad5512p-21q72ep-i
• Description: Low Power 12-bit, 250/210/170/125msps Adc
• Manufacturer: Intersil Corporation

increase if the clock is stopped, since the internal DLL can
take up to 52µs to regain lock at 250MSPS.
By default after the device is powered on, the operational
state is controlled by the NAPSLP pin as shown in Table 3.
The power-down mode can also be controlled through the
SPI port, which overrides the NAPSLP pin setting. Details on
this are contained in “Serial Peripheral Interface” on
page 22. This is an indexed function when controlled from
the SPI, but a global function when driven from the pin.
Data Format
Output data can be presented in three formats: two’s
complement, Gray code and offset binary. The data format is
selected via the OUTFMT pin as shown in Table 4.
The data format can also be controlled through the SPI port,
which overrides the OUTFMT pin setting. Details on this are
contained in “Serial Peripheral Interface” on page 22.
Offset binary coding maps the most negative input voltage to
code 0x000 (all zeros) and the most positive input to 0xFFF
(all ones). Two’s complement coding simply complements
the MSB of the offset binary representation.
When calculating Gray code the MSB is unchanged. The
remaining bits are computed as the XOR of the current bit
position and the next most significant bit. Figure 33 shows
this operation.
GRAY CODE
FIGURE 33. BINARY TO GRAY CODE CONVERSION
BINARY
NAPSLP PIN
OUTFMT PIN
AVSS
AVDD
AVSS
AVDD
Float
Float
TABLE 4. OUTFMT PIN SETTINGS
TABLE 3. NAPSLP PIN SETTINGS
11
11
10
10
20
9
9
Two’s Complement
Offset Binary
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Gray Code
Normal
MODE
MODE
Sleep
Nap
1
1
0
0
KAD5512P
Converting back to offset binary from Gray code must be
done recursively, using the result of each bit for the next
lower bit as shown in Figure 34.
Mapping of the input voltage to the various data formats is
shown in Table 5.
–Full Scale 000 00 000 00 00 100 00 000 00 00 000 00 000 00 00
–Full Scale
+Full Scale
+Full Scale 111 11 111 11 11
VOLTAGE OFFSET BINARY
Mid–Scale 100 00 000 00 00 000 00 000 00 00 110 00 000 00 00
+ 1LSB
– 1LSB
INPUT
TABLE 5. INPUT VOLTAGE TO OUTPUT CODE MAPPING
FIGURE 34. GRAY CODE TO BINARY CONVERSION
GRAY CODE
BINARY
000 00 000 00 01 100 00 000 00 01 000 00 000 00 01
111 11 111 11 10
11
11
10
10
011 11 111 11 10 100 00 000 00 01
011 11 111 111 1 100 00 000 00 00
COMPLEMENT
9
TWO’S
9
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GRAY CODE
January 16, 2009
1
1
FN6807.1
0
0