kad5510p Kenet Inc., kad5510p Datasheet - Page 19

• Manufacturer Part Number: kad5510p
• Description: Low Power 10-bit, 250/210/170/125msps Adc
• Manufacturer: Kenet Inc.

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 21. 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 can be controlled
through the SPI port. Details on this are contained in “Serial
Peripheral Interface” on page 21.
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 30 shows this
operation.
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 31.
Mapping of the input voltage to the various data formats is
shown in Table 2.
–Full Scale + 1LSB
+Full Scale – 1LSB
INPUT VOLTAGE
–Full Scale
+Full Scale
Mid–Scale
NAPSLP PIN
AVDD
AVSS
Float
TABLE 1. NAPSLP PIN SETTINGS
19
OFFSET BINARY
000 00 000 00
000 00 000 01
100 00 000 00
111 11 111 10
111 11 111 11
TABLE 2. INPUT VOLTAGE TO OUTPUT CODE MAPPING
Normal
MODE
Sleep
Nap
KAD5510P
TWO’S COMPLEMENT
100 00 000 00
100 00 000 01
000 00 000 00
011 11 111 10
011 11 111 11
GRAY CODE
GRAY CODE
BINARY
BINARY
FIGURE 30. BINARY TO GRAY CODE CONVERSION
FIGURE 31. GRAY CODE TO BINARY CONVERSION
9
9
9
9
8
8
8
8
7
7
7
7
000 00 000 00
000 00 000 01
110 00 000 00
100 00 000 01
100 00 000 00
• • • •
• • • •
• • • •
GRAY CODE
• • • •
• • • •
• • • •
• • • •
1
January 3, 2011
1
1
1
0
FN7693.1
0
0
0