AD7998BRU-1REEL Analog Devices Inc, AD7998BRU-1REEL Datasheet - Page 20

• Manufacturer Part Number: AD7998BRU-1REEL
• Description: IC ADC 12BIT 8CHAN I2C 20TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD7998BRU-1REEL

• Number Of Bits: 12
• Sampling Rate (per Second): 188k
• Data Interface: I²C, Serial
• Number Of Converters: 1
• Power Dissipation (max): 2.2mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP (0.173", 4.40mm Width)
• For Use With: EVAL-AD7998CBZ - BOARD EVALUATION FOR AD7998CBZ
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD7997/AD7998
CONVERSION RESULT REGISTER
The conversion result register is a 16-bit, read-only register that
stores the conversion result from the ADC in straight binary
format. A 2-byte read is necessary to read data from this register.
Table 13 shows the contents of the first byte to be read from the
AD7997/AD7998, and Table 14 shows the contents of the second
byte to be read.
Table 13. Conversion Value Register (First Read)
D15
Alert_Flag
Table 14. Conversion Value Register (Second Read)
D7
B7
The AD7997/AD7998 conversion result consists of an Alert_Flag
bit, three channel identifier bits, and the 10- and 12-bit data
result (MSB first). For the AD7997, the 2 LSBs (D1 and D0) of
the second read contain two 0s. The three channel identification
bits can be used to identify to which of the eight analog input
channels the conversion result corresponds.
The Alert_Flag bit indicates whether the conversion result being
read or any other channel result has violated the limit registers
associated with it. If an ALERT occurs, the master can read the
ALERT status register to obtain more information on where the
ALERT occurred.
LIMIT REGISTERS
The AD7997/AD7998 have four pairs of limit registers. Each
pair stores high and low conversion limits for the first four
analog input channels, CH1 to CH4. Each pair of limit registers
has one associated hysteresis register. All 12 registers are 16 bits
wide; only the 12 LSBs of the registers are used for the AD7997
and AD7998. For the AD7997, the 2 LSBs, D1 and D0 in these
registers, should contain 0s. On power-up, the contents of the
DATA
contents of the DATA
AD7997/AD7998 signal an alert (in either hardware, software,
or both depending on configuration) if the conversion result
moves outside the upper or lower limit set by the limit registers.
There are no limit registers or hysteresis registers associated
with CH5 to CH8.
HIGH
D6
B6
register for each channel is full scale, while the
D14
CH
D5
B5
ID2
LOW
D13
CH
D4
B4
ID1
registers is zero scale by default. The
D12
CH
D3
B3
ID0
D11
M S B
D2
B2
D10
B10
D1
B1
D9
B9
D0
B0
Rev. 0 | Page 20 of 32
D8
B8
DATA
The DATA
registers; only the 12 LSBs of each register are used. This
register stores the upper limit that activates the ALERT output
and/or the Alert_Flag bit in the conversion result register. If the
value in the conversion result register is greater than the value
in the DATA
When the conversion result returns to a value at least N LSBs
below the DATA
Alert_Flag bit are reset. The value of N is taken from the
hysteresis register associated with that channel. The ALERT pin
can also be reset by writing to Bits D2 and D1 in the
configuration register. For the AD7997, D1 and D0 of the
DATA
Table 15. DATA
D15
0
Table 16. DATA
D7
B7
DATA
The DATA
register; only the 12 LSBs of each register are used. The register
stores the lower limit that activates the ALERT output and/or
the Alert_Flag bit in the conversion result register. If the value
in the conversion result register is less than the value in the
DATA
conversion result returns to a value at least N LSBs above the
DATA
bit are reset. The value of N is taken from the hysteresis register
associated with that channel. The ALERT output pin can also be
reset by writing to Bits D2 and D1 in the configuration register.
For the AD7997, D1 to D0 of the DATA
contain 0s.
Table 17. DATA
D15
0
Table 18. DATA
D7
B7
HIGH
HIGH
LOW
LOW
LOW
D14
0
D6
B6
D14
0
D6
B6
Register CH1/CH2/CH3/CH4
register, an ALERT occurs for that channel. When the
register value, the ALERT output pin and Alert_Flag
Register CH1/CH2/CH3/CH4
register should contain 0s.
HIGH
LOW
HIGH
register for each channel is a 16-bit read/write
registers for CH1 to CH 4 are 16-bit read/write
HIGH
D13
0
D5
B5
D13
0
D5
B5
register, an ALERT occurs for that channel.
HIGH
HIGH
LOW
LOW
register value, the ALERT output pin and
Register (First Read/Write)
Register (Second Read/Write)
Register (First Read/Write)
Register (Second Read/Write)
D12
0
D4
D12
0
D4
B4
B4
D11
B11
D3
B3
D11
B11
D3
B3
LOW
D10
B10
D2
B2
D10
B10
D2
B2
register should
D9
B9
D1
B1
D9
B9
D1
B1
D8
B8
D0
B0
D8
B8
D0
B0