Datasheet

AD7416/AD7417/AD7418
Rev. I | Page 13 of 24
Table 8. Register Addresses
P2 P1 P0 Registers
0 0 0 Temperature value
0 0 1 Configuration register
0 1 0 T
HYST
setpoint
0 1 1 T
OTI
setpoint
1 0 0 ADC value (AD7417/AD7418 only)
1 0 1 Config2 (AD7417/AD7418 only)
Temperature Value Register (Address 0x00)
The temperature value register is a 16-bit, read-only register
whose 10 MSBs store the temperature reading from the ADC in
10-bit twos complement format. Bit D5 to Bit D0 are unused.
Table 9. Temperature Value Register
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6
MSB B8 B7 B6 B5 B4 B3 B2 B1 LSB
The temperature data format is shown in Table 10. This shows
the full theoretical range of the ADC from −128°C to +127°C,
but in practice, the temperature measurement range is limited
to the operating temperature range of the device.
Table 10. Temperature Data Format
Temperature Digital Output
−128°C 10 0000 0000
−125°C 10 0000 1100
−100°C 10 0111 0000
−75°C 10 1101 0100
−50°C 11 0011 1000
−25°C 11 1001 1100
−10°C 11 1101 1000
−0.25°C 11 1111 1111
0°C 00 0000 0000
+0.25°C 00 0000 0001
+10°C 00 0010 1000
+25°C 00 0110 0100
+50°C 00 1100 1000
+75°C 01 0010 1100
+100°C 01 1001 0000
+125°C 01 1111 0100
+127°C 01 1111 1100
Configuration Register (Address 0x01)
The configuration register is an 8-bit, read/write register that is
used to set the operating modes of the AD7416/AD7417/AD7418.
Bit D7 to Bit D5 control the channel selection as outlined in
Table 12. Bits[D7:D5] should always be set to 000 for the AD7416.
Bit D4 and Bit D3 are used to set the length of the fault queue.
D2 sets the sense of the OTI output. D1 selects the comparator
or interrupt mode of operation, and D0 = 1 selects the shutdown
mode (default: D0 = 0).
Table 11. Configuration Register
D7 D6 D5 D4 D3 D2 D1 D0
Channel
selection
Fault
queue
OTI
polarity
Cmp/Int Shutdown
The AD7416 contains a temperature-only channel; the AD7417
has four analog input channels and a temperature channel; and
the AD7418 has two channels, a temperature channel, and an
analog input channel. The temperature channel address for all
parts is the same, Channel 0. The address for the analog input
channel on the AD7418 is Channel 4. Table 12 outlines the
channel selection on the parts, and Tabl e 13 shows the fault
queue settings. D1 and D2 are explained in the OTI Output
section.
Table 12. Channel Selection
D7 D6 D5 Channel Selection
0 0 0 Temperature sensor (all parts), Channel 0
0 0 1 A
IN1
(AD7417 only), Channel 1
0 1 0 A
IN2
(AD7417 only), Channel 2
0 1 1 A
IN3
(AD7417 only), Channel 3
1 0 0 A
IN4
(AD7417) and A
IN
(AD7418), Channel 4
Table 13. Fault Queue Settings
D4 D3 Number of Faults
0 0 1 (power-up default)
0 1 2
1 0 4
1 1 6
T
HYST
Setpoint Register (Address 0x02)
The T
HYST
setpoint register is a 16-bit, read/write register whose
nine MSBs store the T
HYST
setpoint in twos complement format
equivalent to the nine MSBs of the temperature value register.
Bit D6 to Bit D0 are unused.
T
OTI
Setpoint Register (Address 0x03)
The T
OTI
setpoint register is a 16-bit, read/write register whose
nine MSBs store the T
OTI
setpoint in twos complement format
equivalent to the nine MSBs of the temperature value register.
Bit 6 to Bit 0 are unused.
Table 14. T
HYST
Setpoint and T
OTI
Setpoint Registers
D15 D14 D13 D12 D11 D10 D9 D8 D7
MSB B7 B6 B5 B4 B3 B2 B1 LSB
ADC Value Register (Address 0x04)
The ADC value register is a 16-bit, read-only register whose
10 MSBs store the value produced by the ADC in binary format.
Bit D5 to Bit D0 are unused. Table 15 shows the ADC value
register with 10 MSBs containing the ADC conversion request.
Table 15. ADC Value Register
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6
MSB B8 B7 B6 B5 B4 B3 B2 B1 LSB
ADC Transfer Function
The designed code transitions occur at successive integer
LSB values (that is, 1 LSB, 2 LSB, and so on). The LSB size =
VREF/1024. The ideal transfer function characteristic for the
AD7417 and AD7418 ADC is shown in Figure 14.