AD7416/AD7417/AD7418
CONFIGURATION REGISTER (ADDRESS 01h)
ADC VALUE REGISTER (ADDRESS 04h)
The Configuration Register is an 8-bit, read/write register that
is used to set the operating modes of the AD7416/AD7417/
AD7418. Bits D7 to D5 control the channel selection as
outlined in Table VI. These bits should always be 0, 0, 0 for
the AD7416. Bits D4 and 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 V. Configuration Register
The ADC Value Register is a 16-bit, read-only register whose
10 MSBs store the value produced by the ADC in binary for-
mat. Bits 5 to 0 are unused. Table IX shows the ADC Value
Register with 10 MSBs containing the ADC conversion request.
Table IX. ADC Value Register
D15
MSB
D14 D13 D12
B8
B7
B6
D11
B5
D10
B4
D9
B3
D8
B2
D7
B1
D6
LSB
D7
D6
D5
D4
D3
D2
OTI
Polarity
D1
Cmp/
Int
D0
Shut-
down
ADC Transfer Function
Channel
Selection
Fault
Queue
The designed code transitions occur at successive integer LSB
values (i.e., 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 7.
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 chan-
nel address for all parts is the same, CH0. The address for the
analog input channel on the AD7418 is CH4. Table VI outlines
the channel selection on the parts, while Table VII shows the
fault queue settings. D1 and D2 are explained in the OTI Out-
put section.
Table VI. Channel Selection
111...111
111...110
ADC CODE
111...000
1LSB = V REF/1024
011...111
000...010
000...001
000...000
0V 1/2LSB
+VREF – 1LSB
ANALOG INPUT
D7
0
0
0
0
1
D6
0
0
1
1
0
D5
0
1
0
1
0
Channel Selection
Temperature Sensor (All Parts)
A
IN1
(AD7417 Only)
A
IN2
(AD7417 Only)
A
IN3
(AD7417 Only)
A
IN4
(AD7417) and A
IN
(AD7418)
Figure 7. Ideal Transfer Function Characteristic
for the AD7417/AD7418
CONFIG2 REGISTER (ADDRESS 05h)
Table VII. Fault Queue Settings
D4
0
0
1
1
D3
0
1
0
1
Number of Faults
1 (Power-Up Default)
2
4
6
A second configuration register is included in the AD7417/
AD7418 for the functionality of the CONVST pin. It is an 8-bit
register with Bits D5 to D0 being left at 0. Bit D7 determines
whether the AD7417/AD7418 should be operated in its default
mode (D7 = 0), performing conversions every 355
µs
or in its
CONVST
pin mode (D7 = 1), where conversions will start only
when the
CONVST
pin is used. Bit 6 contains the Test 1 Bit.
When this bit is 0, the I
2
C filters are enabled (default). A 1
disables the filters.
Table X. CONFIG2 Register
T
HYST
SETPOINT REGISTER (ADDRESS 02h)
D7
Conversion Mode
D6
D5
D4
0
D3
0
D2
0
D1
0
D0
0
The T
HYST
Setpoint Register is a 16-bit, read/write register whose
nine MSBs store the T
HYST
setpoint in twos complement for-
mat equivalent to the nine MSBs of the Temperature Value
Register. Bits 6 to 0 are unused.
T
OTI
SETPOINT REGISTER (ADDRESS 03h)
Test 1 0
SERIAL BUS INTERFACE
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. Bits 6 to 0 are unused.
Table VIII. Setpoint Registers
Control of the AD7416/AD7417/AD7418 is carried out via the
I
2
C compatible serial bus. The AD7416/AD7417/AD7418 is
connected to this bus as a slave device, under the control of a
master device, e.g., the processor.
SERIAL BUS ADDRESS
D15
MSB
D14
B7
D13
B6
D12
B5
D11
B4
D10
B3
D9
B2
D8
B1
D7
LSB
As with all I
2
C compatible devices, the AD7416/AD7417/AD7418
have a 7-bit serial address. The four MSBs of this address for the
AD7416 are set to 1001; the AD7417 are set to 0101, while the
three LSBs can be set by the user by connecting the A2 to A0
pins to either V
DD
or GND. By giving them different addresses, up
to eight AD7416/AD7417s can be connected to a single serial bus,
–11–
REV. G
AD [ ANALOG DEVICES ]
