
ADM1192
READ VOLTAGE AND/OR CURRENT DATA BYTES
The ADM1192 can be set up to provide information in three
different ways (see the Write Command Byte section). Depending
on how the device is configured, the following data can be read
out of the device after a conversion (or conversions).
Rev. 0 | Page 14 of 20
Voltage and Current Readback
The ADM1192 digitizes both voltage and current. Three bytes
are read out of the device in the format shown in Table 12.
Table 12. Voltage and Current Readback Format
Byte
Contents
B7
B6
1
Voltage
MSBs
2
Current
MSBs
3
LSBs
V3
V2
B5
V9
B4 B3
V8
B2
V6
B1
V5
B0
V4
V11
V10
V7
I11
I10
I9
I8
I7
I6
I5
I4
V1
V0
I3
I2
I1
I0
Voltage Readback
The ADM1192 digitizes voltage only. Two bytes are read out of
the device in the format shown in Table 13.
Table 13. Voltage Only Readback Format
Byte Contents
B7
B6
1
Voltage MSBs
V11 V10 V9 V8 V7 V6
2
Voltage LSBs
V3
V2
B5 B4 B3 B2
B1
V5
0
B0
V4
0
V1 V0 0
0
Current Readback
The ADM1192 digitizes current only. Two bytes are read out of
the device in the format shown in Table 14.
Table 14. Current Only Readback Format
Byte Contents
B7
B6
1
Current MSBs
I11
I10
2
Current LSBs
I3
I2
B5 B4 B3 B2
I9
I8
I1
I0
B1
I5
0
B0
I4
0
I7
0
I6
0
The following series of events occurs when the master receives
three bytes (voltage and current data) from the slave device:
1.
The master device asserts a start condition on SDA.
2.
The master sends the 7-bit slave address, followed by the
read bit (high).
3.
The addressed slave device asserts an acknowledge on SDA.
4.
The master receives the first data byte.
5.
The master asserts an acknowledge on SDA.
6.
The master receives the second data byte.
7.
The master asserts an acknowledge on SDA.
8.
The master receives the third data byte.
9.
The master asserts a no acknowledge on SDA.
10. The master asserts a stop condition on SDA, and the
transaction ends.
For cases where the master is reading voltage only or current
only, only two data bytes are read. Step 7 and Step 8 are not
required.
S
SLAVE
ADDRESS
R A DATA 1
DATA 2
N P
DATA 3
A
A
1
2
3
4
5
6
7
8
9 10
0
Figure 24. Three-Byte Read from ADM1192
S
SLAVE
ADDRESS
R A
REGISTER
ADDRESS
N P
REGISTER
DATA
A
1
2
3
4
5
6
7 8
0
Figure 25. Two-Byte Read from ADM1192
Converting ADC Codes to Voltage and Current Readings
The following equations can be used to convert ADC codes
representing voltage and current from the ADM1175 12-bit
ADC into actual voltage and current values.
Voltage
= (
V
FULLSCALE
/4096) ×
Code
where:
V
FULLSCALE
= 6.65 (7:2 range) or 26.35 (14:1 range).
Code
is the ADC voltage code read from the device (Bit V0
to Bit V11).
Current
= ((
I
FULLSCALE
/4096) ×
Code
)/
Sense Resistor
where:
I
FULLSCALE
= 105.84 mV.
Code
is the ADC current code read from the device (Bit I0 to
Bit I11).
Read Status Register
A single register of status data can also be read from the
ADM1192.
1.
The master device asserts a start condition on SDA.
2.
The master sends the 7-bit slave address, followed by the
read bit (high).
3.
The addressed slave device asserts an acknowledge on SDA.
4.
The master receives the status byte.
5.
The master asserts an acknowledge on SDA.
S
SLAVE
ADDRESS
R A DATA 1 A
1
2
3
4
5
0
Figure 26. Status Read from ADM1192
Table 15 shows the ADM1192 status registers in detail. Note
that Bit 1, Bit 3, and Bit 5 are cleared by writing to Bit 4 of the
ALERT_EN register (CLEAR).