Data Sheet
AD5412/AD5422
Rev. I | Page 29 of 44
Readback Operation
Readback mode is invoked by setting the address byte and
read address when writing to the input register (se
e Table 9 and
NOP command, which clocks out the data from the previously
By default the SDO pin is disabled after having addressed the
enables the SDO pin in anticipation of data being clocked out.
After the data has been clocked out on SDO, a rising edge on
LATCH disables (tristate) the SDO pin. To read back the data
register, for example, implement the following sequence:
1. Write 0x020001 to the input register. This configures the
part for read mode with the data register selected.
2. Follow this with a second write: a NOP condition, which is
0x000000. During this write, the data from the register is
clocked out on the SDO line.
Table 9. Read Address Decoding
Read Address
Function
00
Read status register
01
Read data register
10
Read control register
POWER-ON STATE
circuit ensures that all registers are loaded with zero-code. As
such, both outputs are disabled; that is, the VOUT and IOUT pins
are in tristate. The +VSENSE pin is internally connected to ground
through a 40 kΩ resistor. Therefore, if the VOUT and +VSENSE pins
are connected together, VOUT is effectively clamped to ground
through a 40 kΩ resistor. Also upon power-on, internal
calibration registers are read, and the data is applied to internal
calibration circuitry. For a reliable read operation, there must be
sufficient voltage on the AVDD supply when the read event is
triggered by the DVCC power supply powering up. Powering up
the DVCC supply after the AVDD supply ensures this. If DVCC and
AVDD are powered up simultaneously or the internal DVCC is
enabled, the supplies should be powered up at a rate greater
than, typically, 500 V/sec or 24 V/50 ms. If this cannot be
power-on; this performs a power-on-reset event, reading the
calibration registers and ensures specified operation of the
internal reference to settle to its correct trim value, 40 s should
be allowed after a successful power on reset.
Voltage Output
For a unipolar voltage output range, the output voltage can be
expressed as
×
=
N
REFIN
OUT
D
Gain
V
2
For a bipolar voltage output range, the output voltage can be
expressed as
2
REFIN
N
REFIN
OUT
V
Gain
D
Gain
V
×
×
=
where:
D is the decimal equivalent of the code loaded to the DAC.
N is the bit resolution of the DAC.
VREFIN is the reference voltage applied at the REFIN pin.
Gain is an internal gain whose value depends on the output
Table 10. Internal Gain Value
Output Range
Gain Value
+5 V
1
+10 V
2
±5 V
2
±10 V
4
Current Output
For the 0 mA to 20 mA, 0 mA to 24 mA, and 4 mA to 20 mA
current output ranges, the output current is respectively
expressed as
D
I
N
OUT
×
=
2
mA
20
D
I
N
OUT
×
=
2
mA
24
mA
4
2
mA
16
+
×
=
D
I
N
OUT
where:
D is the decimal equivalent of the code loaded to the DAC.
N is the bit resolution of the DAC.
Table 11. Input Shift Register Contents for a Read Operation
MSB
LSB
D23
D22
D21
D20
D19
D18
D17
D16
D15 to D2
D1
D0
0
1
0
Read address
1
X = don’t care.