EVAL-AD5383EB AD [Analog Devices], EVAL-AD5383EB Datasheet - Page 34

• Manufacturer Part Number: EVAL-AD5383EB
• Description: 32-Channel, 3 V/5 V, Single-Supply, 12-Bit, Voltage Output DAC
• Manufacturer: AD [Analog Devices]

AD5383
AD5383 MONITOR FUNCTION
The AD5383 contains a channel monitor function that consists
of a multiplexer addressed via the interface, allowing any chan-
nel output to be routed to this pin for monitoring using an
external ADC. The channel monitor function must be enabled
in the control register before any channels are routed to
MON_OUT. Table 18 contains the decoding information
needed to route any channel to MON_OUT. Selecting Channel
Address 63 three-states MON_OUT. Figure 41 shows a typical
monitoring circuit implemented using a 12-bit SAR ADC in a
6-lead SOT-23 package. The controller output port selects the
channel to be monitored, and the input port reads the converted
data from the ADC.
TOGGLE MODE FUNCTION
The toggle mode function allows an output signal to be genera-
ted using the LDAC control signal that switches between two
DAC data registers. This function is configured using the SFR
control register as follows. A write with REG1 = REG0 = 0 and
A4–A0 = 01100 specifies a control register write. The toggle
mode function is enabled in groups of eight channels using Bits
CR3 to CR0 in the control register. See the AD5383 control
register description. Figure 42 shows a block diagram of toggle
mode implementation. Each of the 32 DAC channels on the
AD5383 contain an A and B data register. Note that the B
registers can only be loaded when toggle mode is enabled. The
sequence of events when configuring the AD5383 for toggle
mode is
1.
2.
3.
4.
Enable toggle mode for the required channels via the
control register.
Load data to A registers.
Load data to B registers.
Apply LDAC .
VOUT31
VOUT0
DAC_GND SIGNAL_GND
REFOUT/REFIN
MON_IN1
MON_IN2
Figure 41. Typical Channel Monitoring Circuit
AD5383
AVCC
AVCC
MON_OUT
Rev. 0 | Page 34 of 40
AGND
SYNC
SCLK
DIN
V
The LDAC is used to switch between the A and B registers in
determining the analog output. The first LDAC configures the
output to reflect data in the A registers. This mode offers signif-
icant advantages if the user wants to generate a square wave at
the output of all 32 channels, as might be required to drive a
liquid crystal based variable optical attenuator. In this case, the
user writes to the control register and enables the toggle func-
tion by setting CR3 to CR2 = 1, thus enabling the four groups of
eight for toggle mode operation. The user must then load data
to all 32 A and B registers. Toggling LDAC sets the output
values to reflect the data in the A and B registers. The LDAC ’s
frequency determines the frequency of the square wave output.
Toggle mode is disabled via the control register. The first LDAC
following the disabling of the toggle mode updates the outputs
with the data contained in the A registers.
THERMAL MONITOR FUNCTION
The AD5383 contains a temperature shutdown function to
protect the chip in case multiple outputs are shorted. The short
circuit current of each output amplifier is typically 40 mA.
Operating the AD5383 at 5 V leads to a power dissipation of
200 mW per shorted amplifier. With five channels shorted, this
leads to an extra watt of power dissipation. For the 100-lead
LQFP, the θ
The thermal monitor is enabled by the user via CR6 in the
control register. The output amplifiers on the AD5383 are
automatically powered down if the die temperature exceeds
approximately 130°C. After a thermal shutdown has occurred,
the user can re-enable the part by executing a soft power-up if
the temperature has dropped below 130°C or by turning off the
thermal monitor function via the control register.
IN
AD7476
AVCC
GND
SDATA
SCLK
CS
JA
is typically 44°C/W.
CONTROLLER
OUTPUT PORT
INPUT PORT