AD5764R Analog Devices, AD5764R Datasheet - Page 27

• Manufacturer Part Number: AD5764R
• Description: Complete Quad, 16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
• Manufacturer: Analog Devices

Specifications of AD5764R

• Resolution (bits): 16bit
• Dac Update Rate: 1MSPS
• Dac Settling Time: 8µs
• Max Pos Supply (v): +16.5V
• Single-supply: No
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

Data Sheet
DESIGN FEATURES
ANALOG OUTPUT CONTROL
In many industrial process control applications, it is vital that
the output voltage be controlled during power-up and during
brownout conditions. When the supply voltages are changing,
the VOUTx pins are clamped to 0 V via a low impedance path.
To prevent the output amp from being shorted to 0 V during
this time, Transmission Gate G1 is also opened (see Figure 42).
These conditions are maintained until the power supplies stabilize
and a valid word is written to the data register. G2 then opens, and
G1 closes. Both transmission gates are also externally controllable
by using the reset in ( RSTIN ) control input. For example, if RSTIN
is driven from a battery supervisor chip, the RSTIN input is driven
low to open G1 and close G2 on power-off or during a brownout.
Conversely, the on-chip voltage detector output ( RSTOUT ) is
also available to the user to control other parts of the system.
The basic transmission gate functionality is shown in Figure 42.
DIGITAL OFFSET AND GAIN CONTROL
The
a ±16 LSB adjust range and 0.125 LSB resolution. The gain register
allows the user to adjust the
The full-scale output can be programmed to achieve full-scale
ranges of ±10 V, ±10.25 V, and ±10.5 V. A fine gain trim is also
available.
PROGRAMMABLE SHORT-CIRCUIT PROTECTION
The short-circuit current (I
grammed by inserting an external resistor between the ISCC
pin and the PGND pin. The programmable range for the current
is 500 µA to 10 mA, corresponding to a resistor range of 120 kΩ
to 6 kΩ. The resistor value is calculated as follows:
AD5764R
R ≈
I
60
SC
CONTROL
VOLTAGE
MONITOR
AND
Figure 42. Analog Output Control Circuitry
incorporates a digital offset adjust function with
RSTOUT
SC
) of the output amplifiers can be pro-
AD5764R
G1
G2
RSTIN
full-scale output range.
AGNDA
VOUTA
Rev. D | Page 27 of 32
If the ISCC pin is left unconnected, the short circuit current
limit defaults to 5 mA. It should be noted that limiting the
short-circuit current to a small value can affect the slew rate of
the output when driving into a capacitive load. Therefore, the
value of the short-circuit current that is programmed should
take into account the size of the capacitive load being driven.
DIGITAL I/O PORT
The
bits can be configured independently as inputs or outputs and
can be driven or have their values read back via the serial interface.
The I/O port signals are referenced to DV
configured as outputs, they can be used as control signals to
multiplexers or can be used to control calibration circuitry
elsewhere in the system. When configured as inputs, the logic
signals from limit switches, for example, can be applied to D0
and D1 and can be read back using the digital interface.
DIE TEMPERATURE SENSOR
The on-chip die temperature sensor provides a voltage output
that is linearly proportional to the Celsius temperature scale.
Its nominal output voltage is 1.47 V at +25°C die temperature,
varying at 5 mV/°C, giving a typical output range of 1.175 V to
1.9 V over the full temperature range. Its low output impedance,
and linear output simplify interfacing to temperature control
circuitry and analog-to-digital converters (ADCs). The temper-
ature sensor is provided as more of a convenience than as a precise
feature; it is intended for indicating a die temperature change for
recalibration purposes.
LOCAL GROUND OFFSET ADJUST
The
that, when enabled in the function register, adjusts the DAC
outputs for voltage differences between the individual DAC ground
pins and the REFGND pin, ensuring that the DAC output voltages
are always referenced to the local DAC ground pin. For example,
if the AGNDA pin is at +5 mV with respect to the REFGND pin,
and VOUTA is measured with respect to AGNDA, a −5 mV error
results, enabling the local ground offset adjust feature to adjust
VOUTA by +5 mV, thereby eliminating the error.
AD5764R
AD5764R
contains a 2-bit digital I/O port (D1 and D0). These
incorporates a local ground offset adjust feature
CC
and DGND. When
AD5764R