Working in extreme temperatures or at high
voltages in factory process control, distributed
control, and smart transmitter applications
can be tough for 4- to 20-mA current-mode
transmitters and analog I/O systems. Yet four
12- to 16-bit single-channel digital-to-analog
converters (DACs) from Analog Devices can
make those jobs easier.
These DACs integrate user-programmable
current-source or voltage output. This makes
them attractive because it simplifies design
and saves space. The DACs’ appeal also lies
in the fact that they don’t need tedious calibration
to operate at extreme temperatures. They consist of two pairs of 16- or 12-bit chips
with an SPI-bus interface that differ in their
output characteristics.
The 16-bit AD5422 and its pin-compatible
12-bit cousin, the AD5412, operate from a single
12- to 48-V supply or dual ±12- to ±24-V
supplies. Their output configurations are software
selectable from options of 5 V, 10 V, ±5 V,
and ±10 V in voltage mode and 4 to 20 mA,
0 to 20 mA, and 0 to 24 mA in current mode.
All of their output spans include an additional
over-range setting.
The 16-bit AD5420 and 12-bit AD5410
operate in current-source mode only. With a
single 12- to 60-V supply, their output configuration
is software selectable from 4 to 20 mA,
0 to 20 mA, and 0 to 24 mA. Taking the
AD5422 as a representative, the family
achieves an accuracy level of 0.1% total unadjusted
error (TUE) while operating in voltage or
current mode.
The chips include a precision 5-ppm/°C
internal reference and an overtemperature
indicator. Internal fault detection circuitry
provides hardware and software indication
of opens or shorts in cable wiring or remotely
located loads. To sense output voltage, it
includes a buffered voltage output with force
and sense capability that can compensate
for series protection resistors and fieldwiring
resistance.
An on-chip programmable precision output
amplifier allows rail-to-rail output swing. Analog
outputs can drive capacitive loads up to
1 µF and inductive loads up to 1 H. They come
in 24-lead thin-shrink small-outline packages
(TSSOPs) and 40-lead lead-frame chip-scale
packages (LFCSPs).
Sample units are now available. Unit pricing
in quantities of 1000 range from $3.35
to $4.95.
Analog Devices
www.analog.com
