Book Analog Interfacing to Embedded Microprocessors
Figure 6.14
Multiple series LEDs.
Solenoids, Relays, and Other Analog Outputs 155
Figure 6.15
Multiple multiplexed LEDs.
The output of the AD7801 can swing from ground to the positive rail. The
reference for the device can be either the positive supply or an external ref-
erence voltage. The output can source or sink several milliamps.
Like ADCs, DACs are available with both parallel and serial interfaces. The
Analog Devices AD5300 is an 8-bit DAC with a rail-to-rail output and an SPI-
compatible interface. Like the AD7801, the AD5300 can operate with supply
voltages from 2.7 to 5.5 volts.
Specialized DACs
DACs designed for special applications are also available. The Analog Devices
ADV7120 is a triple 8-bit video DAC designed for video use. The part contains
3 DACs for the RGB (red green blue) video signals. The ADV7120 also has
SYNC and BLANK inputs that force all three outputs to the sync and blank-
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