AD7846 Analog Devices, AD7846 Datasheet - Page 17

• Manufacturer Part Number: AD7846
• Description: 16-Bit Voltage Output CMOS DAC
• Manufacturer: Analog Devices

Specifications of AD7846

• Resolution (bits): 16bit
• Dac Update Rate: 143kSPS
• Dac Settling Time: 7µs
• Max Pos Supply (v): +15.75V
• Single-supply: No
• Dac Type: Voltage Out
• Dac Input Format: Par

DIGITAL FEEDTHROUGH
In the preceding interface configurations, most digital inputs to
the AD7846 are directly connected to the microprocessor bus.
Even when the device is not selected, these inputs are constantly
changing. The high frequency logic activity on the bus can feed
through the DAC package capacitance to show up as noise on
the analog output. To minimize this digital feedthrough, isolate
Figure 29. AD7846 Interface Circuit Using Latches to Minimize Digital Feedthrough
*LINEAR CIRCUITRY OMITTED FOR CLARITY
PROCESSOR
A1 TO A15
D0 TO D15
MICRO-
R/W
DATA BUS
ADDRESS BUS
ADDRESS
DECODE
Rev. G | Page 17 of 24
B BUS
DIR
74LS245
the DAC from the noise source. Figure 29 shows an interface
circuit that isolates the DAC from the bus.
Note that to make use of the AD7846 readback feature using
the isolation technique of Figure 29, the latch needs to be
bidirectional.
2×
A BUS
G
+5V
CLR
LDAC
DB0 TO DB15
CS
R/W
AD7846*
AD7846