AD7545UE データシートの表示（PDF） - Analog Devices
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AD7545UE Datasheet PDF : 9 Pages
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AD7545
VDD = +10V TO +15V
18
20
C1
33pF
R5
20kΩ
VDD
RFB
+2V
R1
19 VREF AD7545
OUT1 1
10KΩ
AGND 2
MSB DB10–DB0 DGND
4
3
R3
10kΩ
A1
AD544L
+5V
R6
VDD
5kΩ
A2
VO
AD544J
R2
21
R4
2kΩ
33.3kΩ
AD584J 8
4
Figure 12 shows an alternative approach for use with 8-bit
processors which have a full 16-bit wide address bus such as
6800, 8080, Z80 This technique uses the 12 lower address lines
of the processor address bus to supply data to the DAC, thus
each AD7545 connected in this way uses 4k bytes of address
locations. Data is written to the DAC using a single memory
write instruction. The address field of the instruction is orga-
nized so that the lower 12 bits contain the data for the DAC and
the upper 4 bits contain the address of the 4k block at which the
DAC resides.
CMOS DATA BUS
VDD = +10V TO +15V
Figure 10. Single Supply “Bipolar” Twos Complement
D/A Converter
MICROPROCESSOR INTERFACING OF THE AD7545
The AD7545 can directly interface to both 8- and 16-bit micro-
processors via its 12-bit wide data latch using standard CS and
WR control signals.
A typical interface circuit for an 8-bit processor is shown in
Figure 11. This arrangement uses two memory addresses, one
for the lower eight bits of data to the DAC and one for the up-
per four bits of data into the DAC via the latch.
A15
A0
CPU
WR
4
ADDRESS
DECODE
Q0
16-BIT ADDRESS BUS
DB11
12
DB0
CS
AD7545
WR
D7
DATA BUS
D0
Figure 12. Connecting the AD7545 to 8-Bit Processors via
the Address Bus
A15
A0
CPU
WR
ADDRESS BUS
Q0*
CS
ADDRESS
DECODE Q1* CS
LATCH
DB11
4
4
WR
DB8
WR
DB7
8
DB0
AD7545
SUPPLEMENTAL APPLICATION MATERIAL
For further information on CMOS multiplying D/A converters
the reader is referred to the following texts:
Application Guide to CMOS Multiplying D/A converters
available from Analog Devices, Publication Number G479.
Gain Error and Gain Temperature Coefficient of CMOS
Multiplying DACS—Application Note, Publication Number
E630–10–6/81 available from Analog Devices.
D7
8-BIT DATA BUS
8
D0
* Q0 = DECODED ADDRESS FOR DAC
Q1 = DECODED ADDRESS FOR LATCH
Figure 11. 8-Bit Processor to AD7545 Interface
REV. A
–7–
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