AD7545LN Analog Devices Inc, AD7545LN Datasheet - Page 7

• Manufacturer Part Number: AD7545LN
• Description: IC DAC 12BIT W/BUFF MULT 20-DIP
• Manufacturer: Analog Devices Inc

Specifications of AD7545LN

• Rohs Status: RoHS non-compliant
• Settling Time: 2µs
• Number Of Bits: 12
• Data Interface: Parallel
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 20-DIP (0.300", 7.62mm)
• Power Dissipation (max): -

D/A
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.
REV. A
Figure 10. Single Supply “Bipolar” Twos Complement
R2
2kΩ
CPU
10KΩ
R1
Figure 11. 8-Bit Processor to AD7545 Interface
Converter
A15
WR
+2V
A0
D7
D0
19
MSB
V
4
REF
V
V
CMOS DATA BUS
DD
ADDRESS
18
DD
DECODE
DB10–DB0
= +10V TO +15V
AD7545
*
Q
Q
R
1
20
0
FB
= DECODED ADDRESS FOR LATCH
= DECODED ADDRESS FOR DAC
DGND
Q
Q
3
AGND
0
1
OUT1
*
*
4
AD584J
8-BIT DATA BUS
ADDRESS BUS
2
CS
LATCH
1
2
4
WR
1
C1
33pF
8
8
V
4
DD
A1
CS
DB11
DB8
WR
DB7
DB0
AD544L
+5V
10kΩ
5kΩ
R3
R6
33.3kΩ
R4
AD7545
20kΩ
V
R5
DD
= +10V TO +15V
A2
AD544J
8
V
O
–7–
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.
Figure 12. Connecting the AD7545 to 8-Bit Processors via
the Address Bus
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.
CPU
A15
WR
A0
D7
D0
ADDRESS
DECODE
Q
0
4
16-BIT ADDRESS BUS
DATA BUS
12
DB11
DB0
CS
WR
AD7545
AD7545