DAC8512FP Analog Devices Inc, DAC8512FP Datasheet - Page 16

• Manufacturer Part Number: DAC8512FP
• Description: IC DAC 12BIT 5V COMPLETE 8-DIP
• Manufacturer: Analog Devices Inc

Specifications of DAC8512FP

• Mounting Type: Through Hole
• Rohs Status: RoHS non-compliant
• Settling Time: 16µs
• Number Of Bits: 12
• Data Interface: Serial
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 2.5mW
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Resolution (bits): 12bit
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Update Rate: 0.0625MSPS
• No. Of Bits: 12 Bit
• Leaded Process Compatible: No
• Interface Type: Serial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

DAC8512
A Serial DAC, Audio Volume Control
The DAC8512 is well suited to control digitally the gain or at-
tenuation of a voltage controlled amplifier. In professional audio
mixing consoles, music synthesizers, and other audio processors,
VCAs, such as the SSM2018, adjust audio channel gain and at-
tenuation from front panel potentiometers. The VCA provides a
clean gain transition control of the audio level when the slew
rate of the analog input control voltage, V
The circuit in Figure 40 illustrates a volume control application
using the DAC8512 to control the attenuation of the SSM2018.
Since the supply voltage available in these systems is typically
to power the DAC. No trimming of the reference is required be-
cause of the reference’s tight initial tolerance and low supply
current consumption of the DAC8512. The SSM2018 is config-
ured as a unity-gain buffer when its control voltage equals 0
volt. This corresponds to a 000
Since the SSM2018 exhibits a gain constant of –28 mV/dB
(typical), the DAC’s full-scale output voltage has to be scaled
down by R6 and R7 to provide 80 dB of attenuation when the
15 V or 18 V, a REF02 is used to supply the +5 V required
0.1 F
Figure 40. A Serial DAC, Audio Volume Control
OFFSET
+15V
100k
V
REF02
TRIM
IN
+15V
P1
–15V
4
+15V
2
0.1 F
SCLK
18k
CLR
SDI
CS
LD
10M
6
2
6
5
3
4
500k
P2
DAC8512
47pF
+5V
SYMMETRY
TRIM
H
1
7
code from the DAC8512.
1
2
3
4
5
6
7
8
0.1 F
SSM2018
18k
* – PRECISION RESISTOR
PT146
10pF
1k COMPENSATOR
8
C
, is properly chosen.
470k
825
R6
16
15
14
13
12
10
11
9
1k
R7
*
0V
30k
V
C
0.1 F
C
1 F
+2.24V
CON
V
+15V
–15V
OUT
–16–
Hexadecimal Number
in DAC Register
000
400
800
C00
FFF
digital code equals FFF
sponds to 0.02 dB of attenuation. Table IV illustrates the at-
tenuation vs. digital code of the volume control circuit.
To compensate for the SSM2018’s gain constant temperature
coefficient of –3300 ppm/ C, a 1 k , temperature-sensitive re-
sistor (R7) manufactured by the Precision Resistor Company
with a temperature coefficient of +3500 ppm/ C is used. A
C
yields a click-free change in the audio channel attenuation. Sym-
metry and offset trimming details of the VCA can be found in
the SSM2018 data sheet.
Information regarding the PT146 1 k “Compensator” can be
obtained by contacting:
An Isolated, Programmable, 4-20 mA Process Controller
In many process control system, applications, two-wire current
transmitters are used to transmit analog signals through noisy
environments. These current transmitters use a “zero-scale” sig-
nal current of 4 mA that can be used to power the transmitter’s
signal conditioning circuitry. The “full-scale” output signal in
these transmitters is 20 mA. The converse approach to process
control can also be used; a low-power, programmable current
source can be used to control remotely located sensors or de-
vices in the loop.
A circuit that performs this function is illustrated in Figure 41.
Using the DAC8512 as the controller, the circuit provides a
programmable output current of 4 mA to 20 mA, proportional
to the DAC’s digital code. Biasing for the controller is provided
by the REF02 and requires no external trim for two reasons:
(1) the REF02’s tight initial output voltage tolerance and (2) the
low supply current consumption of both the OP90 and the
DAC8512. The entire circuit, including opto-couplers, con-
sumes less than 3 mA from the total budget of 4 mA. The OP90
regulates the output current to satisfy the current summation at
the noninverting node of the OP-90. The KCL equation at
Pin 3 is given by:
CON
Precision Resistor Company, Incorporated
10601 75th Street North
Largo, Fl 34647
[phone]
I
OUT
of 1 F provides a control transition time of 1 ms which
=
Table IV. SSM-2018 VCA Attenuation vs.
DAC8512 Input Code
R7
1
1 mV Digital Code R3
H
. Therefore, every DAC LSB corre-
Control
Voltage (V)
0
+0.56
+1.12
+1.68
+2.24
R1
V
VCA
Attenuation (dB)
0
20
40
60
80
REF
R2
R3
REV. A