DAC8562 Analog Devices, DAC8562 Datasheet - Page 12

• Manufacturer Part Number: DAC8562
• Description: +5 Volt, Parallel Input Complete 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of DAC8562

• Resolution (bits): 12bit
• Dac Update Rate: 62.5kSPS
• Dac Settling Time: 16µs
• Max Pos Supply (v): +5.25V
• Single-supply: Yes
• Dac Type: Voltage Out
• Dac Input Format: Par

Alternatively, the output voltage can be coded in complementary
offset binary using the circuit in Figure 35. This configuration
eliminates the need for a pull-down resistor or an op amp for
REFOUT The transfer equation of the circuit is given by:
and, for the values shown, becomes:
Generating a Negative Supply Voltage
Some applications may require bipolar output configuration, but
only have a single power supply rail available. This is very com-
mon in data acquisition systems using microprocessor-based sys-
tems. In these systems, only +12 V, +15 V, and/or +5 V are
available. Shown in Figure 36 is a method of generating a nega-
tive supply voltage using one CD4049, a CMOS hex inverter,
operating on +12 V or +15 V. The circuit is essentially a charge
pump where two of the six are used as an oscillator. For the val-
ues shown, the frequency of oscillation is approximately 3.5 kHz
and is fairly insensitive to supply voltage because R1 > 2
The remaining four inverters are wired in parallel for higher out-
put current. The square-wave output is level translated by C2 to
a negative-going signal, rectified using a pair of 1N4001s, and
then filtered by C3. With the values shown, the charge pump
will provide an output voltage of –5 V for current loading in the
range 0.5 mA I
0.5 mA
Audio Volume Control
The DAC8562 is well suited to control digitally the gain or
attenuation of a voltage controlled amplifiers. In professional
DAC8562
INVERTERS = CD4049
3
R1
510k
V
Figure 35 Bipolar Output Operation Without
Trim Version 2
O
Figure 36. Generating a –5 V Supply When
Only +12 V or +15 V Are Available
I
R3 R4
OUT
2
DAC-8562
–1 mV
R4
V
5
R2
5.1k
0.02µF
O
C1
OUT
7 mA with a +12 V supply.
REFOUT
4
V
OUT
2.44 mV
V
RANGE
±5V
O
Digital Code
10 mA with a +15 V supply and
14
11
1
7
9
R2
R2
23.7k + 715
R1
R3
R1
10
12
15
6
Digital Code 5 V
C2
47µF
R4
R4
13.7k + 169
R2
R1
D1
1N4001
1N4001
R2
R1 = R3 = 10k
D2
REFOUT
C3
47µF
470
R3
1N5231
5.1V
ZENER
V
O
–5V
R2.
–12–
audio mixing consoles, music synthesizers, and other audio proces-
sors, VCAs, such as the SSM2018, adjust audio channel gain and
attenuation 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
cuit in Figure 37 illustrates a volume control application using the
DAC8562 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 DAC8562. 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
digital code equals FFF
sponds to 0.02 dB of attenuation. Table V illustrates the attenu-
ation versus digital code of the volume control circuit.
Hexadecimal Number
in DAC Register
000
400
800
C00
FFF
15 V or 18 V, a REF02 is used to supply the +5 V required
OFFSET
+15V
100k
+15V
V
REF-02
TRIM
IN
P1
–15V
4
+15V
2
0.1µF
Table V. SSM2018 VCA Attenuation vs.
DAC8562 Input Code
CLR
0.1µF
CE
Figure 37. Audio Volume Control
18k
10M
6
DATA
15
16
500k
H
P2
DGND
DAC-8562
. Therefore, every DAC LSB corre-
10
47pF
Control Voltage
(V)
0
+0.56
+1.12
+1.68
+2.24
SYMMETRY
TRIM
+5V
20
AGND
4
1
2
3
5
6
7
8
12
C
0.1µF
H
SSM-2018
, is properly chosen. The cir-
code from the DAC8562.
* – PRECISION RESISTOR PT146
1k COMPENSATOR
10pF
18k
13
470k
825
R6
16
10
15
14
13
12
11
9
1k
VCA Attenuation
(dB)
0
20
40
60
80
R7
*
0V
30k
V
C
0.1µF
C
1µF
+2.24V
CON
V
+15V
–15V
REV. A
OUT