DAC8562 Datasheet, PDF (13/16 Pages) Analog Devices – +5 Volt, Parallel Input Complete 12-Bit DAC

DAC8562
To compensate for the SSM2018’s gain constant temperature
coefficient of –3300 ppm/°C, a 1 kΩ, temperature-sensitive
resistor (R7) manufactured by the Precision Resistor Com-
pany with a temperature coefficient of +3500 ppm/°C is used.
A C_CON of 1 µF provides a control transition time of 1 ms which
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 kΩ “Compensator” can be
obtained by contacting:
Precision Resistor Company, Incorporated
10601 75th Street North
Largo, FL 34647
[phone]
A High-Compliance, Digitally Controlled Precision Current
Source
The circuit in Figure 38 shows the DAC8562 controlling a
high-compliance, precision current source using an AMP05 in-
strumentation amplifier. The AMP05’s reference pin becomes
the input, and the “old” inputs now monitor the voltage across a
precision current sense resistor, R_CS. Voltage gain is set to unity,
so the transfer function is given by the following equation:
I_OUT
= ^VIN
R_CS
If R_CS equals 100 Ω, the output current is limited to +10 mA
with a 1 V input. Therefore, each DAC LSB corresponds to
2.4 µA. If a bipolar output current is required, then the circuit
in Figure 33 can be modified to drive the AMP05’s reference
pin with a ± 1 V input signal.
Potentiometer P1 trims the output current to zero with the in-
put at 0 V. Fine gain adjustment can be accomplished by adjust-
ing R1 or R2.
A Digitally Programmable Window Detector
A digitally programmable, upper/lower limit detector using two
DAC8562s is shown in Figure 39. The required upper and
lower limits for the test are loaded into each DAC individually
by controlling HDAC/LDAC. If a signal at the test input is not
within the programmed limits, the output will indicate a logic
zero which will turn the red LED on.
R1
100k
R2
5kΩ
+15V
7
17
0.1µF
6
18
12
AMP-05
10
8
1
9
11
2
5
4 _P1
100kΩ
0.1µF
R_CS
100Ω
0mA ≤ I_OUT ≤ 10mA
2.4µA/ LSB
+15V
0.1µF
–15V
2
REF-02 6
0.1µF
4
20
CE 16
CLR ^{15 DAC-8562}
R3
3k
13
R4
DATA
1k
DGND AGND
10
12
Figure 38. A High-Compliance, Digitally Controlled
Precision Current Source
+5V
1kΩ
2
1/6
74HC05
1
+5V
0.1µF
20
16
15
DAC-8562
13
DGND AGND
10 12
+5V
0.1µF
HDAC/LDAC
CLR
DATA
20
16
15
DAC-8562
13
DGND AGND
10 12
V_IN
+5V
+5V
+5V
0.1µF
R1
604Ω
R2
604Ω
3
5
C1
2
4
7
C2
1
6
12
RED LED
T1
PASS/FAIL
GREEN LED
T1
3
4
1/6
74HC05
C1, C2 = 1/4 CMP-404
Figure 39. A Digitally Programmable Window Detector
REV. A
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