D828 Series
Digital Tuning &
Control Characteristics
8-Bit Programmable Filters
Pin-Out Key
Digital Tuning Characteristics
IN
Analog Input Signal
D7 Tuning Bit 7 (MSB)
D6 Tuning Bit 6
The digital tuning interface circuits are a parallel set of eight
(8) 4053 CMOS switches which accept CMOS compatible
inputs for the eight tuning bits (D0 - D7).
OUT Analog Output Signal
GND Power and Signal Return
+Vs Supply Voltage, Positive
-Vs Supply Voltage, Negative
D5 Tuning Bit 5
D4 Tuning Bit 4
Filter tuning follows the tuning equation given below:
D3 Tuning Bit 3
fc = ( fmax/256 ) [ 1 + D7 x 27 + D6 x 26 + D5 x 25 + D4 x 24 +
D3 x 23 + D2 x 22 + D1 x 21 + D0 x 20 ]
Os
Offset Adjustment
D2 Tuning Bit 2
D1 Tuning Bit 1
D0 Tuning Bit 0 (LSB)
where D1 - D7 = "0" or "1", and
OUT
+Vs -Vs
fmax = Maximum tuning frequency;
fc = corner frequency;
Minimum tunable frequency = fmax/256 (D0 thru D7 = 0);
Minimum frequency step (Resolution) = fmax/256
D7
D6
D5
D4
GND
D3
D2
D1
D0
Data Input Specifications
2.00
Input Data Levels
(CMOS Logic)
Input Voltage (Vs = 15 Vdc)
Low Level In
High Level In
0 Vdc min.
11 Vdc min.
4 Vdc max.
15 Vdc max.
+IN-IN Os4
Input Current
High Level In
Low Level In
- 10 -5 µA typ.
+10 -5 µA typ.
-1 µA max..
+1 µA max.
MSB ---
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LSB
Bit
Weight
Input Capacitance
Input Data Format
Positive Logic
5 pF typ
7.5 pF max.
27
26
25
24
23
22
21
20
fc
Frequency Select Bits
Corner
Frequency
D7
D6
D5
D4
D3
D2
D1
D0
Logic "1" = +Vs
Logic "0" = Gnd
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
1
1
1
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
1
0
0
0
1
1
1
1
1
1
0
0
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
fmax/256
fmax/128
fmax/64
fmax/32
fmax/16
fmax/8
Bit Weighting
D0
D7
(Binary-Coded)
LSB (least significant bit)
MSB (most significant bit)
Frequency Range
256 : 1, Binary Weighted
fmax/4
fmax/2
fmax
2
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