424 Series
Digital Tuning &
Control Characteristics
4-Bit Programmable Filters
Digital Tuning Characteristics
Pin-Out Key
The digital tuning interface circuits are a parallel set of CMOS
switches which accept CMOS compatible inputs for the four
tuning bits (D 0 - D 3).
IN
Analog Input Signal
D3 Tuning Bit 3 (MSB)
D2 Tuning Bit 2
OUT Analog Output Signal
GND Power and Signal Return D1 Tuning Bit 1
+Vs Supply Voltage, Positive D0 Tuning Bit 0 (LSB)
-Vs Supply Voltage, Negative +5V Logic Power
Binary Tuning Range
MSB
---
---
LSB
Bit
Weight
23
D3
22
D2
21
D1
20
D0
fc - corner
frequency
Os
Offset Adjustment
0
0
0
0
1
0
0
0
1
1
0
0
1
1
1
0
1
1
1
1
fmax/16
f
max/8
0.80"
0.70"
fmax/4
fmax/2
fmax
OUT
D0
Os
+Vs
GND
IN
-Vs
Bottom View
Binary T uning Equation:
fc = (f max/16) [1+ D x 2 3 + D2 x 2 2 + D1 x 2 1 + D0 x 2 0]
D1
+5V
D2
D3
3
0.10"
0.00"
where D 1 - D 3 = “0” or “1”, and
fmax = Maximum tuning frequency
fc = Corner frequency;
Minimum tunable frequency = f max/16 (D 0 thru D3 = 0);
Minimum frequency step (Resolution) = f
/16
max
Data Input Specifications
Input Data Levels
Discrete Frequencies
F
D 0
0
D1
0
D2
0
D3
0
0
0
0
(+5Vdc CMOS Logic)
FB
F1
F2
F3
F4
1
0
0
Input Voltage (Vs=15 Vdc)
1
1
0
Low Level In
High Level In
0 Vdc min.
3.5 Vdc min.
0.5 Vdc max.
5.0 Vdc max.
1
1
1
1
1
1
1
Discrete Tuning Equation:
fc = FB + D0[f0] + D1[f1] + D2[f2] + D3[f3]
f0, f1, f2, f3 are the incremental frequency shifts for the data
bits D0, D1, D2 and D3. They are selected to realize the five
customer specified programming frequencies FB -> F4. Other
programming codes produce valid fc’s between FB and F4.
Input Current
High Level In
Low Level In
-0.4mAtyp.
+0.4mAtyp.
-2.0mAmax.
+2.0mAmax.
Input Capacitance
20 pF typ.
30 pF max.
Input Data Format
Positive Logic
Frequency Select Bits
Logic “1” = (+5Vdc)
Logic “0” = Gnd
Bit Weight
(Binary-Coded)
D0
LSB (least significant bit)
D3
MSB (most significant bit)
Frequency Range16:1 Binary Weighted
2
1784 Chessie Lane, Ottawa, IL 61350 • Tel: 800/252-7074, 815/434-7800 • FAX: 815/434-8176
e-mail: sales@freqdev.com • Web Address: http://www.freqdev.com
FREQUENCYDEVICES [ FREQUENCY DEVICES, INC. ]
