424 Series
4-Bit Programmable Filters
Digital Tuning Characteristics
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
).
Digital Tuning &
Control Characteristics
Pin-Out Key
IN
Analog Input Signal
D
3
D
2
D
0
Tuning Bit 3 (MSB)
Tuning Bit 2
Tuning Bit 1
Tuning Bit 0 (LSB)
OUT Analog Output Signal
+Vs
-Vs
Os
Supply Voltage, Positive
Offset Adjustment
0.80"
0.70"
Binary Tuning Range
MSB
2
D
3
0
0
0
0
1
3
GND Power and Signal Return D
1
LSB
2
D
0
0
1
1
1
1
0
---
2
D
2
0
0
0
1
1
2
---
2
D
1
0
0
1
1
1
1
Bit
Weight
fc - corner
frequency
f
max
/16
f
max
/8
f
max
/4
f
max
/2
f
max
Supply Voltage, Negative +5V Logic Power
OUT
Binary T uning Equation:
fc = (f
max
/16) [1+ D
3
x 2
3
+ D
2
x 2
2
+ D
1
x 2
1
+ D
0
x 2
0
]
where D
1
- D
3
= “0” or “1”, and
f
max
= Maximum tuning frequency
fc = Corner frequency;
Minimum tunable frequency = f
max
/16 (D
0
thru D
3
= 0);
Minimum frequency step (Resolution) = f
max
/16
Bottom View
0.10"
0.00"
0.00"
D0
D1
+5V
D2
D3
GND Os
-Vs +Vs
IN
0.30"
0.50"
0.80"
0.90"
1.00"
1.10"
1.30"
1.50"
1.60"
Discrete Frequencies
F
F
B
F
1
F
2
F
3
F
4
D
0
0
1
1
1
1
D
1
0
0
1
1
1
D
2
0
0
0
1
1
D
3
0
0
0
0
1
Data Input Specifications
Input Data Levels
Input Voltage (
Vs=15 Vdc
)
Low Level In
High Level In
Input Current
High Level In
Low Level In
Input Capacitance
Input Data Format
Positive Logic
Bit Weight
D
0
D
3
(+5Vdc CMOS Logic)
0 Vdc min.
3.5 Vdc min.
-0.4mAtyp.
+0.4mAtyp.
20 pF typ.
0.5 Vdc max.
5.0 Vdc max.
-2.0mAmax.
+2.0mAmax.
30 pF max.
Discrete Tuning Equation:
fc = F
B
+ D
0
[f
0
] + D
1
[f
1
] + D
2
[f
2
] + D
3
[f
3
]
f
0
, f
1
, f
2
, f
3
are the incremental frequency shifts for the data
bits D
0
, D
1
,
D
2
and D
3
. They are selected to realize the five
customer specified programming frequencies F
B
-> F
4
. Other
programming codes produce valid fc’s between F
B
and F
4
.
Frequency Select Bits
Logic “1” = (+5Vdc)
Logic “0” = Gnd
(Binary-Coded)
LSB (least significant bit)
MSB (most significant bit)
Frequency Range16:1 Binary Weighted
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
2
1.80"
FREQUENCYDEVICES [ FREQUENCY DEVICES, INC. ]
