4-Bit Programmable Filters

428 Series

Digital Tuning &

Control Characteristics

1784 Chessie Lane, Ottawa, IL 61350 • Tel: 800/252-7074, 815/434-7800 • FAX: 815/434-8176

e-mail: sales@freqdev.com •

W eb Address: http://www.freqdev.com

Digital Tuning Characteristics

The digital tuning interface circuits are a parallel set of CMOS

switches which accept CMOS compatible inputs for the four

Binary Tuning Range

Pin-Out Key

IN

Analog Input Signal

Tuning Bit 3 (MSB)

OUT Analog Output Signal

Tuning Bit 2

Tuning Bit 1

Tuning Bit 0 (LSB)

-Vs Supply Voltage, Negative +5V Logic Power

Os

Offset Adjustment

Data Input Specifications

Input Data Levels

(+5Vdc CMOS Logic)

Low Level In

0 Vdc min.

0.5 Vdc max.

High Level In

3.5 Vdc min.

5.0 Vdc max.

Input Current

High Level In

-0.4mAtyp.

-2.0mAmax.

Low Level In

+0.4mAtyp.

+2.0mAmax.

Input Capacitance

20 pF typ.

30 pF max.

Input Data Format

Frequency Select Bits

Positive Logic

Logic “1” = (+5Vdc)

Logic “0” = Gnd

Bit Weight

(Binary-Coded)

LSB (least significant bit)

MSB (most significant bit)

Frequency Range16:1 Binary Weighted

MSB

---

---

LSB

Bit

Weight

fc - corner

frequency

00

0

0

00

0

1

00

1

1

01

1

1

11

1

1

Binary Tuning Equation:

fc = Corner frequency;

Discrete Frequencies

00

0

0

10

0

0

11

0

0

11

1

0

11

1

1

Discrete Tuning Equation:

customer specified programming frequencies F

B

2

Bottom View

0.80"

0.70"

0.10"

0.00"

-Vs

IN

D0

D1

D3

Os

OUT

D2

+5V

GND

+Vs

->