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AS1716

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

Figure 13. Application Diagram, minimal requirements

Values of the suggested external components are indicative and need to be characterized for each specific application.

Typical Piezo Sensor:

!

Resistor from 500k

Ω to 1MΩ

!

Capacity from 900nF to 1.5µF

Typical wire equivalent circuit:

!

Capacity to groung from 100pF to 400pF / meter

!

Capacity between wires strongly depends on type of wires (twisted-pair strongly suggested)

!

Resistance is typical 50m

Ω / meter @ 20°C

Layout rules

!

Input Resistors and Capacitors at the inputs should be placed as close as possible to the stonger possible source

of disturbances (i.e. the input connector).

!

The input lines should be kept as short as possible and routed close to each other.

!

The filter capacitor (100nF) on supply should be a ceramic type and placed as close as possible to the chip.

!

VSSA and VDDA lines on PCB should have larger width than other signals to minimize resistance, especially if the

10µF capacitor is not very close to the chip.

!

The output line should be kept as short as possible.

Due to

failure

up to 16V

typical

sensor

1k

1k

-

+

Multiple Feedback LP filter

fc ~23kHz typ.

Gain Control

x0.5, x1, x2, x4

INN

INP

GA

GB

100

Ω

to

1k

OUT

µC

12 Bit AD

50k S/s

NC

VSSA

VDDA

100nF 10µF

V 4.5...5.5V

-

+

-

+

VDDA/2

-

+

VDDA/2

+

-

VDDA

VDDA/2

VDDA/2

VDDA/2

AS1716