AS3932 Просмотр технического описания (PDF) - austriamicrosystems AG

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AS3932

3D Low Frequency Wakeup Receiver

austriamicrosystems AG 

AS3932

Data Sheet - Detailed Description

8.9.3 External Clock Source

To clock the AS3932 with an external signal the crystal oscillator has to be enabled (R1<1>=1). As shown in the Figure 3 the clock must be

applied on the pin XIN while the pin XOUT must stay floating. The RC time constant has to be 100μs with a tolerance of ±10% (e.g. R=680 kΩ

and C=22pF). In the Table 24 the clock characteristics are summarized.

Table 24. Characteristics of External Clock

Symbol

Parameter

Conditions

Min Typ Max Units

VI

Low level

0

0.1 *

VDD

V

Vh

High level

0.9 *

VDD

VDD

V

Tr

Rise-time

3

µs

Tf

Fall-time

3

µs

T=1/2πRC

RC Time constant

90

100

110

µs

Note: In power down mode the external clock has to be set to VDD.

8.10 Channel Selection in Scanning Mode and ON/OFF Mode

In case only 2 channels are active and one of the Low Power modes is enabled, then the channels 1 and 3 have to be active. If the chip works in

On-Off mode and only one channel is active then the active channel has to be the channel 1.

Both Low Power modes are not allowed to be enabled at the same time.

www.austriamicrosystems.com/AS3932

Revision 1.2

28 - 33

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