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AS3932

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 k

Ω

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

Note:

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.

Table 24. Characteristics of External Clock

Symbol

Parameter

Conditions

Min

Typ

Max

Units

VI

Low level

0

0.1 *

V

Vh

High level

0.9 *

V

Tr

Rise-time

3

µs

Tf

Fall-time

3

µs

T=1/2

πRC

RC Time constant

90

100

110

µs