A5191HRT

http://onsemi.com

10

Internal Oscillator Option

The oscillator cell will function with either a 460.8 kHz

crystal or ceramic resonator. A parallel resonant ceramic

resonator can be connected between XIN and XOUT.

Figure 12 illustrates the crystal option for clock generation

using a 460.8 kHz (

±1 % tolerance) parallel resonant crystal

and two tuning capacitors Cx. The actual values of the

capacitors may depend on the recommendations of the

manufacturer of the resonator. Typically, capacitors in the

range of 100 pF to 470 pF are used.

XOUT

XIN

460.8 kHz

Crystal

Oscillator

Figure 12. Crystal Oscillator

External Clock Option

It may be desirable to use an external 460.8 kHz clock as

shown in Figure 13 rather than the internal oscillator. In

addition, the A5191HRT consumes less current when an

external clock is used. Minimum current consumption

occurs with the clock connected to XOUT and XIN

XOUT

XIN

Crystal

Oscillator

460.8 kHz

Figure 13. Oscillator with External Clock

Power On Reset

During start-up the RESETB pin should be kept low until

= 2.5 V to guarantee correct operation of the digital circuitry.

As illustrated in Figure 14 RESETB should be kept low for

VDD

t

RESET pin

Figure 14. Power On Reset Timing