A5191HRT AMIS HART™ Modem
4.5 Oscillator
Data Sheet
The A5191HRT requires a 460.8kHz clock signal on OXTL. This can be provided by an external clock or external components may be connected to the
A5191HRT internal oscillator.
4.5.1 Internal Oscillator Option
The oscillator cell will function with either a 460.8kHz crystal or ceramic resonator. A parallel resonant ceramic resonator can be connected between OXTL
and IXTL. Figure 9 illustrates the crystal option for clock generation using a 460.8kHz (±I percent tolerance) parallel resonant crystal and two tuning
capacitors. The actual values of the capacitors may depend on the recommendations of the manufacturer of the resonator. Typically, capacitors in the
range of 100pF to 470pF are used.
4.5.2 External Clock Option
It may be desirable to use an external 460.8kHz clock as shown in Figure 10 rather than the internal oscillator because of the high cost and low availability
of ceramic resonators. In addition, the A5191HRT consumes less current when an external clock is used. Minimum current consumption occurs with the
clock connected to OXTL and IXTL connected to V
SS
.
Figure 9: Crystal Oscillator
Figure 10: Oscillator with External Clock
5.0 Ordering Information
The A5191HRT is available in a 28-pin plastic leaded chip carrier (PLCC) and 32-pin low-profile quad flat pack (LQFP). Use the following part number when
ordering. Contact your local sales representative for more information: www.amis.com/sales.
Table 4: Ordering Codes
Package
32-pin LQFP
28-pin PLCC
32-pin LQFP
28-pin PLCC
Package Type
Standard (non-Pb-free)
Standard (non-Pb-free)
Green/RoHS compliant
Green/RoHS compliant
Part Name
A5191HRTL
A5191HRTP
A5191HRTLg
A5191HRTPg
Ordering Code*
12197-503-XTP
12197-504-XTP
12197-507-XTP
12197-508-XTP
*The part number extension -XTP refers to the device being shipped as tape and reel. The suffix -XTD refers to
shipment in tubes or tray.
AMI Semiconductor - Rev. 2.0, Mar. 05
www.amis.com
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