L6470HTR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
L6470HTR
STMicroelectronics
'L6470HTR' PDF : 70 Pages View PDF
Functional description
L6470
6.8.1
6.8.2
Internal oscillator
In this mode the internal oscillator is activated and OSCIN is unused. If the OSCOUT clock
source is enabled, the OSCOUT pin provides a 2, 4, 8 or 16-MHz clock signal (according to
OSC_SEL value); it is otherwise unused (see Figure 11).
External clock source
Two types of external clock source can be selected: crystal/ceramic resonator or direct clock
source. Four programmable clock frequencies are available for each external clock source:
8, 16, 24 and 32 MHz.
When an external crystal/resonator is selected, the OSCIN and OSCOUT pins are used to
drive the crystal/resonator (see Figure 11). The crystal/resonator and load capacitors (CL)
must be placed as close as possible to the pins. Refer to Table 8 for the choice of load
capacitor values according to the external oscillator frequency.
Table 8. CL values according to external oscillator frequency
Crystal/resonator freq. (1)
CL (2)
8 MHz
16 MHz
24 MHz
32 MHz
25 pF (ESRmax = 80 )
18 pF (ESRmax = 50 )
15 pF (ESRmax = 40 )
10 pF (ESRmax = 40 )
1. First harmonic resonance frequency.
2. Lower ESR value allows the driving of greater load capacitors.
If a direct clock source is used, it must be connected to the OSCIN pin and the OSCOUT pin
supplies the inverted OSCIN signal (see Figure 11).
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DocID16737 Rev 7
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