L6472 STMICROELECTRONICS [STMicroelectronics], L6472 Datasheet - Page 27

• Manufacturer Part Number: L6472
• Description: dSPIN fully integrated microstepping motor driver
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L6472
6.8
6.8.1
6.8.2
Internal oscillator and oscillator driver
The control logic clock can be supplied by the internal 16-MHz oscillator, an external
oscillator (crystal or ceramic resonator) or a direct clock signal.
These working modes can be selected by the EXT_CLK and OSC_SEL parameters in the
CONFIG register (see
At power-up the device starts using the internal oscillator and provides a 2-MHz clock signal
on the OSCOUT pin.
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
the OSC_SEL value); otherwise it is unused (see
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
must be placed as close as possible to the pins. Refer to
capacitor value according to the external oscillator frequency.
Table 8.
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
Attention: In any case, before changing clock source configuration, a
Crystal/resonator freq.
CL values according to external oscillator frequency
16 MHz
24 MHz
32 MHz
8 MHz
hardware reset is mandatory. Switching to different clock
configurations during operation could cause unexpected
behavior.
Table
24).
Doc ID 022729 Rev 1
(1)
Figure
12). The crystal/resonator and load capacitors (CL)
Figure
Figure
12).
25 pF (ESR
18 pF (ESR
15 pF (ESR
10 pF (ESR
12).
Table 8
CL
for the choice of the load
max
max
max
max
Functional description
(2)
= 80 Ω)
= 50 Ω)
= 40 Ω)
= 40 Ω)
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