ST7265XEVALMS STMicroelectronics, ST7265XEVALMS Datasheet - Page 27

• Manufacturer Part Number: ST7265XEVALMS
• Manufacturer: STMicroelectronics

Specifications of ST7265XEVALMS

• Lead Free Status / Rohs Status: Supplier Unconfirmed

6 SUPPLY, RESET AND CLOCK MANAGEMENT
6.1 CLOCK SYSTEM
6.1.1 General Description
The MCU accepts either a 12 MHz crystal or an
external clock signal to drive the internal oscillator.
The internal clock (f
nal oscillator frequency (f
Stand-alone mode and 48Mhz in USB mode.
The internal clock (f
ing the CP[1:0] and CPEN bits in the MISCR1 reg-
ister.
In USBV
generating a 48MHz clock to the USB. In this
mode, f
In V
bled, and the maximum frequency of f
MHz.
The internal clock signal (f
the on-chip peripherals. The CPU clock signal
consists of a square wave with a duty cycle of
50%.
The internal oscillator is designed to operate with
an AT-cut parallel resonant quartz in the frequency
range specified for f
ure 16
Table 7
crystal and associated components should be
mounted as close as possible to the input pins in
order to minimize output distortion and start-up
stabilisation time.
Table 7. Recommended Values for 12-MHz
Crystal Resonator
Note: R
crystal (see crystal specification).
C
C
R
OSCOUT
DD
OSCIN
SMAX
is recommended when using a crystal, and
mode the PLL and the USB clock are disa-
CPU
SMAX
lists the recommended capacitance. The
DD
power supply mode, the PLL is active,
can be configured to be up to 8 MHz.
is the equivalent serial resistor of the
56pF
56pF
20 Ω
CPU
CPU
osc
. The circuit shown in
) is software selectable us-
) is derived from the inter-
OSC
CPU
47pF
47pF
25 Ω
), which is 12 Mhz in
) is also routed to
CPU
22pF
22pF
70 Ω
is 6
Fig-
6.1.2 External Clock
An external clock may be applied to the OSCIN in-
put with the OSCOUT pin not connected, as
shown on
does not apply when using an external clock input.
The equivalent specification of the external clock
source should be used instead of t
tion 6.5 CONTROL TIMING).
Figure 15. External Clock Source Connections
Figure 16. Crystal Resonator
C
OSCIN
Figure
OSCIN
EXTERNAL
CLOCK
OSCIN
15. The t
OSCOUT
OSCOUT
OXOV
NC
C
OSCOUT
OXOV
specifications
ST7265x
(see Sec-
27/163
1