ST7263-EMU2 STMicroelectronics, ST7263-EMU2 Datasheet - Page 17

• Manufacturer Part Number: ST7263-EMU2
• Description: MCU, MPU & DSP Development Tools ST7 Emulator Board
• Manufacturer: STMicroelectronics

Specifications of ST7263-EMU2

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3 CLOCKS AND RESET
3.1 CLOCK SYSTEM
3.1.1 General Description
The MCU accepts either a Crystal or Ceramic res-
onator, or an external clock signal to drive the in-
ternal oscillator. The internal clock (f
rived from the external oscillator frequency (f
which is divided by 3 (and by 2 or 4 for USB, de-
pending on the external clock used).
By setting the CLKDIV bit in the Miscellaneous
Register, a 12 MHz external clock can be used giv-
ing an internal frequency of 4 MHz while maintain-
ing a 6 MHz for USB (refer to
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 or ceramic res-
onator in the frequency range specified for f
The circuit shown in
when using a crystal, and
Values for 24 MHz Crystal Resonator
ommended capacitance. The crystal and associat-
ed components should be mounted as close as
possible to the input pins in order to minimize out-
put distortion and start-up stabilisation time.
Table 5. Recommended Values for 24 MHz
Crystal Resonator
Note: R
crystal (see crystal specification).
3.1.2 External Clock
An external clock may be applied to the OSCIN in-
put with the OSCOUT pin not connected, as
shown on
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).
C
C
R
OSCOUT
OSCIN
SMAX
R
P
SMAX
Figure
is the equivalent serial resistor of the
1-10 M
56pF
56pF
20
8. The t
Figure 9
OXOV
Table 5 Recommended
1-10 M
CPU
47pF
47pF
25
Figure
specifications does
) is also routed to
is recommended
OXOV
10).
lists the rec-
CPU
1-10 M
(see Sec-
22pF
22pF
70
) is de-
OSC
osc
),
.
Figure 8. External Clock Source Connections
Figure 9. Crystal/Ceramic Resonator
Figure 10. Clock block diagram
12 MHz
Crystal
24 or
C
OSCIN
%2
OSCIN
EXTERNAL
CLOCK
OSCIN
R
%3
CLKDIV
P
1
0
OSCOUT
OSCOUT
NC
%2
%2
C
OSCOUT
8 or 4 MHz
CPU and
peripherals)
6 MHz (USB)
ST7263
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