ST72262G2 STMicroelectronics, ST72262G2 Datasheet - Page 21

• Manufacturer Part Number: ST72262G2
• Description: 8-BIT MCU WITH FLASH OR ROM MEMORY, ADC, TWO 16-BIT TIMERS, I2C, SPI, SCI INTERFACES
• Manufacturer: STMicroelectronics

Specifications of ST72262G2

• 4 K Or 8 Kbytes Program Memory: ROM or single voltage extended Flash (XFlash) with read-out protection, write protection, In-Circuit Programming and In-Application Programming (ICP and IAP). 10K write/erase cycles guaranteed, data retention
• Clock Sources: crystal/ceramic resonator oscillators, internal RC oscillator and bypass for external clock
• 4 Power Saving Modes: Halt, Active Halt,Wait and Slow
• Two 16-bit Timers With: 2 input captures, 2 output compares, external clock input on one timer, PWM and Pulse generator modes

6.2 MULTI-OSCILLATOR (MO)
The main clock of the ST7 can be generated by
four different source types coming from the multi-
oscillator block:
■
■
■
Each oscillator is optimized for a given frequency
range in terms of consumption and is selectable
through the option byte. The associated hardware
configurations are shown in
electrical characteristics section for more details.
Caution: The OSC1 and/or OSC2 pins must not
be left unconnected. For the purposes of Failure
Mode and Effects Analysis, it should be noted that
if the OSC1 and/or OSC2 pins are left unconnect-
ed, the ST7 main oscillator may start and, in this
configuration, could generate an f
quency in excess of the allowed maximum
(>16MHz.), putting the ST7 in an unsafe/unde-
fined state. The product behaviour must therefore
be considered undefined when the OSC pins are
left unconnected.
External Clock Source
In this external clock mode, a clock signal (square,
sinus or triangle) with ~50% duty cycle has to drive
the OSC1 pin while the OSC2 pin is tied to ground.
Crystal/Ceramic Oscillators
This family of oscillators has the advantage of pro-
ducing a very accurate rate on the main clock of
the ST7. The selection within a list of 5 oscillators
with different frequency ranges has to be done by
option byte in order to reduce consumption (refer
to
the frequency ranges). In this mode of the multi-
oscillator, the resonator and the load capacitors
have to be placed as close as possible to the oscil-
lator pins in order to minimize output distortion and
start-up stabilization time. The loading capaci-
tance values must be adjusted according to the
selected oscillator.
These oscillators are not stopped during the
RESET phase to avoid losing time in the oscillator
start-up phase.
an external source
5 crystal or ceramic resonator oscillators
an internal high frequency RC oscillator
Section 15.1 on page 162
Table
for more details on
3. Refer to the
OSC
clock fre-
Internal RC Oscillator
This oscillator allows a low cost solution for the
main clock of the ST7 using only an internal resis-
tor and capacitor. Internal RC oscillator mode has
the drawback of a lower frequency accuracy and
should not be used in applications that require ac-
curate timing.
In this mode, the two oscillator pins have to be tied
to ground.
Related documentation
AN1530: Accurate timebase for low cost ST7 ap-
plications with internal RC.
Table 3. ST7 Clock Sources
ST72260Gx, ST72262Gx, ST72264Gx
C
L1
Hardware Configuration
EXTERNAL
SOURCE
OSC1
OSC1
OSC1
CAPACITORS
LOAD
ST7
ST7
ST7
OSC2
OSC2
OSC2
C
L2
21/172