ST62E32BF1 STMicroelectronics, ST62E32BF1 Datasheet - Page 19

• Manufacturer Part Number: ST62E32BF1
• Description: 8-bit Microcontrollers - MCU UV EPROM 8K SPI/UART
• Manufacturer: STMicroelectronics

Specifications of ST62E32BF1

• Product Category: 8-bit Microcontrollers - MCU
• Core: ST6
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 8 MHz
• Program Memory Size: 7948 B
• Data Ram Size: 192 B
• On-chip Adc: Yes
• Package / Case: SDIP-42
• Mounting Style: Through Hole
• A/d Bit Size: 8 bit
• A/d Channels Available: 21
• Data Rom Size: 128 B
• Interface Type: SPI, UART
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Number Of Programmable I/os: 30
• Number Of Timers: 1 x 8 bit
• Program Memory Type: EPROM
• Factory Pack Quantity: 13
• Supply Voltage - Max: 5 V
• Supply Voltage - Min: 4.5 V

CLOCK SYSTEM (Cont’d)
Turning on the main oscillator is achieved by re-
setting the OSCOFF bit of the OSCR Register or
by resetting the MCU. Restarting the main oscilla-
tor implies a delay comprising the oscillator start
up delay period plus the duration of the software
instruction at f
3.1.2 Low Frequency Auxiliary Oscillator
The Low Frequency Auxiliary Oscillator has three
main purposes. Firstly, it can be used to reduce
power consumption in non timing critical routines.
Secondly, it offers a fully integrated system clock,
without any external components. Lastly, it acts as
a safety oscillator in case of main oscillator failure.
This oscillator is available when the OSG ENA-
BLED option is selected. In this case, it automati-
cally starts one of its periods after the first missing
edge from the main oscillator, whatever the reason
(main oscillator defective, no clock circuitry provid-
ed, main oscillator switched off...).
User code, normal interrupts, WAIT and STOP in-
structions, are processed as normal, at the re-
duced f
cy is decreased, since the internal frequency is be-
low 1MHz.
At power on, the Low Frequency Auxiliary Oscilla-
tor starts faster than the Main Oscillator. It there-
fore feeds the on-chip counter generating the POR
delay until the Main Oscillator runs.
The Low Frequency Auxiliary Oscillator is auto-
matically switched off as soon as the main oscilla-
tor starts.
OSCR
Address: 0DBh — Read/Write
Bit 7-1= These bits are not used and must be kept
cleared after reset.
Bit 0 = OSCOFF. Main oscillator turn-off. When
low, this bit enables main oscillator to run. The
main oscillator is switched off when OSCOFF is
high.
7
-
(LFAO)
LFAO
-
frequency. The A/D converter accura-
LFAO
-
clock frequency.
-
-
-
-
OSC
OFF
0
3.1.3 Oscillator Safe Guard
The Oscillator Safe Guard (OSG) affords drastical-
ly increased operational integrity in ST62xx devic-
es. The OSG circuit provides three basic func-
tions: it filters spikes from the oscillator lines which
would result in over frequency to the ST62 CPU; it
gives access to the Low Frequency Auxiliary Os-
cillator (LFAO), used to ensure minimum process-
ing in case of main oscillator failure, to offer re-
duced power consumption or to provide a fixed fre-
quency low cost oscillator; finally, it automatically
limits the internal clock frequency as a function of
supply voltage, in order to ensure correct opera-
tion even if the power supply should drop.
The OSG is enabled or disabled by choosing the
relevant OSG option. It may be viewed as a filter
whose cross-over frequency is device dependent.
Spikes on the oscillator lines result in an effectively
increased internal clock frequency. In the absence
of an OSG circuit, this may lead to an over fre-
quency for a given power supply voltage. The
OSG filters out such spikes (as illustrated in
ure
maximum internal clock frequency, f
to f
relationship is illustrated in
When the OSG is enabled, the Low Frequency
Auxiliary Oscillator may be accessed. This oscilla-
tor starts operating after the first missing edge of
the main oscillator (see
Over-frequency, at a given power supply level, is
seen by the OSG as spikes; it therefore filters out
some cycles in order that the internal clock fre-
quency of the device is kept within the range the
particular device can stand (depending on V
and below f
cy with OSG enabled.
Note. The OSG should be used wherever possible
as it provides maximum safety. Care must be tak-
en, however, as it can increase power consump-
tion and reduce the maximum operating frequency
to f
OSG
OSG
10). In all cases, when the OSG is active, the
.
, which is supply voltage dependent. This
OSG
: the maximum authorised frequen-
ST62T32B ST62E32B
Figure
Figure
11).
13.
INT
, is limited
19/83
DD
Fig-
),