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Rev. 1.00
42
October 26, 2018
Rev. 1.00
43
October 26, 2018
BS86DH12C
High Voltage Touch A/D Flash MCU with HVIO
BS86DH12C
High Voltage Touch A/D Flash MCU with HVIO
Prescaler
HIRC
f
H
f
H
/2
f
H
/4
f
H
/8
f
H
/16
f
H
/32
f
H
/64
CKS2~CKS0
f
SYS
LXT
Low Speed
Oscillators
LIRC
FSS
f
LIRC
IDLE0
SLEEP
IDLE2
SLEEP
f
SUB
f
SUB
High Speed
Oscillator
HIRCEN
System Clock Configurations
Internal High Speed RC Oscillator – HIRC
The internal RC oscillator is a fully integrated system oscillator requiring no external components.
The internal RC oscillator has three fixed frequencies of 8MHz, 12MHz and 16MHz, which is
selected using a configuration option. The HIRC1~HIRC0 bits in the HIRCC register must also be
configured to match the selected configuration option frequency. Setting up these bits is necessary to
ensure that the HIRC frequency accuracy specified in the A.C. Characteristics is achieved. Device
trimming during the manufacturing process and the inclusion of internal frequency compensation
circuits are used to ensure that the influence of the power supply voltage, temperature and process
variations on the oscillation frequency are minimised. Note that this internal system clock option
requires no external pins for its operation.
Internal 32kHz Oscillator – LIRC
The Internal 32 kHz System Oscillator is one of the low frequency oscillator choices, which is
selected by the FSS bit in the SCC register. It is a fully integrated RC oscillator with a typical
frequency of 32kHz, requiring no external components for its implementation. Device trimming
during the manufacturing process and the inclusion of internal frequency compensation circuits are
used to ensure that the influence of the power supply voltage, temperature and process variations on
the oscillation frequency are minimised.
External 32.768 kHz Crystal Oscillator – LXT
The External 32.768 kHz Crystal System Oscillator is one of the low frequency oscillator choices,
which is selected by the FSS bit in the SCC register. This clock source has a fixed frequency of
32.768 kHz and requires a 32.768 kHz crystal to be connected between pins XT1 and XT2. The
external resistor and capacitor components connected to the 32.768 kHz crystal are necessary to
provide oscillation. For applications where precise frequencies are essential, these components may
be required to provide frequency compensation due to different crystal manufacturing tolerances.
During power-up there is a time delay associated with the LXT oscillator waiting for it to start-up.
When the microcontroller enters the SLEEP or IDLE Mode, the system clock is switched off to stop
microcontroller activity and to conserve power. However, in many microcontroller applications it
may be necessary to keep the internal timers operational even when the microcontroller is in the
SLEEP or IDLE Mode. To do this, another clock, independent of the system clock, must be provided.