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BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
For oscillator stability and to minimise the effects of noise and crosstalk, it is important to ensure
that the crystal and any associated resistors and capacitors along with interconnecting lines are all
located as close to the MCU as possible.
External LXT Oscillator
LXT Oscillator Low Power Function
The LXT oscillator can function in one of two modes, the Speed-Up Mode and the Low-Power
Mode. The mode selection is executed using the LXTSP bit in the LXTC register.
LXTSP
LXT Operating Mode
0
Low-Powe�
1
Speed-Up
When the LXTSP bit is set to high, the LXT Quick Start Mode will be enabled. In the Speed-Up
Mode the LXT oscillator will power up and stabilise quickly. However, after the LXT oscillator has
fully powered up, it can be placed into the Low-Power Mode by clearing the LXTSP bit to zero and
the oscillator will continue to run but with reduced current consumption. It is important to note that
the LXT operating mode switching must be properly controlled before the LXT oscillator clock is
selected as the system clock source. Once the LXT oscillator clock is selected as the system clock
source using the CKS bit field and FSS bit in the SCC register, the LXT oscillator operating mode
can not be changed.
It should be note that no matter what condition the LXTSP is set to the LXT oscillator will always
function normally. The only difference is that it will take more time to start up if in the Low Power
Mode.
Internal 32kHz Oscillator − LIRC
The Internal 32 kHz System Oscillator is one of the low frequency oscillator choices, which is
selected via a software control bit, FSS. It is a fully integrated RC oscillator with a typical frequency
of 32 kHz at 5V, 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. As a result, at a power supply of 5V and at a temperature of
25˚C degrees, the fixed oscillation frequency of 32 kHz will have a tolerance within 10%.