STC12LE5604 datasheet(30/377 Pages) STC

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Chapter 2. Clock, Power Management and Reset

2.1 Clock

STC12C5620AD series is STC 1T MCU whose system clock is compatible with traditional 8051 MCU.

There are two clock sources available for STC12C5620AD. One is the clock from crystal oscillator and the

other is from internal simple RC oscillator. The internal built-in RC oscillator can be used to replace the external

crystal oscillator in the application which doesn't need an exact system clock. On-chip R/C clock is selected first

in STC-ISP Writer/Programmer because the manufacturer's selection is on-chip R/C clock for STC12C5604AD,

STC12C5608AD, STC12C5612AD, etc. But for STC12C5616AD, STC12C5620AD, STC12C5624AD,

STC12C5628AD, STC12C5630AD and so on, External crystal/clock is selected first in STC-ISP Writer/

Programmer because the manufacturer's selection is external crystal/clock.

To enable the built-in oscillator, user should enable the option "On-Chip R/C Clock" by STC-ISP Writer/

Programmer for STC12C5616AD, STC12C5620AD, STC12C5624AD, STC12C5628AD, STC12C5630AD

etc. To enable the external crystal oscillator, user should enable the option "External Crystal/Clock" by STC-ISP

Writer/Programmer for STC12C5604AD, STC12C5608AD, STC12C5612AD, etc.

2.1.1 On-Chip R/C Clock and External Crystal/Clcok are Optional in STC-ISP.exe

After next-power up/ cold reset

MCU clock can be:

1. On-Chip R/C Clock

2. External Crystal/Clock

STC12LE5604 Datasheet(PDF) 30 Page - STCmicro Technology Co,.Ltd