W78L516A 查看數據表（PDF） - Winbond

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W78L516A

8-BIT MICROCONTROLLER

Winbond 

W78LE516/W78L516A

5.3 Clock

The W78L516 is designed with either a crystal oscillator or an external clock. Internally, the clock is

divided by two before it is used by default. This makes the W78L516 relatively insensitive to duty

cycle variations in the clock.

5.4 Crystal Oscillator

The W78L516 incorporates a built-in crystal oscillator. To make the oscillator work, a crystal must be

connected across pins XTAL1 and XTAL2. In addition, a load capacitor must be connected from each

pin to ground.

5.5 External Clock

An external clock should be connected to pin XTAL1. Pin XTAL2 should be left unconnected. The

XTAL1 input is a CMOS-type input, as required by the crystal oscillator.

5.6 Power Management

Idle Mode

Setting the IDL bit in the PCON register enters the idle mode. In the idle mode, the internal clock to

the processor is stopped. The peripherals and the interrupt logic continue to be clocked. The

processor will exit idle mode when either an interrupt or a reset occurs.

Power-down Mode

When the PD bit in the PCON register is set, the processor enters the power-down mode. In this

mode all of the clocks are stopped, including the oscillator. To exit from power-down mode is by a

hardware reset or external interrupts INT0 to INT1 when enabled and set to level triggered.

5.7 Reduce EMI Emission

The W78L516 allows user to diminish the gain of on-chip oscillator amplifier by using programmer to

clear the B7 bit of security register. Once B7 is set to 0, a half of gain will be decreased. Care must be

taken if user attempts to diminish the gain of oscillator amplifier, reducing a half of gain may affect the

external crystal operating improperly at high frequency. The value of C1 and C2 may need some

adjustment while running at lower gain.

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