AT89S2051 데이터 시트보기 (PDF) - Atmel Corporation

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AT89S2051

8-bit Microcontroller with 2K/4K Bytes Flash

Atmel Corporation 

4.5 RST

4.6 XTAL1

4.7 XTAL2

Reset input. Holding the RST pin high for two machine cycles while the is running resets the

device.

Each machine cycle takes 6 or clock cycles.

Input to the inverting amplifier and input to the internal clock operating circuit.

Output from the inverting amplifier.

5. Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be

configured for use as an on-chip , as shown in Figure 5-1. Either a quartz crystal or ceramic res-

onator may be used. To drive the device from an external clock source, XTAL2 should be left

unconnected while XTAL1 is driven as shown in Figure 5-2. There are no requirements on the

duty cycle of the external clock signal, since the input to the internal clocking circuitry is through

a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications

must be observed.

Figure 5-1. Connections

Note: C1, C2 = 30 pF ± 10 pF for Crystals

= 40 pF ± 10 pF for Ceramic Resonators

Figure 5-2. External Clock Drive Configuration

4 AT89S2051/S4051

3390C–MICRO–7/05

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