HT46R51-18 データシートの表示（PDF） - Holtek Semiconductor

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HT46R51-18

A/D Type 8-Bit OTP MCU

Holtek Semiconductor 

HT46R51/HT46R52

Application Circuits

V DD

0 .0 1 m F

VDD

100kW

0 .1 m F

RES

10kW

0 .1 m F

VSS

O SC

C ir c u it

S e e R ig h t S id e

O SC1

O SC2

P A 0~P A 2

P A 3 /P F D

P A 4 /T M R

P A 5 /IN T

P A 6~P A 7

P B 0 /A N 0

P B 4 /A N 4

P D 0 /P W M

V DD

470pF

R O SC

fS Y S /4

O SC1

O SC2

C1

O SC1

C2

R1

O SC2

R C S y s te m O s c illa to r

30kW < R OSC< 750kW

C r y s ta l S y s te m O s c illa to r

F o r th e v a lu e s ,

s e e ta b le b e lo w

H T 4 6 R 5 1 /H T 4 6 R 5 2

O S C C ir c u it

The following table shows the C1, C2 and R1 values corresponding to the different crystal values. (For reference only)

Crystal or Resonator

C1, C2

R1

4MHz Crystal

0pF

10kW

4MHz Resonator

10pF

12kW

3.58MHz Crystal

0pF

10kW

3.58MHz Resonator

25pF

10kW

2MHz Crystal & Resonator

25pF

10kW

1MHz Crystal

35pF

27kW

480kHz Resonator

300pF

9.1kW

455kHz Resonator

300pF

10kW

429kHz Resonator

300pF

10kW

The function of the resistor R1 is to ensure that the oscillator will switch off should low voltage conditions occur.

Such a low voltage, as mentioned here, is one which is less than the lowest value of the MCU operating volt-

age. Note however that if the LVR is enabled then R1 can be removed.

Note:

The resistance and capacitance for reset circuit should be designed in such a way as to ensure that the VDD is

stable and remains within a valid operating voltage range before bringing RES to high.

²*² Make the length of the wiring, which is connected to the RES pin as short as possible, to avoid noise

interference.

Rev. 1.40

21

July 12, 2005

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