JPS6421532U - - Google Patents
Info
- Publication number
- JPS6421532U JPS6421532U JP11538787U JP11538787U JPS6421532U JP S6421532 U JPS6421532 U JP S6421532U JP 11538787 U JP11538787 U JP 11538787U JP 11538787 U JP11538787 U JP 11538787U JP S6421532 U JPS6421532 U JP S6421532U
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- clock
- phase
- frequency division
- internal clock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000001360 synchronised effect Effects 0.000 claims description 5
- 238000001514 detection method Methods 0.000 claims description 3
- 238000011084 recovery Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 1
Landscapes
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
- Use Of Switch Circuits For Exchanges And Methods Of Control Of Multiplex Exchanges (AREA)
Description
第１図は本考案に係る同期回路の一実施例を示
すブロツク図、第２図は本考案に係る同期回路の
各部において扱われるそれぞれの信号の一例を示
すタイミングチヤート、第３図は従来の同期回路
の構成を示すブロツク図である。
１……デユーテイ変換回路、２……位相比較器
、３，９……分周カウンタ、４……ループフイル
タ、５……電圧制御水晶発振器（ＶＣＸＯ）、６
……クロツクダウン検出回路、７，８……フリツ
プフロツプ、Ｓ１……外部クロツク、Ｓ２……デ
ユーテイ変換出力信号、Ｓ３，Ｓ９……内部クロ
ツク、Ｓ４……分周出力信号、Ｓ５……クロツク
ダウン検出出力信号、Ｓ６……カウンタリセツト
信号、Ｓ７……高速クロツク、Ｓ８……フリツプ
フロツプリセツト信号。
FIG. 1 is a block diagram showing one embodiment of the synchronous circuit according to the present invention, FIG. 2 is a timing chart showing an example of each signal handled in each part of the synchronous circuit according to the present invention, and FIG. 3 is a conventional synchronous circuit. FIG. 2 is a block diagram showing the configuration of a synchronous circuit. 1... Duty conversion circuit, 2... Phase comparator, 3, 9... Frequency division counter, 4... Loop filter, 5... Voltage controlled crystal oscillator (VCXO), 6
...Clockdown detection circuit, 7,8...Flip-flop, S1 ...External clock, S2 ...Duty conversion output signal, S3 , S9 ...Internal clock, S4 ...Frequency division output signal, S5 ...Clockdown detection output signal, S6 ...Counter reset signal, S7 ...High speed clock, S8 ...Flip-flop preset signal.
Claims (1)
カウンタの出力と、システム外から与えられる外
部クロツクとの位相を比較し、該位相差を解消す
べく前記内部クロツクの周波数を制御することに
より該内部クロツクを前記外部クロツクに位相同
期させる位相同期ループと、 前記外部クロツクの入力の中断および復活を検
出するクロツクダウン検出手段と、 該クロツクダウン検出手段により前記外部クロ
ツクの入力の復活が検出されたタイミングから前
記分周カウンタの出力の周期より充分短い時間の
間だけ当該分周カウンタの動作をリセツトする分
周カウンタリセツト制御手段と、 を具備することを特徴とする同期回路。[Claims for Utility Model Registration] The output of a frequency dividing counter that divides the frequency of the internal clock handled within the system is compared with the phase of an external clock provided from outside the system, and in order to eliminate the phase difference, the internal clock is a phase-locked loop for phase-synchronizing the internal clock with the external clock by controlling the frequency; clock-down detection means for detecting interruption and restoration of the input of the external clock; A synchronous circuit characterized by comprising: frequency division counter reset control means for resetting the operation of the frequency division counter for a period sufficiently shorter than the period of the output of the frequency division counter from the timing at which recovery is detected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11538787U JPS6421532U (en) | 1987-07-28 | 1987-07-28 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11538787U JPS6421532U (en) | 1987-07-28 | 1987-07-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6421532U true JPS6421532U (en) | 1989-02-02 |
Family
ID=31356999
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11538787U Pending JPS6421532U (en) | 1987-07-28 | 1987-07-28 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6421532U (en) |
-
1987
- 1987-07-28 JP JP11538787U patent/JPS6421532U/ja active Pending
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