 |
|||||||
|
|||||||
|
|
|||||||
|
|||||||
|
|
| M5297P资料 | |
|
M5297P PDF Download |
|
File Size : 116 KB
Manufacturer:MIT Description: The lock detect circuit uses the up and down correction pulses from the phase detector to determine whether the loop is in or out of lock. When the loop is locked, both up and down pulses are very narrow compared to the reference frequency, but the pulse width in the out of lock condition continuously varies, depending on the phase difference between the outputs of the reference and RF counters. The logical AND of the up and down pulses is used to switch a 20mA current sink to pin 18 and a 50k resistor provides a load to VCC. The circuit is shown in Fig. 7c. When lock is established, the narrow pulses from the phase detector ensure that the current source is off for the majority of the time and so pin 18 will be pulled high by the 50k resistor. A voltage comparator with a switching threshold at about 4.7V monitors the voltage at pin 18 and switches pin 17 low when pin 18 is more positive than the 4.7V threshold. When the loop is unlocked, the frequency difference at the counter outputs will produce a cyclic change in pulse width from the phase detector outputs with a frequency equal to the difference in frequency at the reference and RF counter outputs. A small capacitor connected to pin 18 prevents the indication of false phase lock conditions at pin 17 for momentary phase coincidence. Because of the variable width pulse nature of the signal at pin 18 the calculation of a suitable capacitor value is complex, but if an indication with a delay amounting to several times the expected lock up time is acceptable, the delay will be approximately equal to the time constant of the capacitor on pin 18 and the internal 50k resistor. If a faster indication is required, comparable with the loop lock up time, the capacitor will need to be 2C3 times smaller than the time constant calculation suggests. The time to respond to an out of lock condition is 2C3 times less than that required to indicate lock. |
|
| 相关型号 | |
| ◆ AT24C02C-SSHM | |
| ◆ TPS22959DNYR | |
| ◆ ZR431F01TA | |
| ◆ ZMM55C5V6 | |
| ◆ ZJY-4P | |
| ◆ Z9023106PSC | |
| ◆ Z86L8108SSCR535HTR | |
| ◆ Z86E0812PSC | |
| ◆ Z86319 | |
| ◆ Z8623012SSC | |
| 1PCS | 100PCS | 1K | 10K | ||
| 价 格 | |||||
|
型 号：M5297P 厂 家：MIT 封 装：DIP 批 号：06+ 数 量：430 说 明：全新原装正品,优势库存热卖中! |
|||||
|
运 费： 所在地： 新旧程度： |
|||||
| 联系人：林小姐 |
| 电 话：086-755-23815997 |
| 手 机：13632589437 |
| QQ：1097182423,2851921558 |
| MSN： |
| 传 真：0755-23815984 |
| EMail：joylin@hongbotong.com |
| 公司地址： 深圳市福田区深南中路3006号佳和大厦B座2007室 |
