0-57669-B

0-57669-B

电话：（微信同号）/，QQ：1982497648

大量现货，价格合理，当天打款，当天顺丰，即日到货。
1、华东地区（包括山东、江苏、安徽、浙江、福建、上海）； 
2、华南地区（包括广东、广西壮族自治区、海南）； 
3、华中地区（包括湖北、湖南、河南、江西）； 
4、华北地区（包括北京直辖市、天津直辖市、河北、山西、内蒙古自治区）；
5、西北地区（包括宁夏回族自治区、、青海、陕西、甘肃）； 
6、西南地区（包括四川、云南、贵州、西藏自治区、重庆直辖市）； 
7、东北地区（包括辽宁、吉林、黑龙江）； 
8、台港澳地区（包括台湾、香港、澳门）。
 
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概述

微控制器的时钟源可以分为两类：基于机械谐振器件的时钟源，如晶振、陶瓷谐振槽路；基于相移电路的时钟源，如：RC (电阻、电容)振荡器。硅振荡器通常是完全集成的RC振荡器，为了提高稳定性，包含有时钟源、匹配电阻和电容、温度补偿等。图1给出了两种时钟源。图1给出了两个分立的振荡器电路，其中图1a为皮尔斯振荡器配置，用于机械式谐振器件，如晶振和陶瓷谐振槽路。图1b为简单的RC反馈振荡器。

 简单时钟源：(a) 皮尔斯振荡器 (b) RC反馈振荡器
                图1. 简单时钟源：(a) 皮尔斯振荡器 (b) RC反馈振荡器


机械式谐振器与RC振荡器的主要区别

基于晶振与陶瓷谐振槽路(机械式)的振荡器通常能提供非常高的初始精度和较低的温度系数。相对而言，RC振荡器能够快速启动，成本也比较低，但通常在整个温度和工作电源电压范围内精度较差，会在标称输出频率的5%至50%范围内变化。图1所示的电路能产生可靠的时钟信号，但其性能受环境条件和电路元件选择以及振荡器电路布局的影响。需认真对待振荡器电路的元件选择和线路板布局。在使用时，陶瓷谐振槽路和相应的负载电容必须根据特定的逻辑系列进行优化。具有高Q值的晶振对放大器的选择并不敏感，但在过驱动时很容易产生频率漂移(甚至可能损坏)。影响振荡器工作的环境因素有：电磁干扰(EMI)、机械震动与冲击、湿度和温度。这些因素会增大输出频率的变化，增加不稳定性，并且在有些情况下，还会造成振荡器停振。

振荡器模块

上述大部分问题都可以通过使用振荡器模块避免。这些模块自带振荡器、提供低阻方波输出，并且能够在一定条件下保证运行。常用的两种类型是晶振模块和集成硅振荡器。晶振模块提供与分立晶振相同的精度。硅振荡器的精度要比分立RC振荡器高，多数情况下能够提供与陶瓷谐振槽路相当的精度。

功耗

选择振荡器时还需要考虑功耗。分立振荡器的功耗主要由反馈放大器的电源电流以及电路内部的电容值所决定。CMOS放大器功耗与工作频率成正比，可以表示为功率耗散电容值。比如，HC04反相器门电路的功率耗散电容值是90pF。在4MHz、5V电源下工作时，相当于1.8mA的电源电流。再加上20pF的晶振负载电容，整个电源电流为2.2mA。

陶瓷谐振槽路一般具有较大的负载电容，相应地也需要更多的电流。

相比之下，晶振模块一般需要电源电流为10mA至60mA。

硅振荡器的电源电流取决于其类型与功能，范围可以从低频(固定)器件的几个微安到可编程器件的几个毫安。一种低功率的硅振荡器，如MAX7375，工作在4MHz时只需不到2mA的电流。

CP Power supply (CP205)



ROC Power Supply (X7016102)



Browning 3 V-Groove Sheave (3TB74)



Browning Sheave 2 Groove Classical Series - A / B / C /D (2B80SK)



Lucent Definity Telephone (8411D)



Sequent Computer Systems SCSI In/Out Board (1003-62615 A)



Tektronix Waveform Monitor (528A)



TeleProcessing Products Inc. CSU/DSU Digital Termination Unit (TP-501)



3M Easi-Air Inhalation Valve (70-0700-9197-3?)



PSC inc. Mac - Barcode Scanner (GP5385-183842)



Stromberg Time Recorder (225-3L)



Kwan Chiu Radio Mfg. Power Supply &5 VDC 1.65A (54F0270)



DPT ESDI SCSI Controller Card - TA-0142-WYS-D (HA-0117-011-E)



Pamtech RF Load (ULG 1005)



eMachines Nubus Video Card (030-01493)



Focus Information Systems 2 the Max ISDN Internet Modem (FasCom 128)



IBM IBM 3174 2.4 MB 5.25 FDD w/Case YD-802 (25F8398)



ORCKIT Fast Internet Modem (Orfast-R-A-SA-?Br)



Black Box VGA To Video Global (AC333A)



Everex Battery Charger Stand w/Battery - MIS-00278-00 (MIS-00279-00)



Dodge Sheave 3 A9.0 B9.4 - SK (455631)



General Techonolgy Power Supply (HD-244.8-A)



Microscience 66MB 5.25" HH RLL HDD (HH-1060)



Han One Power Supply 78.6 Watt Seko Epson - Vintage (HN-7080)



EG&G ROTRON Tarzan Motor Fan 270002 230 VAC 85 Watts (TN3A3)



ROC Power Supply (PTO-205)



Nexland Broadband Router (ISB Soho)



Hewlett Packard 5 Watt 600 Ohms Attenuator Set (N/A)



Mitel Smart-1 PAV& Programmable Commuications Controller (8350-R01-SDD1X?X)



Tektronix Plug-in Delaying Time Base Module (7B85)



GNP Computers PDSi RJ21/RJ45 Entry Panel (1-503582)



Data Translation Communication Card 16-Bit ISA (10575)



GNP PDSi CPCI 68-Pin SCSI to IDE Transition Board (1-502518)



GNP PDSi 3U cPSB 8&1 Switch (1-503251)



GE I-50-S Single-Phase Watthour Meter with Circle AW 3R Enclosure



IBM AC Adapter (65F0218)



AcBel AT Power Supply - Wang PC350/16s (API-8069B)



Interlan Controller Card (600-0016-AA)



Intermec Wedge Reader without AC Adapter (9570)



Fujitsu 326MB 3.5" IDE HH Hard Drive (M2622T)



Andrew 8221 Fiber Optic Converter (301-0297-01)



American Technology Labs VRT-2



QMS Sorter Unit Stapler Assembly - QMS L30380 (L30380)



Sync Wan Monitoring Probe (S-FRAP)



NCR MCA SCSI Host Adapter (150-0014198)



Cinema Arts Crafts Hollywood, CA Film Tool (FGR-1)



Compaq Graphics PCI Video Card Proliant (27376-001)



ASUS Motherboard for Sony Vaio PCV-RX270DS (TUSL-LV)



Fastcomm Ethernet FRAD Network Terminal (F9200-SS-FNE1-?A1000)



HP ScanJet Automatic Document Feeder - No AC Adapter (C7710A)



Conversion Devices Power Supply pn 175-00136 (SDP 106-3)



Lucent Office Phone Black 20-Line (MLX-20L)



Kondo Motor Fan 100V 2P Electric Powered Air Blower Squirel Fan (FS-093B-1)



Unisys T27-K5 Keyboard Version 1 (3753-0482)



Cherry Keyboard W/ Card Reader G81-7000LPBUS /12 (MY 7000)



Sick Micro Power Supply (PS51 - 1000)



Hewlett Packard HP 250 for 5, 5M, 5N (C3924A)



DataDesk Mac 101E Terminal Keyboard (1069)



National Instruments Digital I/O for the Macintosh II with Manual (320094-01)



Exabyte Autoloader Tape Drive - AS-IS (EZ17-LVD)



TBLO Calibration Load Panel (F817182-1)



Apple Motherboard for Apple Mac SE 800K (820-0176-B)



Heathkit T.V. Alignment Generator - Vintage Collectable (IG-52)



Browning Sheave (AK134X1)



Westinghouse 510C913G01 Single-Phase Watthour Meter with Circle AW Enclosure



Sangamo CL100 Single-Phase Watthour Meter with Circle AW Enclosure



Wintac/Edom Slot 1 Pentium II System Board 1 AGP 4 PCI 3 ISA (W6LXB-0)



Hollywood Film Company 35mm / 16mm Film Syncronizer (COMB)



HP Pattern Generator (3781B)



Aydin Monitor Systems PCM Synchronizer (352)



Browning Sheave (BX100X 1-3/16)



Siecor Cabinet Mounted Interconnect Center (C-MIC-012)



GE I-70-S Single-Phase Watthour Meter with Circle AW 3R Enclosure



Fukuda Electric 300VA 50-60 Hz Transformer 200-220 to 100-110 VAC (H20-103)



Unknown Socket 3 486 Motherboard V10 M.B. 92135 55.433M)



Epson Intel 386 SX Motherboard Y72320100101 AC 0003934 9103G PII-M1 (723-MA)



IBM 8560 10 Mhz System Board (90X7333)



IBM 8550 System Board 10 MHz 90X6866 (90X9161)



Magnetic Magnetic Stirrer - SK-10537 (MS-3)



Fuji Electric 70A 600 Volt AC 3 Pole Circuit Breaker (BU-ESB3070)



Litronic 3.5" Tape Drive (93125)



Toshiba Laptop Keyboard 500CDT & CDS (P000220190)



HP JetDirect Extenal BNC/RJ45 Multi-Protcl Ether (J2382-60003)



Optibreed Test Kits "Turkey" For Alpharma SQA III's - Progen (460112)



Optibreed Test Kits "Bull" For Alpharma SQA IV's - Progeny (460105)



Optibreed Test Kits Chicken For Alpharma SQA III'S - Progeny (460101)



Catel Video FM Modulator (VFMM-2000)



HP JetDirect Extenal BNC/RJ45 Multi-Protcl Ether (J2382B)



Mountain Tape Controller Card (05-30466-02)



Metra Inc Stainless Steel Vacuum Filter w/ QF flange (1010-026)



Swan Sodium Reference Electrode (87-840100)



Fiber-Optic Light Source Flex Cable Ring Mount Black 38" Long (Microscope)



Fiber-Optic Light Source Flex Cable with 8 Light Ring Mount Black (Microscope)



Heath EGA Video Card 8-Bit ISA (150-256-1)



Keithley Board (INTMDB-64)



Cabletron 6 Port Fiber Interface Module (FOMIM-26)



Fuji Electric Earth Leakage Protective Relay 25mm 100mA (BRR19N-02S)



AST AST Advantage Mem Expansion Board (202051)



ABB K10A S283 480Y/277 VAC 10kA 3 Pole Circuit Breaker (S283-K10W)



Maxtor 40MB 3.5 IDE HDD (7040AT)



Helm/Impression 14" Impression 3Plus CRT Monitor (DCM-1458 E)



Netstal Komplett System Card / Board (PEC 110.240.9960)



Rucker & Kolls, Inc. NANO DAS DEV 1 (9741)



Keithley RS-485 Signal Conditioner (M1142)



Netstal Komplett System Card / Board (PIA 110.240.6181a)



Netstal 9451a Komplett System Card / Board (SPV 110.240.9451)



Condenser Products .02 MFD Capacitors 15,000 Volts DC (KMOC 15M002ES)



IBM MCA Token Ring 16/4 Mca Short (74F9321)



IBM MCA Token Ring 4MB Short 25F7540 93F0198A 93F0198B (93F0198)



IBM Enhanced Emulation MCA Short Card (69X6282)



Burkert 2/2-Way Miniature Solenoid for Valve. (0201 A)



Burkert Solenoid Valve Control Head 2/2WAY 24VDC 8W (00120617)



ORA Electronics Tx 806-821 / Rx 851-866Mhz Booster Amplifier (ID3000)



Spectra Physics Memory Module (A3051-010)



Lumberg 8 Port Aktor Sensor Box (ASBSV)



SonicWall Security Firewall (TELE3 TZX)



Black Flex Waveguide (C Band WR-137)



Black 1' Flex waveguide WR-137 C Band 5.85-8.2 GHz (112944-00A)



Duniway stockroom T-075-N



Forcom Technologies 386 Motherboard Vintage (M396F V2.2)



Compaq 8 Port KVM Switch (106-1502-03)



Port Port Portable 24X CD-ROM - w/ PC Card Dongle (NW24XCD)



Apple iMac Logic motherboard 400MHz (820-1131-A)



Leitch Viewgaurd Decoder (VGD-3200E)



HP DC Power supply 0-25 Volt 0-0.4 Amp (6216A)



Dell Core 2 Duo Latitude - For parts only (D630)



Ideal / MBM Kutrimmer 13.75" er Trimmer (Model 1035)



Dhale 533 Professional Guillotine er Cutter 13.375" 30.16.00533



GEM L51B 15" LCD Monitor VGA



Premier Phone System Chassis PBX Telephone (1224/2460)



Hayes External Accura 28800 V.34 & Fax Modem (5337AM)



Western Quartz 48" UV Lamp (48-20015-C)



Wyse 13" Terminal Green - 901237-01 - Lite Screen Burn (WY-55)



IBM 16BIT MFM fixed disk - floppy diskette (61-031099-00)



Browning Sheave (2B5V80)



Browning 2 V-Groove Sheave (2TB74)



Flexable KU Band 12.4 to 18.0 GHz Waveguide 6" Long (WR-62)



Dison 6 Port Manifold on Dison Controller Board (AMC206)



Renaissance GRX Renegade Graphics Card (20-0001 Rev E)



Wang Power Module (7760-R3M3)



Bell & Howell Super D Proval Lens (2 Inch 16mm / F1.4)



Seiko Instruments Thermal Printer Head - new pulls (LTP5446B-C832)



Cisco Catalyst 2950 Series Switch (WS-C2950-12)



Omega Flow Transmitter (FP-5800)

Sun I/O Board 501-4946-01 (5014946)



GNP PDSi 3U cPSB 8FE&2GE Switch (1-503751)



GNP PDSi NODE2U Alarm Card (11)



GNP PDSi cPCI Alarm Card (05)



GNP PDSi NodeXU Power Supply Test Board (1-503854)



GNP PDSi Smart Node Alarm Card (1-503739)



NEC NEAX 2000 IVS Processor Card (CP01)



NEC Digital Line Circuit Card for Neax 2000 IVS (4DLCD)



Dell 250W ATX Power Supply (1E115)



HP JetDirect 300X NO AC ADAPTER (J3263-60001)



Unysis Automatic Cut Sheet Feeder (AP 1337)



Veriflo High Pressure Regulator w/ Pressure Meter (DSG752-S7P2404?)



APC 650 VA UPS Battery Backup (BK650MC)



Calcom External Modem (1442-Ex)



Shinamo Kensi Ltd Asynchronous, bi-directional, electric motor motor (IB-7541F)



PGC 50 Watt Power Supply (PGC-50-K)



Deer 300W ATX Power Supply (DR-300ATX)



Apple Power Supply Mac Quadra 630, PowerMac 6200 & 6300 (614-0037)



Hollywood Film Company 16mm Film Syncronizer (2.16)



Union Carbide Compressed Gas Regulator w/ Gauge (UPD-3-25-580)



Acer ET.1516B.000 LCD Monitor 15" VGA AL1516 Ab Black



Triplett Electronic Volt-ohmmeter (850)



AMD Athlon XP 2400& 2Ghz/133/256/1.?65V (AXDA2400DKV3C)



HP LaserJet 500-sheet Input Printer Tray (Q7817A)



Nachi 6313-2NSE Ball Bearing Sealed Metric 65 ID x 140 OD x 33 wide



IBM IBM External Modem (7861-025)



IBM 10/100 PCI Ethernet Card 91H0460 (21H5460)



Creative Labs Permedia 2 Graphic 3D PCI Card (CT6610)



Practical Peripherals 56K Mini Tower Modem - PM56KFLEX V 100397 (4709US)



Generic 10x 128MB 168 Pin PC100 SDRAM Memory (Bulk)



Afreey 5.25" CD-ROM Drive 45x (CD-1845E/A)



Texas Instruments VATS2 DSP Interface - PCI SCSI Card (10005655)



HP JetDirect Token Ring LAN DB-9 Network Interface (J2555)



TCL MP Tranceiver Modual Dual Port Card (2110-2BDM)



Power Computing Power Computing Apple Upgrade Processor Card (5000-604-02)



Generic Motor Controller of French Origin (Controller)



Simple 16MB Toshiba Laptop Memory Card T1900 PA2014U (STT4600/16)



Bell Atlantic SMD Rom Keys Set of 4 keys for MDT Tester (SMD Rom Keys)



Optibreed Test Kits "Swine" For Alpharma SQA IV's - Progeny (460113)



Nortel / Meridian 500 Line Card (QPC452B)



Hitachi EMI Filter (NF-CEH20)



IBM 207 Power Supply IBM 8560 (90X7385)



Compaq 145W ATE Power Supply (173609-001)



Micropolis 1.0GB 3.5" IDE Hard Drive (4110A)



Maxtor 10.0GB 3.5" IDE Hard Drive (91008D7)



Homaco 48 Port RJ45 Modular Jack Panel (MJP19-6-25CPU-?V)



NCR EDP Equipment (VP10 0100-7101)



Nortel Starplus II Vodavi Telephone (260400-MOE-27F?)