啟用/禁用-三態(tài)控制輸入
IIL和IIHAp-Note:
當(dāng)邏輯低電平施加到Oscillator的控制輸入時(shí),IIL是流入或流出控制輸入的電流(通常在控制輸入之外);當(dāng)邏輯高電平施加到振蕩器的控制輸入時(shí),IIH是流入或流出控制輸入(通常進(jìn)入控制輸入)的電流.

影響控制輸入電流的兩個(gè)主要因素:
1.IC設(shè)計(jì)和相關(guān)阻抗.
2.在石英晶體振蕩器封裝內(nèi)部添加任何上拉或下拉電阻.
NEL使用兩種不同的控制輸入特性:
1.振蕩器封裝內(nèi)部不使用IC外部的額外電阻.因此,IIL和IIH僅由IC特性定義.對(duì)于CMOS輸入,這通常在微安范圍內(nèi).
2.在某些CMOS輸入上使用額外的上拉電阻,以允許晶振工作,而無需外部連接到控制輸入.通常選擇該值足夠低以將TTL柵極輸出上拉至高于控制輸入的閾值電壓的電壓.由于這個(gè)上拉電阻,IIL通常基于歐姆定律在毫安范圍內(nèi).NEL通常使用1.2kΩ±20％上拉電阻來確保某些控制輸入的電平.這意味著在5V±10％的電源上,IIL可以通過電阻器高達(dá)5.7mA.IIH沒有受到顯著影響,仍然依賴于IC設(shè)計(jì).
IIL is the current flow in or out of the control input (normally out of the control input) when a logic low is applied to the control input of the oscillator.
IIH is the current flow in or out of the control input (normally in to the control input) when a logic high is applied to the control input of the oscillator.
Two major factors affect the control input current flow:
1.The IC design and associated impedances.
2.Addition of any pull-up or pull-down resistors internal to our oscillator package.
NEL uses two different control input characteristics:
1.No additional resistors external to the IC are used inside the oscillator package. Thus, IIL & IIH are defined by just the IC characteristics. For CMOS inputs this is usually in the microamp range.
2.An additional pull-up resistor is used on some CMOS inputs to allow operation of the oscillator with no external connection to the control input. The value is often selected to be low enough to pull-up a TTL gate output to a voltage higher than the threshold voltage of the control input. Because of this pull-up resistor, IIL is often in the milliamp range based on ohms law. NEL typically uses a 1.2k ohm ±20% pull-up resistor to assure proper levels on some control inputs. This means on a 5V±10% power supply, the I IL could be as high as 5.7mA just through the resistor. IIH is not significantly affected and is still dependent on the IC design.
熱分析:
在HJ-100有源貼片晶振上進(jìn)行熱測(cè)量.IC尺寸為0.050’×0.050’.測(cè)量的區(qū)域是基板的頂部,封裝的底部和IC.結(jié)果如下:
環(huán)境空氣=24.2°C
封裝溫度=26.2°C
基板溫度=26.7℃
IC溫度=27.2°C
功耗=76.6mwatts
根據(jù)這些測(cè)量結(jié)果,計(jì)算出以下熱阻:
封裝至空氣i=26.11°C/瓦
IC至基板i=6.53°C/瓦
封裝至基板i=6.53°C/瓦
IC至封裝i=13.05°C/瓦
ICtoAiri=39.16°C/瓦
空氣被定義為自由不受控制的空氣.
Thermal measurements were made on an HJ-100 oscillator. IC size was 0.050" X 0.050". Areas measured were the top of the substrate, bottom of the package, and the IC. The results are as follows:
Ambient Air=24.2°C
Package Temperature=26.2°C
Substrate Temperatur=26.7°C
IC Temperature=27.2°C
Power Dissipation=76.6mwatts
Based on these measurements,the following thermal resistances were calculated:
Package to Air i=26.11°C/watt
IC to Substrate i=6.53°C/watt
Package to Substrate i=6.53°C/watt
IC to Package i=13.05°C/watt
IC to Air i=39.16°C/watt
Air is defined to be free uncontrolled air.

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此文關(guān)鍵字： NEL Oscillator 晶體振蕩器三態(tài)輸入晶振熱分析

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NEL Oscillator的熱分析與三態(tài)輸入

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