關(guān)于90W 電源適配器方案
誰(shuí)能幫忙提供如下規(guī)格電源的方案給我.
1.INPUT AC 100~240V 50/60Hz
2. OUTPUT 19V 4.74A 90W + PFC
3. CASE: 140L*60W*34H
謝謝! E——MAIL: xuliwu15@163.com
關(guān)于90W 電源適配器方案
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@kane
至于初級(jí)用什麼芯片,我認(rèn)為都可以,差的只是價(jià)格的問(wèn)題,但是,OUTPUT部份一定要用到同步整流,否則,效率提不上去,整個(gè)散熱將無(wú)法處理.有空請(qǐng)聯(lián)絡(luò):0755-83864136李生
你好!你有沒(méi)有19V做同步整流的經(jīng)驗(yàn)可以分享一下,我做了一款19V4.75A的適配器,用兩個(gè)雙管MBR20100并在一起用,熱的要命,MOS管沒(méi)多大溫升.我想如果是能解決同步整流技術(shù),就太美了,好象還沒(méi)見(jiàn)有過(guò).
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@再回首
你好!你有沒(méi)有19V做同步整流的經(jīng)驗(yàn)可以分享一下,我做了一款19V4.75A的適配器,用兩個(gè)雙管MBR20100并在一起用,熱的要命,MOS管沒(méi)多大溫升.我想如果是能解決同步整流技術(shù),就太美了,好象還沒(méi)見(jiàn)有過(guò).
我這里有同步整流的控制IC,型號(hào)為N3856V,專用于FLYBACK 電路.
若有技術(shù)問(wèn)題,請(qǐng)來(lái)電: 0755-83864136 OR 13760313220
1095100277.pdf
若有技術(shù)問(wèn)題,請(qǐng)來(lái)電: 0755-83864136 OR 13760313220
1095100277.pdf
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@ws0905
ML4803是PWM+PFC芯片,線路比較簡(jiǎn)單
PFC Current Sense Filtering
In DCM, the input current wave shaping technique used by the FAN4803 could cause the input current to run away. In order for this technique to be able to operate properly under DCM, the programming ramp must meet the boost inductor current down-slope at zero amps. Assuming the programming ramp is zero under light load, the OFF-time will be terminated once the inductor current reaches zero.Subsequently the PFC gate drive is initiated, eliminating the necessary dead time needed for the DCM mode. This forces the output to run away until the VCC OVP shuts down the PFC. This situation is corrected by adding an offset voltage to the current sense signal, which forces the duty cycle to zero at light loads. This offset prevents the PFC from operat-ing in the DCM and forces pulse-skipping from CCM to no-duty, avoiding DMC operation. External filtering to the cur-rent sense signal helps to smooth out the sense signal, expanding the operating range slightly into the DCM range, but this should be done carefully, as this filtering also reduces the bandwidth of the signal feeding the pulse-by-pulse current limit signal. Figure 9 displays a typical circuit for adding offset to ISENSE at light loads.
圖9見(jiàn)PDF文件,我搞不明白那個(gè)偏置電路是怎么原理!各位高手請(qǐng)幫我指點(diǎn)指點(diǎn)!1095181968.pdf
In DCM, the input current wave shaping technique used by the FAN4803 could cause the input current to run away. In order for this technique to be able to operate properly under DCM, the programming ramp must meet the boost inductor current down-slope at zero amps. Assuming the programming ramp is zero under light load, the OFF-time will be terminated once the inductor current reaches zero.Subsequently the PFC gate drive is initiated, eliminating the necessary dead time needed for the DCM mode. This forces the output to run away until the VCC OVP shuts down the PFC. This situation is corrected by adding an offset voltage to the current sense signal, which forces the duty cycle to zero at light loads. This offset prevents the PFC from operat-ing in the DCM and forces pulse-skipping from CCM to no-duty, avoiding DMC operation. External filtering to the cur-rent sense signal helps to smooth out the sense signal, expanding the operating range slightly into the DCM range, but this should be done carefully, as this filtering also reduces the bandwidth of the signal feeding the pulse-by-pulse current limit signal. Figure 9 displays a typical circuit for adding offset to ISENSE at light loads.
圖9見(jiàn)PDF文件,我搞不明白那個(gè)偏置電路是怎么原理!各位高手請(qǐng)幫我指點(diǎn)指點(diǎn)!1095181968.pdf
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