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參數(shù)資料
| 型號： | NCP1395A |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | High Performance Resonant Mode Controller(高性能諧振模式控制器) |
| 中文描述： | 高性能諧振模式控制器（高性能諧振模式控制器） |
| 文件頁數(shù)： | 16/27頁 |
| 文件大小： | 335K |
| 代理商： | NCP1395A |
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NCP1395A/B
http://onsemi.com
16
The designer needs to program the maximum switching
frequency and the minimum switching frequency. In LLC
configurations, for circuits working above the resonant
frequency, a high precision is required on the minimum
frequency, hence the
3% specification. This minimum
switching frequency is actually reached when no feedback
closes the loop. It can happen during the startup sequence,
a strong output transient loading or in a shortcircuit
condition. By installing a resistor from pin 1 to AGND, the
minimum frequency is set. Using the same philosophy,
wiring a resistor from pin 2 to AGND will set the maximum
frequency excursion. To improve the circuit protection
features, we have purposely created a dead zone, where the
feedback loop has no action. This is typically below 1.3 V.
Figure 34 details the arrangement where the
internal
voltage (that drives the VCO) varies between 0 and 3.6 V.
However, to create this swing, the feedback pin (to which
the optocoupler emitter connects), will need to swing
typically between 1.3 V and 6.0 V.
V
CC
FB
Rfb
+
To VCO
0 to 3.6 V
+
1.3 V
VFB = 1.36 V
Figure 34. The OPAMP arrangement limits the VCO
internal modulation signal between 0 and 5.0 V.
This technique allows us to detect a fault on the converter
in case the FB pin cannot rise above 1.3 V (to actually close
the loop) in less than a duration imposed by the
programmable timer. Please refer to the fault section for
detailed operation of this mode.
As shown in Figure 34, the
internal
dynamics of the
VCO control voltage will be constrained between 0 V and
3.6 V, whereas the feedback loop will drive pin 5 (FB)
between 1.3 V and 6.0 V. If we take the external excursion
numbers, 1.3 V = 50 kHz, 6.0 V = 1.0 MHz, then the VCO
slope will then be
1 Meg50 k
4.7
202 kHz V.
Figures 35 and 36 portray the frequency evolution
depending on the feedback pin voltage level in a different
frequency clamp combination.
VFB
F
A&B
1.3 V
6 V
Fmin
Fmax
area
No variations
No variations
50 kHz
Fsw = 950 kHz
VFB = 4.7V
0.6 V
ì
Fault
Figure 35. Maximal default excursion, Rt = 120 k
on pin 1 and Rfmax = 35 k on pin 2.
ó
ó
VFB
0.6 V
6 V
Fmin
Fmax
area
No variations
No variations
150 kHz
Fsw = 300 kHz
VFB = 4.7 V
F
A&B
1.3 V
Fault
òòòò
òòòò
Figure 36. Here a different minimum frequency
was programmed as well as a different maximum
frequency excursion.
Please note that the previous small signal VCO slope has
now been reduced to 300 k/5.0 = 62.5 kHz/V. This offers
a mean to magnify the feedback excursion on systems
where the load range does not generate a wide switching
frequency excursion. Due to this option, we will see how
it becomes possible to observe the feedback level and
implement skip cycle at light loads. It is important to note
that the frequency evolution does not have a real linear
relationship with the feedback voltage. This is due to the
deadtime presence which stays constant as the switching
period changes.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1395ADR2G | 功能描述:電壓模式 PWM 控制器 PWM CONTROLLER RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1395APG | 功能描述:電壓模式 PWM 控制器 PWM CONTROLLER RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1395B | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:High Performance Resonant Mode Controller |
| NCP1395BDR2G | 功能描述:電壓模式 PWM 控制器 PWM CONTROLLER RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1395BPG | 功能描述:電壓模式 PWM 控制器 PWM CONTROLLER RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
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