參數(shù)資料
型號(hào)： NCP1205
廠商： ON SEMICONDUCTOR
英文描述： Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback
中文描述： 單端PWM控制器具有名冊(cè)操作和軟頻率折返
文件頁(yè)數(shù)： 14/20頁(yè)
文件大小： 163K
代理商： NCP1205
NCP1205
http://onsemi.com
14
As soon as the system recovers from the error, e.g. FB is
back within its regulation area, the IC operation comes back
to normal.
To avoid any system thermal runaway, another internal
8 x 128 ms delay is combined with the previous 128 ms. It
works as follows: the 128 ms delay is provided to account for
any normal transients that engender a temporary loss of
feedback (FB goes toward ground). However, when the
128 ms period is actually over (the feedback is definitively
lost) the IC stops the output driving pulses for a typical
period of 8 x 128 ms. During this mode, the rest of the
functions are still activated. For instance, in lack of pulses,
the self–supplied being no longer provided, the start–up
source turns on and off (when reaching the corresponding
UVLO
L
and UVLO
H
levels), creating an hiccup waveform
on the Vcc line. As soon as the feedback condition is
restored, the 8 x 128 ms is interrupted and, in synchronism
with the Vcc line, the IC is back to normal. The following
diagrams show how this mechanism takes place when FB is
down to zero (optocoupler opened) or up to Vcc
(optocoupler shorted). If we assume that the error is
permanently present, then a burst mode takes place with a
128/8 x 128 = 12.5% duty–cycle. The real transmitted
power is thus:
PoutBURST
1
Overvoltage Detection (OVP)
OVP detection is done differently on the DIP8 and DIP14
versions. In the DIP8, because of available pin count, the
OVP is accomplished by monitoring the Vcc voltage. On the
DIP14, the device also monitors the Vcc level but in parallel,
the triggering point has been pin–out to allow precise OVP
selection. This pin can also be used to externally latch–off
the IC.
As mentioned, Over Voltage Conditions are detected by
monitoring the Vcc level. Figure 17 describes how three
10 V zener plus one 5.0 V zener are connected in series
together with a 18 k
to ground. As soon as Vcc exceeds
40 V
typical
, a current starts to flow in the 18 k resistor.
When the voltage developed across this element exceeds
2.8 V, an error is triggered and immediately latches the IC
off. In lack of switching pulses, the Vcc capacitor is no
longer refreshed by the auxiliary supply and slowly
discharges toward ground. When the Vcc level crosses
UVLO
L
, a new startup sequence occurs. If the OVP has
gone, normal IC operation takes place. For different OVP
levels, the comparator input is accessible through pin 6 in the
DIP14 option.
Figure 17. In the DIP8 Version, the OVP Pad is not
Pinned Out and is Available with DIP14 Devices Only
–
+
+
2.8 V
Latched
OVP
5 V
10 V
18 k
10 V
10 V
6
5
4
3
2
1
7
V
CC
8
2 k
OVP
Protecting Pin 1 Against Negative Spikes
As any CMOS controller, NCP1205 is sensitive to
negative voltages that could appear on it’s pins. To avoid any
adverse latch–up of the IC, we strongly recommend
inserting a 15 k resistor in series with pin 1 and the
high–voltage rail, as shown in Figures 18 and 19. This 15 k
resistor prevents from adversely latching the controller in
case of negative spikes appearing on the bulk capacitor
during the power–off sequence. Please note that this resistor
does not dissipate any continuous power and can therefore
be of low power type. Two 8.2 k can also be wired in series
to sustain the large DC voltage present on the bulk.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
NCP1205/D 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback
NCP1205_06 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Single Ended PWM Controller Featuring QR Operation and Soft Frequency Foldback
NCP1205DR2 功能描述:IC CTRLR PWM CM OVP HV 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉(zhuǎn)換器，離線開(kāi)關(guān) 系列:- 標(biāo)準(zhǔn)包裝:1 系列:FPS™ 輸出隔離:隔離 頻率范圍:61kHz ~ 73kHz 輸入電壓:8 V ~ 26 V 輸出電壓:650V 功率（瓦特）:12W 工作溫度:-40°C ~ 115°C 封裝/外殼:8-DIP（0.300"，7.62mm） 供應(yīng)商設(shè)備封裝:8-MDIP 包裝:Digi-Reel® 其它名稱:FSL206MRBNFSDKR
NCP1205DR2G 功能描述:電流型 PWM 控制器 Single Ended Quasi Resonant PWM RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
NCP1205P 功能描述:電流型 PWM 控制器 Single Ended Quasi RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
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