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參數(shù)資料
| 型號： | NCP1207B |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| 中文描述： | PWM電流模式控制器上運(yùn)行的免費(fèi)準(zhǔn)諧振操作 |
| 文件頁數(shù)： | 11/15頁 |
| 文件大?。?/td> | 264K |
| 代理商： | NCP1207B |
NCP1207B
http://onsemi.com
11
Latching Off the NCP1207B
In certain cases, it can be very convenient to externally
shut down permanently the NCP1207B via a dedicated
signal, e.g. coming from a temperature sensor. The reset
occurs when the user unplugs the power supply from the
mains outlet. To trigger the latchoff, a CTN (Figure 21) or
a simple NPN transistor (Figure 22) can do the work.
Figure 21. A simple CTN triggers the latchoff as
soon as the temperature exceeds a given setpoint
1
2
3
4
8
7
6
5
CTN
Aux
NCP1207B
ON/OFF
Figure 22. A simple transistor arrangement allows
to trigger the latchoff by an external signal
1
2
3
4
8
7
6
5
NCP1207B
Aux
Shutting Off the NCP1207B
Shutdown can easily be implemented through a simple
NPN bipolar transistor as depicted by Figure 23. When OFF,
Q1 is transparent to the operation. When forward biased, the
transistor pulls the FB pin to ground (V
CE(sat)
≈
200 mV) and
permanently disables the IC. A small time constant on the
transistor base will avoid false triggering (Figure 23).
Figure 23. A simple bipolar transistor totally
disables the IC
1
2
3
4
8
7
6
5
NCP1207B
10 nF
Q1
10 k
ON/OFF
1
2
3
Power Dissipation
The NCP1207B is directly supplied from the DC rail
through the internal DSS circuitry. The DSS being an
auto-adaptive circuit (e.g. the ON/OFF duty-cycle adjusts
itself depending on the current demand), the current flowing
through the DSS is therefore the direct image of the
NCP1207B current consumption. The total power
dissipation
can
be
(VHVDC
11V)
ICC2
. If we operate the device on a 250
Vac rail, the maximum rectified voltage can go up to 350
Vdc. As a result, the worse case dissipation occurs at the
maximum switching frequency and the highest line. The
dissipation is actually given by the internal consumption of
the NCP1207B when driving the selected MOSFET. The
best method to evaluate this total consumption is probably
to run the final circuit from a 50 Vdc source applied to pin 8
and measure the average current flowing into this pin.
Suppose that we find 2.0 mA, meaning that the DSS
duty-cycle
will
be
From the 350 Vdc rail, the part will dissipate:
350V
2.0mA
700mW
(however this 2.0 mA number
will drop at higher operating junction temperatures).
A DIP8 package offers a junction-to-ambient thermal
resistance R
JA
of 100
°
C/W. The maximum power
dissipation can thus be computed knowing the maximum
operating ambient temperature (e.g. 70
°
C) together with
the maximum allowable junction temperature (125
°
C):
Tjmax
TAmax
RJA
do not reach the worse consumption budget imposed by the
operating conditions. Several solutions exist to cure this
trouble:
The first one consists in adding some copper area around
the NCP1207B DIP8 footprint. By adding a min pad area
of 80 mm
2
of 35 m copper (1 oz.), R
JA
drops to about
75
°
C/W. Maximum power then grows up to 730 mW.
A resistor R
drop
needs to be inserted with pin 8 to
a) avoid
negative spikes at turn-off (see below)
b) split the power budget between this resistor and the
package. The resistor is calculated by leaving at least 50 V
on pin 8 at minimum input voltage (suppose 100 Vdc in
Vbulkmin
evaluated
using:
2.0/7.0
=
28.6%.
Pmax
550mW
. As we can see, we
our case):
Rdrop
power dissipated by the resistor is thus:
50V
7.0mA
7.1k
. The
Pdrop
VdropRMS
2
Rdrop
IDSS
Rdrop
DSSduty
cycle
2
Rdrop
7.0mA
7.1k
0.286
2
7.1k
99.5mW
Please refer to the application note AND8069 available
from www.onsemi.com/pub/ncp1200.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1207BDR2G | 功能描述:電流型 PWM 控制器 ANA QUASI RESNT SMPS RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 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 |
| NCP1207-D | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:PWM Current-Mode Controller for Free Running Quasi-Resonant Operation |
| NCP1207DR2 | 功能描述:IC CTRLR PWM CM OVP OCP HV 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉(zhuǎn)換器，離線開關(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 |
| NCP1207DR2G | 功能描述:IC CTRLR PWM CM OVP OCP HV 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - AC-DC 轉(zhuǎn)換器，離線開關(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 |
| NCP1207P | 功能描述:IC CTRLR PWM CM OVP OCP HV 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - AC-DC 轉(zhuǎn)換器，離線開關(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 |
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