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參數資料
| 型號： | NCP1216A |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | PWM Current-Mode Controller for High-Power Universal Off-Line Supplies |
| 中文描述： | PWM電流模式控制器的高功率通用離線用品 |
| 文件頁數： | 14/18頁 |
| 文件大小： | 182K |
| 代理商： | NCP1216A |
NCP1216, NCP1216A
http://onsemi.com
14
the MOSFET drive, establishes at 2.9 mA, we can calculate
the required capacitor using the following formula:
V·C
i
with V = 2.2 V. Then for a wanted t of 30 ms, C equals
39.5 F or a 68 F for a standard value (including
±
20%
dispersions). When an overload condition occurs, the IC
blocks its internal circuitry and its consumption drops to
350 A typical. This happens at V
CC
= 10 V and it remains
stuck until V
CC
reaches 5.6 V: we are in latchoff phase.
Again, using the selected 68 F and 350 A current
consumption, this latchoff phase lasts: 780 ms.
t
(eq. 19)
Protecting the Controller Against Negative Spikes
As with any controller built upon a CMOS technology, it
is the designer’s duty to avoid the presence of negative
spikes on sensitive pins. Negative signals have the bad habit
to forward bias the controller substrate and induce erratic
behaviors. Sometimes, the injection can be so strong that
internal parasitic SCRs are triggered, engendering
irremediable damages to the IC if a low impedance path is
offered between V
CC
and GND. If the current sense pin is
often the seat of such spurious signals, the highvoltage pin
can also be the source of problems in certain circumstances.
During the turnoff sequence, e.g. when the user unplugs the
power supply, the controller is still fed by its V
CC
capacitor
and keeps activating the MOSFET ON and OFF with a peak
current limited by R
sense
. Unfortunately, if the quality
coefficient Q of the resonating network formed by L
p
and
C
bulk
is low (e.g. the MOSFET R
dson
+ R
sense
are small),
conditions are met to make the circuit resonate and thus
negatively bias the controller. Since we are talking about ms
pulses, the amount of injected charge, (Q = I * t),
immediately latches the controller that brutally discharges
its V
CC
capacitor. If this V
CC
capacitor is of sufficient value,
its stored energy damages the controller. Figure 26 depicts
a typical negative shot occurring on the HV pin where the
brutal V
CC
discharge testifies for latchup.
Figure 26. A Negative Spike Takes Place on the Bulk Capacitor at the Switchoff Sequence
V
CC
5 V/DIV
10 ms/DIV
V
latch
1 V/DIV
0
Simple and inexpensive cures exist to prevent from
internal parasitic SCR activation. One of them consists in
inserting a resistor in series with the highvoltage pin to
keep the negative current to the lowest when the bulk
becomes negative (Figure 27). Please note that the negative
spike is clamped to (2 * V
f
) due to the diode bridge. Also,
the power dissipation of this resistor is extremely small since
it only heats up during the startup sequence.
Another option (Figure 28) consists in wiring a diode
from V
CC
to the bulk capacitor to force V
CC
to reach
VCC
ON
sooner and thus stops the switching activity before
the bulk capacitor gets deeply discharged. For security
reasons, two diodes can be connected in series.
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相關代理商/技術參數 |
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|---|---|
| NCP1216A2 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Power Factor Controllers |
| NCP1216AD100 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:PWM Current-Mode Controller for High-Power Universal Off-Line Supplies |
| NCP1216AD100R2 | 功能描述:電流型 PWM 控制器 Current Mode PWM RoHS:否 制造商:Texas Instruments 開關頻率: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 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1216AD100R2G | 功能描述:電流型 PWM 控制器 Current Mode PWM w/50% Duty Cycle Max RoHS:否 制造商:Texas Instruments 開關頻率: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 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| NCP1216AD133 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:PWM Current-Mode Controller for High-Power Universal Off-Line Supplies |
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