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參數(shù)資料
| 型號(hào)： | NCP1216P65 |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | PWM Current-Mode Controller for High-Power Universal Off-Line Supplies |
| 中文描述： | 0.5 A SWITCHING CONTROLLER, 71.5 kHz SWITCHING FREQ-MAX, PDIP7 |
| 封裝： | PLASTIC, DIP-8/7 |
| 文件頁(yè)數(shù)： | 10/18頁(yè) |
| 文件大?。?/td> | 182K |
| 代理商： | NCP1216P65 |
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NCP1216, NCP1216A
http://onsemi.com
10
Dynamic SelfSupply
The DSS principle is based on the charge/discharge of the
V
CC
bulk capacitor from a low level up to a higher level. We
can easily describe the current source operation with a bunch
of simple logical equations:
POWERON: If V
CC
< VCC
OFF
then the Current Source
is ON, no output pulses
If V
CC
decreasing > VCC
ON
then the Current Source is
OFF, output is pulsing
If V
CC
increasing < VCC
OFF
then the Current Source is
ON, output is pulsing
Typical values are: VCC
OFF
= 12.2 V, VCC
ON
= 10 V
To better understand the operational principle, Figure 18
offers the necessary light:
10
30
50
70
90
Figure 18. The Charge/Discharge Cycle Over a
10 F V
CC
Capacitor
VCC
OFF
= 12.2 V
VCC
ON
= 10 V
V
ripple
= 2.2 V
ON, I = 8 mA
OFF, I = 0 mA
Output Pulse
The DSS behavior actually depends on the internal IC
consumption and the MOSFET’s gate charge Q
g
. If we
select a 600 V 10 A MOSFET featuring a 30 nC Q
g
, then we
can compute the resulting average consumption supported
by the DSS which is:
Itotal
Fsw
Qg
ICC1.
(eq. 1)
The total IC heat dissipation incurred by the DSS only is
given by:
Itotal
Vpin8.
(eq. 2)
Suppose that we select the NCP1216P065 with the above
MOSFET, the total current is
(30 n
65 k)
900
2.9 mA.
(eq. 3)
Supplied from a 350 VDC rail (250 VAC), the heat
dissipated by the circuit would then be:
350 V
2.9 mA
1 W
(eq. 4)
As you can see, it exists a tradeoff where the dissipation
capability of the NCP1216 fixes the maximum Q
g
that the
circuit can drive, keeping its dissipation below a given
target. Please see the “Power Dissipation” section for a
complete design example and discover how a resistor can
help to heal the NCP1216 heat equation.
Application note AND8069/D details tricks to widen the
NCP1216 driving implementation, in particular for large Q
g
MOSFETs. This document can be downloaded at
www.onsemi.com/pub/Collateral/AND8069D.PDF
Ramp Compensation
Ramp compensation is a known mean to cure
subharmonic oscillations. These oscillations take place at
half the switching frequency and occur only during
Continuous Conduction Mode (CCM) with a dutycycle
greater than 50%. To lower the current loop gain, one usually
injects between 50% and 100% of the inductor downslope.
Figure 19 depicts how internally the ramp is generated:
CS
L.E.B
19 k
2.9V
0V
Figure 19. Inserting a Resistor in Series with the
Current Sense Information brings Ramp
Compensation
+
From Setpoint
R
sense
R
comp
DC
max
= 75
°
C
In the NCP1216, the ramp features a swing of 2.9 V with
a Duty cycle max at 75%. Over a 65 kHz frequency, it
corresponds to a
2.9
0.75
In our FLYBACK design, let’s suppose that our primary
inductance L
p
is 350 H, delivering 12 V with a Np : Ns
ratio of 1:0.1. The OFF time primary current slope is thus
given by:
Np
Ns
65 kHz
251 mV
s ramp.
(eq. 5)
Vout
Vf
Lp
371 mA
s or37 mV
s
(eq. 6)
when projected over an R
sense
of 0.1 , for instance. If we
select 75% of the downslope as the required amount of
ramp compensation, then we shall inject 27 mV/ s. Our
internal compensation being of 251 mV/ s, the divider ratio
(divratio) between R
comp
and the 19 k is 0.107. A few lines
of algebra to determine R
comp
:
19 k
divratio
1
divratio
2.37 k
(eq. 7)
Frequency Jittering
Frequency jittering is a method used to soften the EMI
signature by spreading the energy in the vicinity of the main
switching component. NCP1216 offers a
4% deviation of
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| NCP1216P65G | 功能描述:電流型 PWM 控制器 Current Mode 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 |
| NCP1217 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Enhanced PWM Current-Mode Controller for High-Power Universal Off-Line Supplies |
| NCP1217/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Enhanced PWM Current-Mode Controller for High-Power Universal Off-line supplies |
| NCP1217_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Enhanced PWM Current−Mode Controller for High−Power Universal Off−Line Supplies |
| NCP1217_10 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Enhanced PWM Current--Mode Controller for High--Power Universal Off--Line Supplies |
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