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參數(shù)資料
| 型號(hào)： | LT1508C |
| 廠商： | Linear Technology Corporation |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Power Factor and PWM Controller(Voltage Mode) |
| 中文描述： | 功率因數(shù)和PWM控制器（電壓模式） |
| 文件頁數(shù)： | 12/16頁 |
| 文件大小： | 337K |
| 代理商： | LT1508C |
12
LT1508
The total equivalent 120Hz ripple in the output capacitor
can be calculated by:
I
HF
1.43
I
RMS
=
I
120HZ2
+
(
)
2
I
HF
= 100kHz Ripple Current.
For I
LOAD(DC)
= 0.88A, 1
120Hz
= 0.62A and the equivalent
120Hz ripple current is:
)
1.79
1.43
I
RMS
=
= 1.4A
RMS
0.62
2
+
(
2
Table 1 lists the ripple current components from lab
measurements for various output powers and line volt-
ages. The 120Hz ripple current rating at 105
°
C ambient is
1.72A for the 470
μ
F KMH 35mm
×
50mm capacitor. The
expected life of the output capacitor may be calculated
from thermal stress analysis:
(105
°
C +
T
K
) – (T
A
+
T
O
)
10
L = (L
O
)2
where
L = Expected life time
L
O
= Hours of load life at rated ripple current and rated
ambient temperature
T
K
= Capacitor internal temperature rise at rated
condition.
T
K
= (I
2
R)/(KA), where I is the rated cur-
rent, R is capacitor ESR and KA is a volume constant.
T
A
= Operating ambient temperature
T
O
= Capacitor internal temperature rise at operating
condition
APPLICATIO
S I
FOR
ATIO
U
W
U
U
Table 1. PFC Capacitor RMS Ripple Current
100W
V
INRMS
I
120HZ
I
HF
100
0.2
0.6
120
0.2
0.5
230
0.2
0.53
200W
300W
I
120HZ
0.41
0.41
0.41
I
HF
1.18
0.97
0.87
I
120HZ
0.62
0.62
0.62
I
HF
1.79
1.45
1.26
In our example, L
O
= 2000 hours assuming
T
K
= 5
°
C at
rated 1.72A.
T
O
can then be calculated from:
(
I
RMS
1.72A
T
O
=
T
K
= 5
°
C
)
2
1.4A
1.72A
= 3.3
°
C
(
)
2
Assuming the operating ambient temperature is 60
°
C, the
approximate lifetime is:
(105
°
C + 5
°
C) – (60 + 3.3
°
C)
10
L = (2000)(2)
= 50,870 Hours
For longer life a capacitor with a higher ripple current rating
or parallel capacitors should be used.
PWM Comparators
The LT1508 includes two comparators in the PWM section
which implement voltage mode PWM control. The V
C
or
control voltage pin sets duty factor. An additional current
limit comparator turns GTDR2 off in the event the I
LIM
pin
voltage exceeds 1.1V. On-chip blanking avoids reset due
to leading edge noise.
Typical Application
Figure 9 shows a 24VDC, 300W power factor corrected,
universal input supply. The 2-transistor forward converter
offers many benefits including low peak currents,
nondissipative snubber, 500VDC switches and automatic
core reset guaranteed by the LT1508’s 50% maximum
duty cycle.
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| LT1508CSW | Octal D-Type Transparent Latches With 3-State Outputs 20-SOIC 0 to 70 |
| LT1508I | Power Factor and PWM Controller(Voltage Mode) |
| LT1508IN | Power Factor and PWM Controller(Voltage Mode) |
| LT1508ISW | Power Factor and PWM Controller(Voltage Mode) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1508CN | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Power Factor and PWM Controller(Voltage Mode) |
| LT1508CSW | 功能描述:IC PWM/POWER FACTOR CNTRLR20SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - PFC（功率因數(shù)修正） 系列:- 產(chǎn)品培訓(xùn)模塊:GreenChip Synchronous Rectification Control Family of ICs 標(biāo)準(zhǔn)包裝:1 系列:- 模式:間歇導(dǎo)電（DCM） 頻率 - 開關(guān):- 電流 - 啟動(dòng):- 電源電壓:8.6 V ~ 38 V 工作溫度:-20°C ~ 150°C 安裝類型:表面貼裝 封裝/外殼:14-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:14-SO 包裝:Digi-Reel® 其它名稱:568-5348-6 |
| LT1508I | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Power Factor and PWM Controller(Voltage Mode) |
| LT1508IN | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Power Factor and PWM Controller(Voltage Mode) |
| LT1508ISW | 功能描述:IC PWM/POWER FACTOR CNTRLR20SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - PFC（功率因數(shù)修正） 系列:- 產(chǎn)品培訓(xùn)模塊:GreenChip Synchronous Rectification Control Family of ICs 標(biāo)準(zhǔn)包裝:1 系列:- 模式:間歇導(dǎo)電（DCM） 頻率 - 開關(guān):- 電流 - 啟動(dòng):- 電源電壓:8.6 V ~ 38 V 工作溫度:-20°C ~ 150°C 安裝類型:表面貼裝 封裝/外殼:14-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:14-SO 包裝:Digi-Reel® 其它名稱:568-5348-6 |
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