參數(shù)資料
型號(hào)： MAX8729EEI
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 模擬信號(hào)調(diào)理
英文描述： Constant-Frequency, Half-Bridge CCFL Inverter Controller
中文描述： SPECIALTY ANALOG CIRCUIT, PDSO28
封裝： 0.150 INCH, 0.025 INCH PITCH, MO-137AF, QSOP-28
文件頁(yè)數(shù)： 23/26頁(yè)
文件大小： 395K
代理商： MAX8729EEI
M
Constant-Frequency, Half-Bridge CCFL
Inverter Controller
______________________________________________________________________________________
23
Figure 8 shows the frequency response of the resonant
tank’s voltage gain under different load conditions. The
primary series capacitor is 1μF, the secondary parallel
capacitor is 15pF, the transformer turns ratio is 1:78,
and the secondary leakage inductance is 260mH.
Notice that there are two peaks, f
S
and f
P
, in the fre-
quency response. The first peak, f
S
, is the series reso-
nant peak determined by the secondary leakage
inductance (L) and the series capacitor reflected to the
secondary (C’
S
):
The second peak, f
P
, is the parallel resonant peak
determined by the secondary leakage inductance (L),
the parallel capacitor (C
P
), and the series capacitor
reflected to the secondary (C’
S
):
The actual resonant frequency is between these two
resonant peaks. When the lamp is off, the operating
point of the resonant tank is close to the parallel reso-
nant peak due to the lamp’s infinite impedance. The cir-
cuit displays the characteristics of a parallel-loaded
resonant converter. While in parallel-loaded resonant
operation, the inverter behaves like a voltage source to
generate the necessary striking voltage. Theoretically,
the output voltage of the resonant converter increases
until the lamp is ionized or until it reaches the IC’s sec-
ondary voltage limit. Once the lamp is ionized, the
equivalent-load resistance decreases rapidly and the
operating point moves toward the series-resonant
peak. While in series-resonant operation, the inverter
behaves like a current source.
The leakage inductance of the CCFL transformer is an
important parameter in the resonant tank design. The
leakage inductance values can have large tolerance
and significant variations among different batches. It is
best to work directly with transformer vendors on leak-
age inductance requirements. The MAX8729 works
best when the secondary leakage inductance is
between 200mH and 350mH. The primary capacitive
dividers C1 and C2 set the minimum operating frequen-
cy, which is approximately two times the series-
resonant peak frequency. Choose:
where f
MIN
is the minimum operating frequency range.
In the circuit of Figure 1, the transformer’s turns ratio is
178 and its secondary leakage inductance is about
300mH. To set the minimum resonant frequency to
40kHz, use a capacitor of 2.2μF or less for C1 and C2.
C
C
N
2
x f
x L
MIN
1
2
8
2
2
=
≤
π
f
L
C
'
C
C
C
P
S
'
P
S
P
=
+
1
2
π
f
LC
S
S
'
=
1
2
π
C
C
P
C
P
1:N
L
R
L
AC
SOURCE
AC
SOURCE
L
(b)
(a)
C
S1
+ C
S2
C'
S
= (C
S1
+ C
S2
) / N
2
Figure 7. Simplified CCFL Inverter Circuit
FREQUENCY (kHz)
0
20
40
60
80
100
V
1
2
3
4
R
L
INCREASING
Figure 8. Frequency Response of the Resonant Tank
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX8729EEI+ 功能描述:顯示驅(qū)動(dòng)器和控制器 Const-f Half-Bridge CCFL Inverter Ctlr RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX8729EEI+T 功能描述:顯示驅(qū)動(dòng)器和控制器 Const-f Half-Bridge CCFL Inverter Ctlr RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX8729EEI-T 功能描述:顯示驅(qū)動(dòng)器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
MAX8729EVKIT 功能描述:電源管理IC開(kāi)發(fā)工具 MAX8729 Eval Kit RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
MAX872C/D 功能描述:基準(zhǔn)電壓& 基準(zhǔn)電流 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Voltage References 拓?fù)浣Y(jié)構(gòu):Shunt References 參考類型:Programmable 輸出電壓:1.24 V to 18 V 初始準(zhǔn)確度:0.25 % 平均溫度系數(shù)（典型值）:100 PPM / C 串聯(lián) VREF - 輸入電壓（最大值）: 串聯(lián) VREF - 輸入電壓（最小值）: 分流電流（最大值）:60 mA 最大工作溫度:+ 125 C 封裝 / 箱體:SOT-23-3L 封裝:Reel
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