参数资料
| 型号： | MAX8722CEEG+ |
| 厂商： | Maxim Integrated |
| 文件页数： | 14/21页 |
| 文件大小： | 0K |
| 描述： | IC CCFL BACKLIGHT CTRL 24-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | CCFL 控制器 |
| 频率： | 30 ~ 80 kHz |
| 电流 - 电源： | 1mA |
| 电流 - 输出： | 300mA |
| 电源电压： | 4.6 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 24-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 24-QSOP |
| 包装： | 管件 |
Low-Cost CCFL Backlight Controller
C S
1:N
L
4
AC
SOURCE
C P
CCFL
f P
3
R L INCREASING
(a)
2
C' S = S 2
C
N
L
1
f S
AC
SOURCE
C P
R L
0
0
20
40 60
FREQUENCY (kHz)
80
100
(b)
Figure 4. Equivalent Resonant Tank Circuit
The primary series capacitor is 1μF, the secondary par-
allel capacitor is 18pF, the transformer turns ratio is
1:93, 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 ):
Figure 5. Frequency Response of the Resonant Tank
the inverter behaves like a voltage source to generate
the necessary striking voltage. Theoretically, the output
voltage of the resonant converter will increase until the
lamp is ionized or until it reaches the IC’s secondary volt-
age limit, without regard to the transformer turns ratio or
the input voltage level. Once the lamp is ionized, the
equivalent load resistance decreases rapidly and the
operating point moves toward the series resonant peak.
f S =
1
2 π LC ' S
While in series resonant operation, the inverter behaves
like a current source.
Lamp-Current Regulation
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 MAX8722C uses a lamp-current control loop to
regulate the current delivered to the CCFL. The heart of
the control loop is a transconductance error amplifier.
The AC lamp current is sensed with a resistor connect-
ed in series with the low-voltage terminal of the lamp.
f P =
2 π
L
1
C ' S C P
C ' S + C P
The voltage across this resistor is fed to the IFB input
and is internally full-wave rectified. The transconduc-
tance error amplifier compares the rectified IFB voltage
with a 780mV (typ) internal threshold to generate an
error current. The error current charges and discharges
The inverter is designed to operate between these two
resonant peaks. When the lamp is off, the operating
point of the resonant tank is close to the parallel resonant
peak due to the lamp’s infinite impedance. The circuit
displays the characteristics of a parallel-loaded resonant
converter. While in parallel-loaded resonant operation,
a capacitor connected between COMP and ground to
create an error voltage (V COMP ). V COMP is then com-
pared with an internal ramp signal to set the high-side
MOSFET switch on-time (t ON ).
14
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相关代理商/技术参数 |
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| MAX8722CEEG+ | 功能描述:显示驱动器和控制器 CCFL Backlight Controller RoHS:否 制造商:Panasonic Electronic Components 工作电源电压:2.7 V to 5.5 V 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Reel |
| MAX8722CEEG+T | 功能描述:显示驱动器和控制器 CCFL Backlight Controller RoHS:否 制造商:Panasonic Electronic Components 工作电源电压:2.7 V to 5.5 V 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Reel |
| MAX8722EEG | 功能描述:显示驱动器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作电源电压:2.7 V to 5.5 V 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Reel |
| MAX8722EEG+ | 功能描述:显示驱动器和控制器 CCFL Backlight Controller RoHS:否 制造商:Panasonic Electronic Components 工作电源电压:2.7 V to 5.5 V 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Reel |
| MAX8722EEG+T | 功能描述:显示驱动器和控制器 CCFL Backlight Controller RoHS:否 制造商:Panasonic Electronic Components 工作电源电压:2.7 V to 5.5 V 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:QFN-44 封装:Reel |
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