参数资料
| 型号： | MAX8751ETJ+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 23/27页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR CCFL INV 32-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | CCFL 控制器 |
| 频率： | 30 ~ 80 kHz |
| 电流 - 电源： | 3.2mA |
| 电源电压： | 6 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
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Fixed-Frequency, Full-Bridge CCFL
Inverter Controller
C S
1:N
L
4
3
AC
SOURCE
(a)
C P
2
1
R L INCREASING
Cs' = Cs'/N 2
L
0
0
20
40
60
80
100
FREQUENCY (kHz)
AC
SOURCE
(b)
C P
R L
Figure 8. Frequency Response of the Resonant Tank
D MAX xV IN(MAX)
N1 >
B S xS xf MIN
Figure 7. Simplified CCFL Inverte r Circuit
where D MAX is the maximum duty cycle (approximately
0.4) of the high-side switch, V IN(MAX) is the maximum DC
C S ≤
N 2
4 π 2 x f 2 MIN x L
input voltage, B S is the saturation flux density of the core,
and S is the minimal cross-section area of the core.
COMP Capacitor Selection
where f MIN is the minimum operating frequency range.
In the circuit of Figure 1, the transformer’s turns ratio is
120 and its secondary leakage inductance is 200mH.
To set the minimum resonant frequency to 30kHz, use
2.2μF capacitor for C S .
The parallel capacitor CP sets the maximum operating
frequency, which is also the parallel resonant peak fre-
quency. The capacitance CP can be chosen as below:
The COMP capacitor sets the speed of the current-reg-
ulation loop that is used during startup, maintaining
lamp-current regulation, and during transients caused
by changing the input voltage. To maintain stable oper-
ation, the COMP capacitor (C COMP ) needs to be at
least 3.3nF.
As discussed in the DPWM Dimming Control section,
the COMP capacitor also limits the dynamics of the
lamp-current envelope in DPWM operation. At the end
4 π x f MAX x L x C S ? N 2
C P >
2 2
C S
of the DPWM ON cycle, the MAX8751 turns on a 100μA
internal current source to linearly discharge the COMP
capacitor. Use the following equation to set the fall time:
In the circuit of Figure 1, to set the maximum resonant
frequency to 95kHz; use 15pF for C P .
The transformer core saturation should also be consid-
C COMP =
100 μ A x t FALL
V COMP
ered when selecting the operating frequency. The pri-
mary winding should have enough turns to prevent
transformer saturation under all operating conditions.
Use the following expression to calculate the minimum
number of turns N1 of the primary winding:
where t FALL is the fall time of the lamp-current envelope
and V COMP is the dynamic COMP voltage determined
by resonant tank. At the beginning of the DPWM ON
cycle, the COMP capacitor is charged by transconduc-
tance error amplifier, so the charge current is not con-
stant. Because the average charge current is around
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23
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相关代理商/技术参数 |
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|---|---|
| MAX8751EVKIT | 功能描述:电源管理IC开发工具 MAX8751 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX8752ESA+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX8752ETA | 制造商:Maxim Integrated Products 功能描述:TFT LCD STEP-UP DC-DC CONVERTER - Rail/Tube |
| MAX8752ETA+ | 制造商:Maxim Integrated Products 功能描述:TFT LCD DC-DC CNVRTR 8TDFN EP - Rail/Tube |
| MAX8752ETA+T | 功能描述:LCD 驱动器 TFT LCD Step-Up DC/DC Converter RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
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