参数资料
| 型号： | MAX8751ETJ+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 17/27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
the end of the DPWM on-cycle, the dimming control
logic turns on a 100μA internal current source, thus dis-
charging the COMP capacitor linearly, gradually
decreasing t ON and bringing lamp current to zero, thus
providing soft-start. The dimming control for the CCFL
is provided by changing the duty ratio of the low-fre-
quency DPWM signal.
Using the Internal Oscillator
When the MAX8751 is not using an external synchro-
nization signal, the DPWM signal is generated using an
internal oscillator. The frequency of the internal DPWM
oscillator is adjustable through a resistor connected
between LF and GND. The DPWM frequency is given
by the following equation:
Using the External DPWM Signal
To use the external DPWM signal to control the bright-
ness, connect SEL to V CC and connect LSYNC to the
external signal source. The frequency range of the exter-
nal signal is within ±40% of the internal oscillator fre-
quency set by R LF . In this mode, the brightness control
input CNTL is disabled, and the brightness is proportion-
al to the duty cycle of the external signal. When the duty
cycle of the external signal is 100%, the CCFL reaches
full brightness. If the duty cycle of the external signal is
less than 10%, the CCFL brightness stays at 10%.
Lamp-Out Protection
For safety, the IFB pin on MAX8751 monitors the lamp
current to detect faulty or open CCFL lamps. As
described in the Lamp-Current Regulation section, the
f DPWM =
208Hz x 150k ?
R LF
voltage on IFB is internally full-wave rectified. If the rec-
tified IFB voltage is below 790mV, the MAX8751
charges the TFLT capacitor with a 1μA current source.
The adjustable range of the DPWM frequency is between
80Hz and 300Hz (R LF is between 390k ? and 104k ? ).
The CCFL brightness is proportional to the DPWM duty
cycle, which can be adjusted from 10% to 100%
through the CNTL pin. CNTL is an analog input with a
usable input voltage range between 0 and 2000mV,
which is digitized to select one of 128 brightness levels.
As shown in Figure 5, the MAX8751 ignores the first 13
steps, and the first 13 steps (V CNTL between 0 and
203mV) all represent 10% brightness. When V CNTL is
above 203mV, a 15.625mV change on CNTL results in
a 0.78% change in the DPWM duty cycle. When V CNTL
is equal to or above 2000mV, the DPWM duty cycle is
always 100%.
100
90
80
70
60
50
40
30
20
10
0
The fault latch is set if the voltage on TFLT exceeds 4V.
Unlike normal shutdown mode, the linear regulator out
(V CC ) remains at 5.35V. Toggling SHDN or cycling the
input power reactivates the device.
During the fault delay period, the current-control loop
tries to maintain the lamp-current regulation by increas-
ing the on-time of high-side MOSFETs. Because the
lamp impedance is very high when it is open, the trans-
former secondary rises as a result of the high-Q factor
of the resonant tank. Once the secondary voltage
exceeds the overvoltage threshold, the MAX8751 turns
on a 1200μA internal current source that discharges the
COMP capacitor. The on-time of the high-side
MOSFETs is reduced, lowering the secondary voltage,
as the COMP voltage decreases. Therefore, the peak
voltage of the transformer secondary winding never
exceeds the limit during the lamp-out delay period.
Primary Overcurrent Protection
The MAX8751 provides cycle-by-cycle primary over-
current protection. A current-sense amplifier monitors
the drain-to-source voltages of both the high-side and
low-side switches when the switches are conducting. If
the voltage exceeds the internal current-limit threshold
(400mV typ), the regulator turns off the high-side switch
at the opposite side of the primary to prevent the trans-
former primary current from increasing further.
0
400
800
1200
1600
2000
CNTL VOLTAGE (mV)
Figure 5. Brightness vs. CNTL Voltage
______________________________________________________________________________________
17
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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 |
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| 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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