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参数资料
| 型号： | MAX8784ETL+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/24页 |
| 文件大小： | 0K |
| 描述： | IC REG STP UP W/AMP 40-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | LCD 电视机/监控器 |
| 电源电压： | 4 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 供应商设备封装： | 40-TQFN-EP（5x5） |
| 包装： | 管件 |
Step-Up Regulator, Internal Charge Pumps, Switch
Control, and Operational Amplifier for TFT LCDs
Step-Up Regulator
D ≈ AVDD IN
The step-up regulator employs a current-mode, fixed-
frequency PWM architecture to maximize loop band-
width and to provide fast-transient response to pulsed
loads typical of TFT-LCD panel source drivers. The
integrated MOSFET and the built-in digital soft-start
function reduce the number of external components
required to control inrush currents. The output voltage
can be set from VIN to 19V with an external resistive
voltage-divider. The regulator controls the output volt-
age and output power by modulating the duty cycle (D)
of the internal power MOSFET in each switching cycle.
The duty cycle of the MOSFET is approximated by:
V ? V
V AVDD
where V AVDD is the output voltage of the step-up regulator.
CLOCK
OSCILLATOR
LOGIC
AND
DRIVER
CURRENT-LIMIT
COMPARATOR
SOFT-
START
SS
SLOPE COMP
PWM
COMPARATOR
I LIMIT
CURRENT
SENSE
LX
PGND
PWM Control Block
TO FAULT
Figure 3 is the block diagram of the step-up regulator
controller. On the rising edge of the internal oscillator
clock, the controller sets a flip-flop, turning on the
n-channel MOSFET, which applies the input voltage
across the inductor. The current through the inductor
LOGIC
1.0V
UNDERVOLTAGE
COMPARATOR
ERROR AMP
1.25V
FB
COMP
ramps up linearly. The transconductance error amplifier
compares the FB voltage with the reference voltage.
The error amplifier changes the COMP voltage by
charging or discharging the COMP capacitor. The
COMP voltage is compared with a ramp, which is the
sum of the current-sense signal and a slope compensa-
tion signal. Once the ramp signal exceeds the COMP
voltage, the controller resets the flip-flop and turns off
the MOSFET. Since the inductor current is continuous, a
transverse potential develops across the inductor that
turns on the Schottky diode (D1 in Figure 1). The voltage
across the inductor then becomes the difference
between the output voltage and the input voltage. This
discharge condition forces the current through the
inductor to ramp down, transferring the energy stored in
the magnetic field to the output capacitor and the load.
The MOSFET remains off for the rest of the clock cycle.
FREQ
Figure 3. Step-Up Regulator PWM Control Block Diagram
Soft-Start and Fault Protection
The step-up regulator achieves soft-start by linearly
ramping up its internal current limit. The soft-start termi-
nates when the output reaches regulation or the full
current limit has been reached. The current limit rises
from zero to the full current limit in approximately 3ms.
The soft-start feature effectively limits the inrush current
during startup (see the Step-Up Regulator Soft-Start
waveforms in the Typical Operating Characteristics).
The MAX8784 monitors FB for undervoltage conditions.
If the voltage is continuously below 80% of the nominal
regulation point for approximately 55ms, the MAX8784
sets the fault latch, shutting down all outputs except the
reference and the operational amplifier.
14
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相关代理商/技术参数 |
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|---|---|
| MAX8784ETL+ | 功能描述:显示驱动器和控制器 Reg, CP, Op Amp for TFT LCDs 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 |
| MAX8784ETL+T | 功能描述:显示驱动器和控制器 Reg, CP, Op Amp for TFT LCDs 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 |
| MAX8784EVKIT+ | 功能描述:显示开发工具 MAX8784 Eval Kit RoHS:否 制造商:4D Systems 产品:4Display Shields 工具用于评估:?OLED-160-G1, ?OLED-160-G2 接口类型:Serial 工作电源电压:5 V |
| MAX8785AETI+ | 功能描述:显示驱动器和控制器 Full-Bridge CCFL 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 |
| MAX8785AETI+T | 功能描述:显示驱动器和控制器 Full-Bridge CCFL 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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