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| 型号： | MAX1543ETP+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/20页 |
| 文件大小： | 0K |
| 描述： | IC DC-DC CONV TFT-LCD 20-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 控制器，TFT LCD |
| 输入电压： | 2.6 V ~ 5.5 V |
| 输出数： | 2 |
| 输出电压： | 2.6 V ~ 13 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-WQFN 裸露焊盘 |
| 供应商设备封装： | 20-TQFN-EP（5x5） |
| 包装： | 管件 |
TFT LCD DC-to-DC Converter with
Operational Amplifiers
R 1 2 ? MAIN ? 1 ?
= R
operating point ( η MIN ) taken from an appropriate curve
in the Typical Operating Characteristics :
I IN(DC,MAX) = I MAIN(MAX) ? V MAIN / (V IN(MIN) ? η MIN )
Calculate the ripple current at that operating point and
the peak current required for the inductor:
I RIPPLE = V IN(MIN) ? (V MAIN -V IN(MIN) ) / (L ? f OSC ?
V MAIN )
I PEAK = I IN(DC,MAX) + (I RIPPLE ) / 2
The inductor ’ s saturation current rating and the
MAX1542/MAX1543s ’ LX current limit (I LIM ) should
exceed I PEAK and the inductor ’ s DC current rating
should exceed I IN(DC,MAX) . For reasonable efficiency,
choose an inductor with less than 0.5 ? series resis-
tance.
Considering the Typical Application Circuits , the maxi-
mum load current (I MAIN(MAX) ) is 200mA with an 8V
output and a typical input voltage of 3.3V.
Choosing an LIR of 0.6 and estimating efficiency of
85% at this operating point:
L = (3.3V) 2 ? 0.85 ? (8V - 3.3V) / ((8V) 2 ? 0.6 ? 0.2A ?
1.2MHz) = 4.7μH
Using the circuit ’ s minimum input voltage (2.7V) and
estimating efficiency of 80% at that operating point,
I IN(DC,MAX) = (0.2A ? 8V / (2.7V ? 0.8)) = 741mA
The ripple current and the peak current are:
I RIPPLE = 2.7V ? (8V - 2.7V) / (4.7μH ? 1.2MHz ? 8V)
= 317mA
I PEAK = 741mA + (317mA / 2) = 900mA
Output Capacitor Selection
The total output voltage ripple has two components: the
capacitive ripple caused by the charging and dis-
Input Capacitor Selection
The input capacitor (C IN ) reduces the current peaks
drawn from the input supply and reduces noise injec-
tion into the device. A 10μF ceramic capacitor is used
in the Typical Application Circuits (Figures 1 and 2)
because of the high source impedance seen in typical
lab setups. Actual applications usually have much
lower source impedance since the step-up regulator
often runs directly from the output of another regulated
supply. Typically, C IN can be reduced below the values
used in the Typical Application Circuits . Ensure a low-
noise supply at IN by using adequate C IN .
Output Voltage
The MAX1542/MAX1543 operate with an adjustable out-
put from V IN to 13V. Connect a resistive voltage-divider
to FB ( Typical Application Circuits ) from the output
(V MAIN ) to AGND. Select the resistor values as follows:
? V ?
? V FB ?
where V FB , the step-up converter feedback set point, is
1.24V. Since the input bias current into FB is typically
zero, R 2 can have a value up to 100k ? without sacrific-
ing accuracy, although lower values provide better
noise immunity. Connect the resistor-divider as close to
the IC as possible.
Loop Compensation
Choose R COMP to set the high-frequency integrator
gain for fast transient response. Choose C COMP to set
the integrator zero to maintain loop stability.
For low-ESR output capacitors, use the following equa-
tions to obtain stable performance and good transient
response:
charging of the output capacitance, and the ohmic rip-
ple due to the capacitor ’ s equivalent series resistance
(ESR):
V RIPPLE = V RIPPLE ( ESR ) + V RIPPLE ( C )
V RIPPLE ( ESR ) ? I PEAK x R ESR ( COUT ) , and
R COMP ?
C COMP ?
500 x V IN x V OUT x C OUT
L x I MAIN ( MAX )
V OUT x C OUT
10 x I MAIN ( MAX ) x R COMP
V RIPPLE ( C ) ? MAIN ?
I ? V MAIN ? V IN ?
?
C OUT ? V MAIN ×? OSC ?
where I PEAK is the peak inductor current (see the
Inductor Selection section). For ceramic capacitors, the
output voltage ripple is typically dominated by V RIP-
PLE(C) . The voltage rating and temperature characteris-
tics of the output capacitor must also be considered.
To further optimize transient response, vary R COMP in
20% steps and C COMP in 50% steps while observing
transient response waveforms.
Charge Pumps
Selecting the Number of Charge-Pump Stages
For highest efficiency, always choose the lowest num-
ber of charge-pump stages that meet the output
requirements. Figures 5 and 6 show the positive and
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1543ETP+ | 功能描述:LCD 驱动器 TFT LCD DC/DC Conv w/Op Amps 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 |
| MAX1543ETP+T | 功能描述:LCD 驱动器 TFT LCD DC/DC Conv w/Op Amps 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 |
| MAX1543ETP-T | 功能描述:LCD 驱动器 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 |
| MAX1543EVKIT | 功能描述:显示开发工具 MAX1542/3 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 |
| MAX1544ETL | 功能描述:电压模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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