参数资料
| 型号： | MAX8758ETG+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/20页 |
| 文件大小： | 0K |
| 描述： | IC REG STEP UP 24-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 1.8 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 5V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 供应商设备封装： | 24-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
Step-Up Regulator with Switch Control
and Operational Amplifier for TFT LCD
V 2 MAIN ? V IN MAIN
× V
? V IN × I INRUSH ? I MAIN × V MAIN ?
R 1 = R 2 × ? MAIN ? 1 ?
Step-Up Regulator Input Capacitor Selection
The input capacitor reduces the current peaks drawn
from the input supply and reduces noise injection into
the IC. Two 10μF ceramic capacitors are used in the
Typical Applications Circuit (Figure 1) 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, the input capacitance can be reduced below
the values used in the Typical Applications Circuit .
Step-Up Regulator Rectifier Diode
The MAX8758’s high switching frequency demands a
high-speed rectifier. Schottky diodes are recommend-
ed for most applications because of their fast recovery
time and low forward voltage. In general, a 2A Schottky
diode complements the internal MOSFET well.
Step-Up Regulator Output Voltage Selection
The output voltage of the step-up regulator can be
adjusted by connecting a resistive voltage-divider from
the output (V OUT ) to GND with the center tap connect-
ed to FB (see Figure 1). Select R2 in the 10k ? to 50k ?
range. Calculate R1 with the following equation:
? V ?
? V FB ?
where V FB , the step-up regulator’s feedback set point,
is 1.25V. Place R1 and R2 close to the IC.
Step-Up Regulator Loop Compensation
Place C COMP2 (C8 in Figure 1) from COMP to GND to
add an additional high-frequency pole. UseC COMP2
between 10pF and 47pF.
Step-Up Regulator Soft-Start Capacitor
The soft-start capacitor should be large enough that it
does not reach final value before the output has
reached regulation. Calculate the soft-start capacitor
(C SS ) value using:
C SS = 21 × 10 ? 6 × C MAIN
? ?
× ? ?
where C MAIN is the total output capacitance, V MAIN is
the maximum output voltage, and I INRUSH is the peak
inrush current allowed, I MAIN is the maximum output
current, and V IN is the minimum input voltage.
The load must wait for the soft-start cycle to finish
before drawing a significant amount of load current.
The duration after which the load can begin to draw
maximum load current is:
t MAX = 6.77 x 10 5 x C SS
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 volt-
age requirement.
The number of positive charge-pump stages is given by:
Choose R COMP (R3 in Figure 1) to set the high-frequen-
cy integrator gain for fast transient response. Choose
C COMP (C7 in Figure 1) to set the integrator zero to
n POS =
V GON ? V MAIN
V MAIN ? 2 × V D
maintain loop stability.
For low-ESR output capacitors, use the following equa-
tions to obtain stable performance and good transient
response:
where n POS is the number of positive-charge-pump
stages, V GON is the positive-charge-pump output,
V MAIN is the main step-up regulator output, and V D is
the forward voltage drop of the charge-pump diode.
n NEG =
R COMP ≈
C COMP ≈
315 × V IN × V MAIN × C MAIN
L × I MAIN ( MAX )
V MAIN × C MAIN
10 × I MAIN ( MAX ) × R COMP
The number of negative charge-pump stages is given by:
? V GOFF
V MAIN ? 2 × V D
where n NEG is the number of negative-charge-pump
stages, V GOFF is the negative charge-pump output,
To further optimize transient response, vary R COMP in
20% steps and C COMP in 50% steps while observing
transient-response waveforms.
V MAIN is the main step-up regulator output, and V D is
the forward voltage drop of the charge-pump diode.
______________________________________________________________________________________
17
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相关代理商/技术参数 |
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| MAX8758ETJ | 功能描述:LCD 驱动器 Step-Up Regulator 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 |
| MAX8758EVKIT | 功能描述:电源管理IC开发工具 MAX8758 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 |
| MAX8759AETI+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8759ETI+ | 功能描述:显示驱动器和控制器 SMBus 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 |
| MAX8759ETI+T | 功能描述:显示驱动器和控制器 SMBus 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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