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参数资料
| 型号： | MAX8740ETB+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 6/12页 |
| 文件大小： | 0K |
| 描述： | IC CONV DC-DC TFT-LCD 10-TDFN |
| 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： | 2.6 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 2.6 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 供应商设备封装： | 10-TDFN-EP（3x3） |
| 包装： | 带卷 (TR) |
TFT-LCD Step-Up DC-DC Converter
SHDN
SKIP
COMPARATOR
4 μ A
IN
BIAS
COMP
SKIP
SOFT-
START
SS
ERROR
FB
1.24V
AMPLIFIER
∞
ERROR
COMPARATOR
CONTROL
AND DRIVER
N
LX
LOGIC
CLOCK
GND
FREQ
OSCILLATOR
SLOPE
COMPEN-
SATION
Σ
CURRENT
SENSE
5 μ A
Figure 2. Functional Diagram
Detailed Description
The MAX8740 is a highly efficient power supply that
employs a current-mode, fixed-frequency, PWM archi-
tecture for fast transient response and low-noise opera-
tion. The device regulates the output voltage through a
combination of an error amplifier, two comparators, and
several signal generators (Figure 2). The error amplifier
compares the signal at FB to 1.24V and varies the
COMP output. The voltage at COMP determines the
current trip point each time the internal MOSFET turns
on. As the load changes, the error amplifier sources or
MAX8740
current limit depends on the duty cycle. The current
limit is determined by the following equation:
I LIM = (1.26 - 0.35 x D) x I LIM_EC
where I LIM _ EC is the current limit specified at 71% duty
cycle (see the Electrical Characteristics table) and D is
the duty cycle.
The output current capability depends on the current-
limit value and is governed by the following equation:
0 . 5 × D × V IN ? V IN
sinks current to the COMP output to command the
inductor peak current necessary to service the load. To
maintain stability at high duty cycles, a slope-compen-
sation signal is summed with the current-sense signal.
?
I OUT ( MAX ) = ? I LIM ?
? ?
?
f OSC × L ? V OUT
? × × η
At light loads, this architecture allows the MAX8740 to
“skip” cycles to prevent overcharging the output voltage.
In this region of operation, the inductor ramps up to a
peak value of approximately 150mA, discharges to the
where I LIM is the current limit calculated above, η is the
regulator efficiency (85% nominal), and D is the duty
cycle. The duty cycle when operating at the current
limit is:
output, and waits until another pulse is needed again.
Output Current Capability
The output current capability of the MAX8740 is a func-
D =
V OUT ? I LIM × R ON + V DIODE
V OUT ? V IN + V DIODE
tion of current limit, input voltage, operating frequency,
and inductor value. Because of the slope compensa-
tion used to stabilize the feedback loop, the inductor
where V DIODE is the rectifier diode forward voltage and
R ON is the on-resistance of the internal MOSFET.
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8740EUB+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX8741EAI | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8741EAI+ | 功能描述:电流和电力监控器、调节器 500kHz Multi-Out Pwr Supply Controller RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8741EAI+T | 功能描述:电流和电力监控器、调节器 500kHz Multi-Out Pwr Supply Controller RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8741EAI-T | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
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