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参数资料
| 型号： | MAX8640YEXT25+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 5/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC 2.5V .5A SC70-6 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 2.5V |
| 输入电压： | 2.7 V ~ 5.5 V |
| 频率 - 开关： | 2MHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 6-TSSOP，SC-88，SOT-363 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | SC-70-6 |
Tiny 500mA, 4MHz/2MHz Synchronous
Step-Down DC-DC Converters
Pin Description
PIN
1
2, 5
3
4
6
NAME
LX
GND
OUT
SHDN
IN
FUNCTION
Inductor Connection to the Internal Drains of the p-channel and n-channel MOSFETs. High impedance
during shutdown.
Ground. Connect these pins together directly under the IC.
Output Sense Input. Bypass with a ceramic capacitor as close as possible to pin 3 (OUT) and pin 2 (GND).
OUT is internally connected to the internal feedback network.
Active-Low Shutdown Input. Connect to IN or logic-high for normal operation. Connect to GND or logic-low for
shutdown mode.
Supply Voltage Input. Input voltage range is 2.7V to 5.5V. Bypass with a ceramic capacitor as close as
possible to pin 6 (IN) and pin 5 (GND).
Detailed Description
The MAX8640Y/MAX8640Z step-down converters deliv-
er over 500mA to outputs from 0.8V to 2.5V. They utilize
a proprietary hysteretic PWM control scheme that
IN
switches at up to 4MHz (MAX8640Z) or 2MHz
(MAX8640Y), allowing some trade-off between efficien-
SHDN
PWM
LOGIC
LX
cy and size of external components. At loads below
100mA, the MAX8640Y/MAX8640Z automatically switch
to pulse-skipping mode to minimize the typical quies-
cent current (28μA). Output ripple remains low at all
loads, while the skip-mode switching frequency
remains ultrasonic down to 1mA (typ) loads. Figure 1 is
the simplified functional diagram.
Control Scheme
A proprietary hysteretic PWM control scheme ensures
high efficiency, fast switching, fast transient response,
low output ripple, and physically tiny external compo-
nents. This control scheme is simple: when the output
voltage is below the regulation threshold, the error
comparator begins a switching cycle by turning on the
high-side switch. This switch remains on until the mini-
mum on-time expires and the output voltage is above
the regulation threshold or the inductor current is above
the current-limit threshold. Once off, the high-side
switch remains off until the minimum off-time expires
and the output voltage falls again below the regulation
threshold. During the off period, the low-side synchro-
nous rectifier turns on and remains on until either the
high-side switch turns on again or the inductor current
approaches zero. The internal synchronous rectifier
eliminates the need for an external Schottky diode.
Voltage-Positioning Load Regulation
The MAX8640Y/MAX8640Z utilize a unique feedback
network. By taking DC feedback from the LX node, the
usual phase lag due to the output capacitor is
removed, making the loop exceedingly stable and
GND
OUT
0.6V
MAX8640Y
MAX8640Z
Figure 1. Simplified Functional Diagram
allowing the use of very small ceramic output capacitors.
This configuration yields load regulation equal to the
inductor’s series resistance multiplied by the load current.
This voltage-positioning load regulation greatly reduces
overshoot during load transients, effectively halving the
peak-to-peak output-voltage excursions compared to tra-
ditional step-down converters. See the Load-Transient
Response in the Typical Operating Characteristics.
Shutdown Mode
Connecting SHDN to GND or logic low places the
MAX8640Y/MAX8640Z in shutdown mode and reduces
supply current to 0.1μA (typ). In shutdown, the control
circuitry and internal MOSFET switches turn off and LX
becomes high impedance. Connect SHDN to IN or
logic high for normal operation.
_______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8640ZELT12+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8640ZELT12+T | 功能描述:直流/直流开关转换器 500mA 4/2MHz Synch Step-Down DC/DC Conv RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8640ZELT15+T | 制造商:Maxim Integrated Products 功能描述: |
| MAX8640ZELT18+T | 功能描述:直流/直流开关转换器 500mA 4/2MHz Synch Step-Down DC/DC Conv RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8640ZELT19+T | 功能描述:直流/直流开关转换器 500mA 4/2MHz Synch Step-Down DC/DC Conv RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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