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参数资料
| 型号： | MAX639ESA+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/13页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 5V/ADJ 225MA 8SOIC |
| 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： | 两者兼有 |
| 输出数： | 1 |
| 输出电压： | 5V，1.3 V ~ 11.5 V |
| 输入电压： | 4 V ~ 11.5 V |
| 电流 - 输出： | 225mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOIC |
5V/3.3V/3V/Adjustable, High-Efficiency,
Low I Q , Step-Down DC-DC Converters
______________________________________________________________Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
VOUT
LBO
LBI
GND
LX
V+
VFB
SHDN
FUNCTION
Sense Input for regulated-output operation. Internally connected to an on-chip voltage divider and to
the variable duty-cycle, on-demand oscillator. It must be connected to the external regulated output.
Low-Battery Output. An open-drain N-channel MOSFET sinks current when the voltage at LBI drops
below 1.28V.
Low-Battery Input. When the voltage at LBI drops below 1.28V, LBO sinks current.
Ground
Drain of a PMOS power switch that has its source connected to V+. LX drives the external inductor,
which provides current to the load.
Positive Supply-Voltage Input. Should not exceed 11.5V
Dual-Mode Feedback Pin. When VFB is grounded, the internal voltage divider sets the output to 5V
(MAX639), 3.3V (MAX640) or 3V (MAX653). For adjustable operation, connect VFB to an external volt-
age divider.
Shutdown Input — active low. When pulled below 0.8V, the LX power switch stays off, shutting down
the regulator. When the shutdown input is above 2V, the regulator stays on. Tie SHDN to V+ if shut-
down mode is not used.
____________________Getting Started
Designing power supplies with the MAX639/MAX640/
MAX653 is easy. The few required external components
L
I L
are readily available. The most general applications use
the following components:
(1) Capacitors: For the input and output filter capaci-
V+
V L
C OUT
V OUT
tors, try using electrolytics in the 100μF range, or
use low-ESR capacitors to minimize output ripple.
Capacitor values are not critical.
(2) Diode: Use the popular 1N5817 or equivalent
Schottky diode.
(3) Inductor: For the highest output current, choose a
100μH inductor with an incremental saturation cur-
rent rating of at least 600mA. To obtain the highest
efficiencies and smallest size, refer to the Inductor
Selection section.
_______________Detailed Description
Figure 1 shows a simplified, step-down DC-DC con-
verter. When the switch is closed, a voltage equal to
(V+ - V OUT ) is applied to the inductor. The current
Figure 1. Simplified Step-Down Converter
I L AT 200mA/div
0A
through the inductor ramps up, storing energy in the
inductor’s magnetic field. This same current also flows
into the output filter capacitor and load. When the switch
opens, the current continues to flow through the inductor
in the same direction, but must also flow through the
0V
V L AT 5V/div
diode. The inductor alone supplies current to the load
when the switch is open. This current decays to zero as
the energy stored in the inductor’s magnetic field is
SWITCH ON
SWITCH OFF
SWITCH ON
SWITCH OFF
transferred to the output filter capacitor and the load.
Figure 2. Simplified Step-Down Converter Operation
_______________________________________________________________________________________
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX639EVKIT-DIP | 制造商:Maxim Integrated Products 功能描述:5V/ADJUSTABLE, HIGH-EFFICIENCY, LOW I Q, STEP - Bulk |
| MAX639MJA | 功能描述:直流/直流开关转换器 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 |
| MAX63XXSUPEVKIT | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:Evaluation Kit for the MAX3762[MAX3762EVKIT ] |
| MAX6400BS22 | 制造商:Maxim Integrated Products 功能描述:UP SUPERVISORY CIRCUIT IN 4-BUMP 2X2 CHIP-SCA - Bulk |
| MAX6400BS22+ | 制造商:Maxim Integrated Products 功能描述:PROCESSOR SUPERVISOR 2.2V 1UA 4UCSP - Rail/Tube |
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