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| 型号： | MAX1644EAE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/11页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 2A 16SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 76 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.1 V ~ 5.5 V |
| 输入电压： | 3 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 最高 350kHz |
| 电流 - 输出： | 2A |
| 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： | 16-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 16-SSOP |
| 产品目录页面： | 1410 (CN2011-ZH PDF) |
2A, Low-Voltage, Step-Down Regulator with
Synchronous Rectification and Internal Switches
0.01 μ F
FBSEL
SS
FB
COMP
FEEDBACK
SELECTION
MAX1644
CURRENT
IN
10 μ F
V IN
3.0V TO 5.5V
470pF
REF
G m
SENSE
SKIP
V IN
10 Ω
V CC
REF
PWM LOGIC
AND
2.2 μ F
SUMMING
COMPARATOR
DRIVERS
LX
V OUT
SHDN
C OUT
1 μ F
REF
REF
GND
TIMER
TOFF
CURRENT
SENSE
PGND
R TOFF
NOTE: HEAVY LINES DENOTE HIGH-CURRENT PATHS.
Figure 1. Functional Diagram
Synchronous Rectification
In a step-down regulator without synchronous rectifica-
tion, an external Schottky diode provides a path for cur-
rent to flow when the inductor is discharging. Replacing
the Schottky diode with a low-resistance NMOS syn-
chronous switch reduces conduction losses and
improves efficiency.
The NMOS synchronous-rectifier switch turns on follow-
ing a short delay after the PMOS power switch turns off,
thus preventing cross conduction or “shoot through.” In
constant-off-time mode, the synchronous-rectifier
switch turns off just prior to the PMOS power switch
turning on. While both switches are off, inductor current
flows through the internal body diode of the NMOS
switch. The internal body diode’s forward voltage is rel-
atively high.
Thermal Resistance
Junction-to-ambient thermal resistance, θ JA , is highly
dependent on the amount of copper area immediately
surrounding the IC leads. The MAX1644 evaluation kit
has 0.5 in. 2 of copper area and a thermal resistance of
60°C/W with no airflow. Airflow over the IC significantly
reduces the junction-to-ambient thermal resistance. For
heatsinking purposes, evenly distribute the copper area
connected at the IC among the high-current pins.
Power Dissipation
Power dissipation in the MAX1644 is dominated by
conduction losses in the two internal power switches.
Power dissipation due to supply current in the control
section and average current used to charge and dis-
charge the gate capacitance of the internal switches
are less than 30mW at 300kHz. This number is reduced
when the switching frequency decreases as the part
enters Idle Mode. Combined conduction losses in the
two power switches are approximated by:
P D = I OUT2 · R ON
The junction-to-ambient thermal resistance required to
dissipate this amount of power is calculated by:
θ JA = (T J,MAX - T A,MAX ) / P D
where: θ JA = junction-to-ambient thermal resistance
T J,MAX = maximum junction temperature
T A,MAX = maximum ambient temperature
_______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1644EAE/GH9 | 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 |
| MAX1644EAE/GH9-T | 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 |
| MAX1644EAE+ | 功能描述:直流/直流开关转换器 2A Step-Dow w/Synch Rectification 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 |
| MAX1644EAE+T | 功能描述:直流/直流开关转换器 2A Step-Dow w/Synch Rectification 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 |
| MAX1644EAE+TG116 | 制造商:Maxim Integrated Products 功能描述:2A, LOW-VOLTAGE, STEP-DOWN REGULATOR WITH SYNCHRONOUS RECTIF - Tape and Reel |
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