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参数资料
| 型号： | MAX1904EAI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 21/33页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SPLY LN 28-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 4.2 V ~ 30 V |
| 输出数： | 4 |
| 输出电压： | 2.5 V ~ 5 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 供应商设备封装： | 28-SSOP |
| 包装： | 带卷 (TR) |
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500kHz Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
( V OUT IN ( MAX ) - V OUT )
2 × f × L × V IN ( MAX )
connected but no battery is installed. V IN(MAX) must not
exceed 30V.
Minimum Input (Battery) Voltage, V IN(MIN) .This should
be taken at full load under the lowest battery condi-
tions. If V IN(MIN) is less than 4.2V, use an external cir-
cuit to externally hold V L above the V L undervoltage
lockout threshold. If the minimum input-output differ-
ence is less than 1.5V, the filter capacitance required to
maintain good AC load regulation increases (see the
Low-Voltage Operation section).
Inductor Value
The exact inductor value isn ’ t critical and can be freely
adjusted to make trade-offs between size, cost, and
efficiency. Lower inductor values minimize size and
cost, but reduce efficiency due to higher peak-current
levels. The smallest inductor is achieved by lowering
the inductance until the circuit operates at the border
between continuous and discontinuous mode. Further
reducing the inductor value below this crossover point
results in discontinuous-conduction operation even at
full load. This helps lower output-filter capacitance
requirements, but efficiency suffers due to high I 2 R
losses. On the other hand, higher inductor values mean
greater efficiency, but resistive losses due to extra wire
LIR = ratio of AC to DC inductor current, typi-
cally 0.3; should be >0.15
The nominal peak-inductor current at full load is 1.15 ?
I OUT if the above equation is used; otherwise, the peak
current can be calculated by:
( V
I PEAK = I LOAD +
The inductor ’ s DC resistance should be low enough that
R DC ? I PEAK < 100mV, as it is a key parameter for effi-
ciency performance. If a standard off-the-shelf inductor is
not available, choose a core with an LI 2 rating greater
than L ? I PEAK 2 and wind it with the largest-diameter wire
that fits the winding area. Ferrite core material is strongly
preferred. Shielded-core geometries help keep noise,
EMI, and switching-waveform jitter low.
Current-Sense Resistor Value
The current-sense resistor value is calculated accord-
ing to the worst-case low current-limit threshold voltage
(from the Electrical Characteristics ) and the peak
inductor current:
turns will eventually exceed the benefit gained from
lower peak-current levels. Also, high inductor values
can affect load-transient response (see the V SAG equa-
R SENSE =
80mV
I PEAK
tion in the Low-Voltage Operation section). The equa-
tions that follow are for continuous-conduction
operation, since the MAX1901/MAX1902/MAX1904 are
intended mainly for high-efficiency, battery-powered
applications. Discontinuous conduction doesn ’ t affect
normal idle-mode operation.
Three key inductor parameters must be specified:
Use I PEAK from the second equation in the Inductor
Value section.
Use the calculated value of R SENSE to size the MOS-
FET switches and specify inductor saturation-current
ratings according to the worst-case high current-limit
threshold voltage:
inductance value (L), peak current (I PEAK ), and DC
resistance (R DC ). The following equation includes a
constant (LIR) which is the ratio of inductor peak-to-
peak AC current to DC load current. A higher LIR value
I PEAK ( MAX ) =
120 mV
R SENSE
V OUT ( IN ( MAX ) - V OUT )
V IN ( MAX ) × f × I OUT × LIR
allows smaller inductance, but results in higher losses
and higher ripple. A good compromise between size
and losses is found at a 30% ripple-current to load-cur-
rent ratio (LIR = 0.3), which corresponds to a peak-
inductor current 1.15 times higher than the DC load
current.
V
L =
Low-inductance resistors, such as surface-mount
metal-film, are recommended.
Input-Capacitor Value
The input filter capacitor is usually selected according
to input ripple current requirements and voltage rating,
rather than capacitor value. Ceramic capacitors or
Sanyo OS-CON capacitors are typically used to handle
the power-up surge-currents, especially when connect-
ing to robust AC adapters or low-impedance batteries.
RMS input ripple current (I RMS ) is determined by the
where:
f = switching frequency, normally 333kHz or
500kHz
I OUT = maximum DC load current
input voltage and load current, with the worst case
occurring at V IN = 2 ? V OUT :
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1904EAI-TG074 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1904ETJ | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1904ETJ+ | 功能描述:DC/DC 开关控制器 500kHz Multi-Output Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1904ETJ+T | 功能描述:DC/DC 开关控制器 500kHz Multi-Output Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1904ETJ-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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