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参数资料
| 型号： | MAX8744AETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 29/36页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP QUAD 32TQFN |
| 标准包装： | 2,500 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 6 V ~ 26 V |
| 输出数： | 4 |
| 输出电压： | 3.3V，5V，1 V ~ 26 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
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High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
Do not put high-value ceramic capacitors directly
across the feedback sense point without taking precau-
tions to ensure stability. Large ceramic capacitors can
have a high ESR zero frequency and cause erratic,
unstable operation. However, it is easy to add enough
series resistance by placing the capacitors a couple of
inches downstream from the feedback sense point,
which should be as close as possible to the inductor.
Unstable operation manifests itself in two related, but
distinctly different ways: short/long pulses and cycle
skipping, which results in lower frequency operation.
Instability occurs due to noise on the output or because
the ESR is so low that there is not enough voltage ramp
in the output voltage signal. This “fools” the error com-
parator into triggering too early or into skipping a cycle.
Cycle skipping is more annoying than harmful, resulting
in nothing worse than increased output ripple.
However, it can indicate the possible presence of loop
instability due to insufficient ESR. Loop instability can
result in oscillations at the output after line or load
steps. Such perturbations are usually damped, but can
cause the output voltage to rise above or fall below the
tolerance limits.
The easiest method for checking stability is to apply a
very fast zero-to-max load transient and carefully
observe the output-voltage-ripple envelope for over-
shoot and ringing. It may help to simultaneously moni-
tor the inductor current with an AC current probe. Do
not allow more than three cycles of ringing after the ini-
tial step-response under/overshoot.
Input Capacitor Selection
The input capacitor must meet the ripple current
requirement (I RMS ) imposed by the switching currents.
For an out-of-phase regulator, the total RMS current in
the input capacitor is a function of the load currents,
the input currents, the duty cycles, and the amount of
overlap as defined in Figure 8.
INPUT CAPACITOR RMS CURRENT
vs. INPUT VOLTAGE
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
IN PHASE
50/50 INTERLEAVING
40/60 OPTIMAL
INTERLEAVING
6
8
10
12
14
16
18
20
V IN (V)
INPUT RMS CURRENT FOR INTERLEAVED OPERATION:
? I IN ) ( D LX 5 ? D OL ) + ( I OUT 3 ? I IN ) ( D LX 3 ? D OL ) + ( I OUT 5 + I OUT 3 ? I IN
I RMS =
( OUT 5
2 2
)
2
D OL + I IN 2 ( 1 ? D LX 5 ? D LX 3 + D OL
)
D LX 5 = OUT 5
D LX 3 = OUT 3
V
V IN
V
V IN
D OL = DUTY ? CYCLE OVERLAP FRACTION
I IN =
V OUT5 I OUT5 + V OUT3 I OUT3
V IN
INPUT RMS CURRENT FOR SINGLE-PHASE OPERATION:
= I
?
?
?
?
I RMS LOAD ?
?
V OUT ( V IN ? V OUT
V IN
) ? ?
?
?
Figure 8. Input RMS Current
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8744AEVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX8744A EVAL KIT - Rail/Tube |
| MAX8744ETJ+ | 功能描述:电流型 PWM 控制器 Quad-Out Main Power Supply Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8744ETJ+T | 功能描述:电流和电力监控器、调节器 Quad-Out Main Power 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 |
| MAX8744EVKIT | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY QUAD OUTPUT MAIN - Rail/Tube |
| MAX8744EVKIT+ | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY QUAD OUTPUT MAIN - Rail/Tube |
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