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| 型号： | MAX17003ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 33/36页 |
| 文件大小： | 0K |
| 描述： | IC PS CTRLR FOR NOTEBOOKS 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，2 V ~ 5.5 V |
| 工作温度： | -40°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
The output capacitor and the load resistance create the
dominant pole in the system. However, the internal ampli-
5) Next, calculate the zero caused by the output
capacitor’s ESR:
fier delay, the pass transistor’s input capacitance, and the
stray capacitance at the feedback node create additional
poles in the system, and the output capacitor’s ESR gen-
erates a zero. For proper operation, use the following
f ZERO ( ESR ) =
1
2 π C OUTA R ESR
steps to ensure the linear-regulator stability:
1) First, calculate the dominant pole set by the linear
regulator’s output capacitor and the load resistor:
where R ESR is the equivalent series resistance of
C OUTA .
6) To ensure stability, choose C OUTA large enough so
f POLE ( LDO ) =
1
2 π C OUTA R LOAD
that the crossover occurs well before the poles and
zero calculated in steps 2 through 5. The poles in
steps 3 and 4 generally occur at several MHz, and
using ceramic output capacitors ensures the ESR
f POLE ( CIN ) ≈
C IN =
f POLE ( CIN ) ≈ T
f POLE ( FBA ) =
where C OUTA is the output capacitance of the aux-
iliary LDO and R LOAD is the load resistance corre-
sponding to the maximum load current. The unity-
gain crossover of the linear regulator is:
f CROSSOVER = A V(LDO) f POLE(LDO)
2) The pole caused by the internal amplifier delay is at
approximately 1MHz:
f POLE(AMP) ≈ 1MHz
3) Next, calculate the pole set by the transistor’s input
capacitance, the transistor’s input resistance, and the
base-to-emitter pullup resistor. Since the transistor’s
input resistance (h FE /g m ) is typically much greater
than the base-to-emitter pullup resistance, the pole
can be determined from the simplified equation:
1
2 π C IN R IN
g m
2 π f T
where g m is the transconductance of the pass tran-
sistor, and f T is the transition frequency. Both para-
meters can be found in the transistor’s data sheet.
Therefore, the equation can be further reduced to:
f
h FE
4) Next, calculate the pole set by the linear regulator’s
feedback resistance and the capacitance between
FBA and ground (approximately 5pF including
stray capacitance):
1
2 π C FBA ( R 5 || R 6 )
zero occurs at several MHz as well. Placing the
crossover frequency below 500kHz is typically suf-
ficient to avoid the amplifier delay pole and gener-
ally works well, unless unusual component
selection or extra capacitance moves the other
poles or zero below 1MHz.
A capacitor connected between the linear regula-
tor’s output and the feedback node can improve
the transient response and reduce the noise cou-
pled into the feedback loop.
If a low-dropout solution is required, an external p-
channel MOSFET pass transistor could be used.
However, a pMOS-based linear regulator requires
higher output capacitance to stabilize the loop. The
high gate capacitance of the p-channel MOSFET
lowers the f POLE(CIN) and can cause instability. A
large output capacitance must be used to reduce
the unity-gain bandwidth and ensure that the pole
is well above the unity-gain crossover frequency.
Applications Information
Duty-Cycle Limits
Minimum Input Voltage
The minimum input operating voltage (dropout voltage)
is restricted by the maximum duty-cycle specification
(see the Electrical Characteristics table). Keep in mind
that the transient performance gets worse as the step-
down regulators approach the dropout voltage, so bulk
output capacitance must be added (see the voltage sag
and soar equations in the Transient Response section of
the SMPS Design Procedure section). The absolute
point of dropout occurs when the inductor current ramps
down during the off-time ( Δ I DOWN ) as much as it ramps
up during the on-time ( Δ I UP ). This results in a minimum
operating voltage defined by the following equation:
______________________________________________________________________________________
33
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相关代理商/技术参数 |
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| MAX17004AETJ+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX17004ETJ+ | 功能描述:电压模式 PWM 控制器 Quad Out Main Power Supply Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17004ETJ+T | 功能描述:电压模式 PWM 控制器 Quad Out Main Power Supply Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17005AETP+ | 功能描述:电池管理 1.2MHz High-Perf Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17005AETP+T | 功能描述:电池管理 1.2MHz High-Perf Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
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