参数资料
| 型号： | MAX1945REUI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 15/19页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 6A 28TSSOP |
| 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： | 1.8V，2.5V，可调 |
| 输入电压： | 2.6 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 400kHz ~ 1.2MHz |
| 电流 - 输出： | 6A |
| 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： | 28-SOIC（0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 28-TSSOP 裸露焊盘 |
1MHz, 1% Accurate, 6A Internal Switch
Step-Down Regulators
Set the error-amplifier compensation zero formed by R C
and C C equal to the load-impedance pole frequency,
f PLOAD , at maximum load. Calculate C C as:
C C = (C OUT ? R OUT )/R C
500kHz Switching
The following design example is for the application cir-
cuit shown in Figures 1 and 2:
V OUT = 1.8V
I OUT(MAX) = 6A
C OUT = 180μF
R ESR = 0.04 ?
gm EA = 50μs
gmc = 18.2s
f SWITCH = 500kHz
R OUT = V OUT /I OUT(MAX) = 1.8V/6 A = 0.3 ?
fp DC = 1/(2 π ? C OUT ? (R OUT + R ESR ) = 1/(2 π ? 180 ?
10 -6 ? (0.3 + 0.04) = 2.6kHz.
fz ESR = 1/(2 π ? C OUT R ESR ) = 1/(2 π ? 180 ? 10 -6 ?
0.04) = 22.1kHz.
Pick the closed-loop unity-gain crossover frequency (f c )
at 60kHz. Determine the switching regulator DC gain:
G DC = gmc ? R OUT = 18.2 ? 0.3 = 5.46
then:
R C = (V OUT ? f C )/(gm EA ? V FB ? G DC ? fp LOAD ) =
(1.8 ? 60kHz)/(50 ? 10 -6 ? 0.8 ? 5.46 ? 2.6kHz) ≈ 190k ?
(1%), choose R C = 180k ? , 1%
C C = (C OUT ? (R OUT + R ESR ))/R C = (180uF ? (0.3 +
0.04))/180k ? ≈ 340pF, choose C C = 330pF, 10%
Table 2 shows the recommended values for R C and C C
for different output voltages.
1MHz Switching
Following procedure outlines the compensation
process of the MAX1945 for 1MHz operation with all
ceramic output capacitors (Figure 3). The basic regula-
tor loop consists of a power modulator, an output-feed-
back divider, and an error amplifier. The switching
regulator has a DC gain set by gmc ? R OUT , where
gmc is the transconductance from the output voltage of
the error amplifier to the output inductor current. The
load impedance of the switching modulator consists of
a pole-zero pair set by R OUT , the output capacitor
(C OUT ), and its ESR. The following equations define the
power train of the switching regulator:
Regulator DC Gain:
G DC = ? V OUT / ? V COMP = gmc ? R OUT
Load-Impedance Pole Frequency:
fp LOAD = 1/(2 ? π ? C OUT ? (R OUT +R ESR ))
Load-Impedance Zero Frequency:
fz ESR = 1/(2 ? π ? C OUT ? R ESR )
where, R OUT = V OUT /I OUT(MAX) , and gmc = 18.2. The
feedback divider has a gain of G FB = V FB /V OUT , where
V FB is equal to 0.8V. The transconductance error ampli-
fier has a DC gain, G EA(DC) , of 70dB. The compensa-
tion capacitor, C C , and the output resistance of the
error amplifier, R OEA (20M ? ), set the dominant pole.
C C and R C set a compensation zero. Calculate the
dominant pole frequency as:
fp EA = 1/(2 π ? C C ? R OEA )
Determine the compensation zero frequency as:
fz EA = 1/(2 π ? C C ? R C )
For best stability and response performance, set the
closed-loop unity-gain frequency much higher than the
load impedance pole frequency. In addition, set the
closed-loop unity-gain crossover frequency less than
one-fifth of the switching frequency. However, the maxi-
Table 2. Compensation Values for Output Voltages (500kHz)
VOUT (V)
R C
C C
0.8
110k ?
330pF
1.2
147k ?
330pF
1.8
180k ?
330pF
2.5
287k ?
220pF
3.3
365k ?
220pF
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1945SEUI | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1945SEUI+ | 功能描述:直流/直流开关调节器 1MHz 1% 6A Step-Down PWM RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1945SEUI+T | 功能描述:直流/直流开关调节器 1MHz 1% 6A Step-Down PWM RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1945SEUI-T | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1946ETA | 制造商:Maxim Integrated Products 功能描述:SINGLE USB SWITCH WITH AUTORESET AND FAULT BL - Rail/Tube |
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