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参数资料
| 型号： | MAX1830 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | Replaced by TMS320BC52 : |
| 中文描述： | 3A、1MHz、低电压、降压型稳压器，内置同步整流与开关 |
| 文件页数： | 10/13页 |
| 文件大小： | 278K |
| 代理商： | MAX1830 |
M
3A, 1MHz, Low-Voltage, Step-Down Regulators with
Synchronous Rectification and Internal Switches
10
______________________________________________________________________________________
voltage and ground (Figure 4). Regulation is main-
tained for adjustable output voltages when V
FB
= V
REF
.
Use 30k
for R1. R2 is given by the equation:
where V
REF
is typically 1.1V.
Programming the Switching
Frequency and Off-Time
The MAX1830/MAX1831 feature a programmable PWM
mode-switching frequency, which is set by the input
and output voltage and the value of R
TOFF
, connected
from TOFF to GND. R
TOFF
sets the PMOS power switch
off-time in PWM mode. Use the following equation to
select the off-time according to your desired switching
frequency in PWM mode:
(
(
where:
t
OFF
= the programmed off-time
V
IN
= the input voltage
V
OUT
= the output voltage
V
PMOS
= the voltage drop across the internal PMOS
power switch
V
NMOS
= the voltage drop across the internal NMOS
synchronous-rectifier switch
f
PWM
= switching frequency in PWM mode
Select R
TOFF
according to the formula:
R
TOFF
= (t
OFF
- 0.07μs) (110k
/ 1.00μs)
Recommended values for R
TOFF
range from 36k
to
430k
for off-times of 0.4μs to 4μs.
Inductor Selection
The key inductor parameters must be specified: induc-
tor value (L) and peak current (I
PEAK
). The following
equation includes a constant, denoted as LIR, which is
the ratio of peak-to-peak inductor AC current (ripple
current) to maximum DC load current. A higher value of
LIR allows smaller inductance but results in higher loss-
es and ripple. A good compromise between size and
losses is found at approximately a 25% ripple-current
to load-current ratio (LIR = 0.25), which corresponds to
a peak-inductor current 1.125 times the DC load cur-
rent:
where:
I
OUT
= maximum DC load current
LIR = ratio of peak-to-peak AC inductor current to DC
load current, typically 0.25
The peak-inductor current at full load is 1.125 x I
OUT
if
the above equation is used; otherwise, the peak current
is calculated by:
Choose an inductor with a saturation current at least as
high as the peak-inductor current. The inductor you
select should exhibit low losses at your chosen operat-
ing frequency.
Capacitor Selection
The input-filter capacitor reduces peak currents and
noise at the voltage source. Use a low-ESR and low-
ESL capacitor located no further than 5mm from IN.
Select the input capacitor according to the RMS input
ripple-current requirements and voltage rating:
where I
RIPPLE
= input RMS current ripple.
The output-filter capacitor affects the output-voltage rip-
ple, output load-transient response, and feedback-loop
stability. For stable operation, the MAX1830/MAX1831
require a minimum output ripple voltage of V
RIPPLE
≥
1%
V
OUT
.
The minimum ESR of the output capacitor should be:
Stable operation requires the correct output-filter
capacitor. When choosing the output capacitor, ensure
that:
C
V
OUT
t
FV
μ
s
OUT
OFF
≥
μ
/
79
ESR
L
t
OFF
%
1
>
I
I
V
V
V
V
RIPPLE
LOAD
OUT
IN
OUT
IN
=
(
)
I
I
V
t
L
PEAK
OUT
OUT
OFF
=
+
×
×
2
L
V
t
I
LIR
OUT
OFF
OUT
×
=
×
t
V
V
V
+
f
V
V
V
OFF
IN
OUT
PMOS
PWM
IN
PMOS
NMOS
–
=
)
)
R2
R1
V
V
1
OUT
REF
=
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1830EEE | 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 |
| MAX1830EEE+ | 功能描述:直流/直流开关调节器 3A 1MHz Step-Down 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 |
| MAX1830EEE+ | 制造商:Maxim Integrated Products 功能描述:SEMICONDUCTOR ((NW)) 制造商:Maxim Integrated Products 功能描述:IC STEP-DOWN PWM DC/DC CONVERTER QSOP-16 |
| MAX1830EEE+T | 功能描述:直流/直流开关调节器 3A 1MHz Step-Down 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 |
| MAX1830EEE-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 |
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