- 您现在的位置：买卖IC网 > PDF目录383338 > MAX1842 (Maxim Integrated Products, Inc.) 1A/2.7A, 1MHz, Step-Down Regulators with Synchronous Rectification and Internal Switches PDF资料下载
参数资料
| 型号： | MAX1842 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | 1A/2.7A, 1MHz, Step-Down Regulators with Synchronous Rectification and Internal Switches |
| 中文描述： | 1A/2.7A、1MHz、降压型稳压器，内置同步整流与开关 |
| 文件页数： | 13/16页 |
| 文件大小： | 597K |
| 代理商： | MAX1842 |
M
1A/2.7A, 1MHz, Step-Down Regulators with
Synchronous Rectification and Internal Switches
______________________________________________________________________________________
13
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 MAX1742/MAX1842
requires a minimum output ripple voltage of V
RIPPLE
≥
1% x V
OUT
.
The minimum ESR of the output capacitor should be:
Stable operation requires the correct output filter capaci-
tor. When choosing the output capacitor, ensure that:
Integrator Amplifier
An internal transconductance amplifier fine tunes the
output DC accuracy. A capacitor, C
COMP
, from COMP
to V
CC
compensates the transconductance amplifier.
For stability, choose C
COMP
= 470pF.
A large capacitor value maintains a constant average
output voltage but slows the loop response to changes
in output voltage. A small capacitor value speeds up
the loop response to changes in output voltage but
decreases stability. Choose the capacitor values that
result in optimal performance.
Soft-Start
Soft-start allows a gradual increase of the internal cur-
rent limit to reduce input surge currents at startup and
at exit from shutdown. A timing capacitor, C
SS
, placed
from SS to GND sets the rate at which the internal cur-
rent limit is changed. Upon power-up, when the device
comes out of undervoltage lockout (2.6V typ) or after
the
SHDN
pin is pulled high, a 4μA constant-current
source charges the soft-start capacitor and the voltage
on SS increases. When the voltage on SS is less than
approximately 0.7V, the current limit is set to zero. As
the voltage increases from 0.7V to approximately 1.8V,
the current limit is adjusted from 0 to the current-limit
threshold (see the
Electrical Characteristics
).The volt-
age across the soft-start capacitor changes with time
according to the equation:
The soft-start current limit varies with the voltage on the
soft-start pin, SS, according to the equation:
where I
LIMIT
is the current threshold from the
Electrical
Characteristics
.
SSI
V
V
V
I
LIMIT
SS
LIMIT
=
.
×
.
0 7
1 1
V
A
C
t
SS
SS
×
=
4
μ
C
t
V
FV
μ
s for the MAX
μ
OUT
OFF
OUT
≥
/
79
1842
C
t
V
FV
μ
s for the MAX
μ
OUT
OFF
OUT
≥
/
33
1742
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
0.7V
1.8V
I
LIMIT
t
SHDN
0
0
0
V
SS
(V)
I
LIMIT
(A)
Figure 5. Soft-Start Current Limit over Time
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1742 | Replaced by TMS320C6410 : Digital Signal Processor 40-PDIP -40 to 85 |
| MAX1742-MAX1842 | Replaced by TMS320C6410 : Digital Signal Processor 40-PDIP 0 to 0 |
| MAX1742EEE | Replaced by TMS320C6410 : |
| MAX1843 | 2.7A, 1MHz, Low-Voltage, Step-Down Regulator with Internal Synchronous Rectification in QFN Package |
| MAX1843EGI | 2.7A, 1MHz, Low-Voltage, Step-Down Regulator with Internal Synchronous Rectification in QFN Package |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1842EEE | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1842EEE+ | 功能描述:直流/直流开关调节器 1/2.7A 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 |
| MAX1842EEE+T | 功能描述:直流/直流开关调节器 1/2.7A 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 |
| MAX1842EEE-T | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1842EEE-TG074 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
发布紧急采购，3分钟左右您将得到回复。