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参数资料
| 型号： | MAX1858 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | Dual 180∑ Out-of-Phase Buck Controllers with Sequencing/Prebias Startup and POR |
| 中文描述： | 双路、180°异相、PWM降压型控制器，带有电源顺序控制及POR |
| 文件页数： | 18/22页 |
| 文件大小： | 553K |
| 代理商： | MAX1858 |
M
Dual 180° Out-of-Phase Buck Controllers with
Sequencing/Prebias Startup and POR
18
______________________________________________________________________________________
At some higher frequency, the output capacitor
’
s
impedance becomes insignificant compared to its ESR,
and the LC system becomes more like an LR system,
turning a double pole into a single pole. This zero
occurs at:
A final pole is added using C
COMP_B
to reduce the
gain and attenuate noise after crossover. This pole
(f
COMP_B
) occurs at:
Figure 10 shows a Bode plot of the poles and zeros in
their relative locations.
Near crossover, the following approximations can be
made to simplify the loop-gain equation:
R
COMP
has much higher impedance than C
COMP
.
This is true if, and only if, crossover occurs above
f
Z_COMP_A
. If this is true, C
COMP_A
can be ignored
(as a short to ground).
R
ESR
is much higher impedance than C
OUT
. This is
true if, and only if, crossover occurs well after the out-
put capacitor
’
s ESR zero. If this is true, C
OUT
becomes an insignificant part of the loop gain and can
be ignored (as a short to ground).
C
COMP_B
is much higher impedance than R
COMP
and can be ignored (as an open circuit). This is true
if, and only if, crossover occurs far below f
COMP_B
.
The following loop-gain equation can be found by using
these previous approximations with Figure 9:
Setting the loop gain to 1 and solving for the crossover
frequency yields:
To ensure stability, select R
COMP
to meet the following
criteria:
Unity-gain crossover must occur below 1/5th of the
switching frequency.
For reasonable phase margin using type 1 compen-
sation, f
CO
must be larger than 5
f
ESR
.
Choose C
COMP_A
so that f
Z_COMP_A
equals half f
LC
using the following equation:
Choose C
COMP_B
so that f
COMP_B
occurs at 3 times
f
CO
using the following equation:
C
f
R
COMP B
CO
COMP
_
=
×
×
(
)
×
1
2
3
π
C
LC
R
COMP A
OUT
COMP
_
=
×
2
f
GBW
V
V
R
V
V
R
×
g
L
CO
IN
RAMP
COMP
×
2
π
SET
OUT
ESR
M COMP
_
=
=
×
×
×
A
V
V
V
V
g
R
sL
R
L
IN
RAMP
SET
OUT
M COMP
_
COMP
ESR
×
×
×
×
f
R
COMP B
COMP COMP B
_
_
=
×
1
2
π
f
R
ESR
ESR OUT
=
×
1
2
π
COMP_
R
COMP_
C
COMP_A
C
COMP_B
g
M_COMP
P
W
M
V
C
V
SET
DH
DL
N
N
L
LX
FB
V
OUT
R
ESR
C
OUT
COMP_
R
COMP_
C
COMP_A
C
COMP_B
g
M_COMP
V
SET
L
LX
FB
R
ESR
C
OUT
GAIN = +V
IN
/V
RAMP
=
Figure 9. Fixed-Frequency Voltage-Mode Control Loop
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1858AEEG | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1858AEEG+ | 功能描述:电压模式 PWM 控制器 Dual 180 Out Buck Controllers 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 |
| MAX1858AEEG+T | 功能描述:电压模式 PWM 控制器 Dual 180 Out Buck Controllers 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 |
| MAX1858AEEG-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1858EEG | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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