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参数资料
| 型号： | MAX1961 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining |
| 中文描述： | 2.35V至5.5V、0.5%精度、1MHz PWM降压型控制器，带有电压裕量控制 |
| 文件页数： | 17/29页 |
| 文件大小： | 455K |
| 代理商： | MAX1961 |
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Compensation with Electrolytic Output Capacitors
The MAX1960/MAX1961/MAX1962 use a voltage-mode
control scheme that regulates the output voltage by
comparing the error-amplifier output (COMP) with a
fixed internal ramp to produce the required duty cycle.
The inductor and output capacitor create a double pole
at the resonant frequency, which has gain drop of 40dB
per decade, and phase shift of 180
°
. The error amplifier
must compensate for this gain drop and phase shift in
order to achieve a stable high-bandwidth, closed-loop
system.
The basic regulator loop consists of a power modulator,
an output feedback divider and an error amplifier. The
power modulator has DC gain set by V
IN
/V
RAMP
, with a
double pole set by the inductor and output capacitor,
and a single zero set by the output capacitor (C
O
) and
its equivalent series resistance (ESR). Below are equa-
tions that define the power modulator:
The DC gain of the power modulator is:
where V
RAMP
= 0.85
×
10
6
/ f
S
. The pole frequency due
to the inductor and output capacitor is:
The zero frequency due to the output capacitor
’
s ESR
is:
The output capacitor is usually comprised of several
same value capacitors connected in parallel. With n
capacitors in parallel, the output capacitance is:
The total ESR is:
The ESR zero (f
ZESR
) for a parallel combination of
capacitors is the same as for an individual capacitor.
The feedback divider has a gain of G
FB
= V
FB
/V
OUT
,
where V
FB
is 0.8V.
The transconductance error amplifier has DC gain
GEA(dc) of 80dB. A dominant pole is set by the com-
pensation capacitor (C
C
), the amplifier output resis-
tance (R
O
), and the compensation resistor (R
C
):
A zero is set by the compensation resistor and the
compensation capacitor:
The total closed-loop gain must equal to unity at the
crossover frequency, where the crossover frequency
should be higher than f
ZESR
, so that the -1 slope is
used to cross over at unity gain. Also, the crossover
frequency should be less than or equal to 1/5 the
switching frequency.
The loop-gain equation at the crossover frequency is:
where:
and:
The compensation resistor, R
C
, is calculated from:
where g
mEA
= 2mS.
Due to the under-damped (Q > 1) nature of the output
LC double pole, the error-amplifier compensation zero
should be approximately 0.2f
PMOD
to provide good
phase boost. C
C
is calculated from:
C
R
f
C
C
PMOD
=
×
×
5
2
π
R
V
g
V
G
C
OUT
FB
mEA
MOD f
=
×
×
( )
G
G
f
f
f
MOD f
MOD DC
PMOD
ESR
C
( )
(
)
(
×
)
×
=
2
G
g
R
EA f
mEA
C
( )
×
=
V
V
G
G
FB
OUT
EA f
MOD f
×
×
( )
( )
=
1
f
f
f
ZESR
C
S
5
<
≤
f
C
R
ZEA
C
C
=
×
×
1
2
π
f
C
R
R
PEA
C
C
=
×
+
1
2
0
π
(
)
R
R
n
ESR
ESR EACH
(
=
)
C
n
C
O
EACH
=
×
f
R
C
ZESR
ESR
O
=
×
×
1
2
π
f
L C
PMOD
O
=
1
2
π
G
V
V
MOD DC
IN
RAMP
(
)
=
M
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM
Step-Down Controllers with Voltage Margining
______________________________________________________________________________________
17
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1962 | 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining |
| MAX1962EEP | 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining |
| MAX19700 | 10-Bit, 45Msps, Ultra-Low-Power Analog Front-End |
| MAX19705 | 10-Bit, 45Msps, Ultra-Low-Power Analog Front-End |
| MAX19706 | 10-Bit, 45Msps, Ultra-Low-Power Analog Front-End |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1961EEP | 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 |
| MAX1961EEP+ | 功能描述:DC/DC 开关控制器 1MHz PWM Step-Down 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 |
| MAX1961EEP+T | 功能描述:DC/DC 开关控制器 1MHz PWM Step-Down 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 |
| MAX1961EEP-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 |
| MAX1962EEP | 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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