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参数资料
| 型号： | MAX1972 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | Dual, 180∑ Out-of-Phase, 1.4MHz, 750mA Step- Down Regulator with POR and RSI/PFO |
| 中文描述： | 双路、180°异相、1.4MHz、750mA、降压型调节器，带有POR和RSI/PFO |
| 文件页数： | 17/20页 |
| 文件大小： | 371K |
| 代理商： | MAX1972 |
For most designs, a reasonable inductor value (L
INIT
) is
derived from the following equation:
(
×
×
Keep the inductor current ripple percentage LIR
between 20% and 40% of the maximum load current for
best compromise of cost, size, and performance. The
maximum inductor current is:
Input Capacitor
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit
’
s switching.
The input capacitor must meet the ripple current
requirement (I
RMS
) imposed by the switching currents
defined by the following equation:
A ceramic capacitor is recommended due to its low
equivalent series resistance (ESR), equivalent series
inductance (ESL), and lower cost. Choose a capacitor
that exhibits less than a 10
°
C temperature rise at the
maximum operating RMS current for optimum long-term
reliability.
Output Capacitor
The key selection parameters for the output capacitor
are its capacitance, ESR, ESL, and the voltage rating
requirements. These affect the overall stability, output
ripple voltage, and transient response of the DC-DC
converter.
The output ripple is due to variations in the charge
stored in the output capacitor, the voltage drop due to
the capacitor
’
s ESR, and the voltage drop due to the
capacitor
’
s ESL.
The output voltage ripple due to the output capaci-
tance, ESR, and ESL is:
V
RIPPLE (ESL)
= (I
P-P
/ T
ON
)
ESL or (I
P-P
/ T
OFF
)
ESL, whichever is greater.
I
P-P
is the peak-to-peak inductor current:
These equations are suitable for initial capacitor selec-
tion, but final values should be set by testing a proto-
type or evaluation circuit. As a rule, a smaller ripple
current results in less output voltage ripple. Since the
inductor ripple current is a factor of the inductor value,
the output voltage ripple decreases with larger induc-
tance. Ceramic capacitors are recommended due to
their low ESR and ESL at the switching frequency of the
converter. For ceramic capacitors, the ripple voltage
due to ESL is negligible.
Load transient response depends on the selected out-
put capacitor. During a load transient, the output
instantly changes by ESR
I
LOAD
. Before the con-
I
V
V
×
f
L
V
V
P P
IN
OUT
SW
OUT
IN
=
×
V
I
ESR
RIPPLE(
P P
)
=
×
V
I
C
f
RIPPL( )
P P
OUT
SW
=
×
×
8
V
V
V
V
RIPPLE
RIPPL( )
RIPPLE ESR
RIPPLE ESL
=
+
+
(
)
(
)
I
V
I
V
V
(
V
I
V
V
V
RMS
IN
OUT
OUT
IN
OUT
OUT
OUT
IN
OUT
=
×
(
)
+
1
×
)
1
1
1
2
2
2
2
2
I
LIR
2
I
L MAX
(
OUT MAX
(
)
)
=
+
1
L
V
LIR
V
I
OUT MAX
(
V
V
f
INIT
OUT
IN
OUT
IN
OSC
=
)
×
)
M
Dual, 180° Out-of-Phase, 1.4MHz, 750mA Step-
Down Regulator with POR and RSI/PFO
______________________________________________________________________________________
17
Table 1. Output Voltage Settings
FBSEL1
V
CC
GND
Open
OUTPUT 1
3.3V
1.8V
Ext Divider
FBSEL2
V
CC
GND
Open
OUTPUT 2
2.5V
1.5V
Ext Divider
Table 2. Suggested Inductors
MANUFACTURER
PART
INDUCTANCE
(μH)
ESR
(m
)
SATURATION
CURRENT (A)
DIMENSIONS (mm)
Coilcraft
Sumida
Sumida
DO1606
CR43-4R7
CDRH3D16-4R7
4.7
4.7
4.7
120
108.7
80
1.2
1.15
0.9
5.3
5.3
2
4.5
4
3.5
3.8
3.8
0.8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1972EEE | 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 |
| MAX1972EEE+ | 功能描述:直流/直流开关调节器 Dual 180 Out 1.4MHz 750mA 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 |
| MAX1972EEE+T | 功能描述:直流/直流开关调节器 Dual 180 Out 1.4MHz 750mA 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 |
| MAX1972EEE-G05 | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX1972EEE-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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