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参数资料
| 型号： | MAX1974EUB |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | Smallest 1A, 1.4MHz Step-Down Regulators |
| 中文描述： | 2.4 A SWITCHING REGULATOR, 1600 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封装： | MICRO, SOP-10 |
| 文件页数： | 13/15页 |
| 文件大小： | 331K |
| 代理商： | MAX1974EUB |
response of the DC-DC converter. With ceramic capaci-
tors, the voltage ripple from ESL is negligible.
Output ripple is generated by variations in the charge
stored in the output capacitance, and the voltage drop
across the capacitor ESR.
The output voltage ripple due to the output capacitance is:
V
RIPPLE( )
8
The output voltage ripple due to capacitor ESR is:
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. Because
the inductor ripple current is inversely proportional to
inductor value, output voltage ripple decreases with
larger inductance.
Load transient response depends on the selected output
capacitor. During a load transient, the output voltage
instantly changes by ESR
I
LOAD
. Before the controller
can respond, the output deviates further, depending on
the inductor and output capacitor values. After a short
time (see the
Typical Operating Characteristics
), the
controller responds by regulating the output voltage
back to its nominal state. The controller response time
depends on the closed-loop bandwidth. With a higher
bandwidth the response time is faster. However, to main-
tain stable operation, the bandwidth should not be set
above f
SW
/10.
Compensation Components
An internal transconductance error amplifier compen-
sates the control loop. Connect a series resistor and
capacitor between COMP and GND to form a pole-zero
pair. The external inductor, output capacitor, compen-
sation resistor, and compensation capacitor determine
the loop bandwidth and stability. The inductor and out-
put capacitor are chosen based on performance, size,
and cost. Additionally, the compensation resistor and
capacitor are selected to optimize the control loop.
Table 4 and Table 5 list typical component values. The
rest of this section is a more detailed discussion on cal-
culating compensation components.
The controller uses a current-mode control scheme that
regulates the output voltage by forcing the required
current through the external inductor. The voltage
across the internal high-side MOSFET
’
s on-resistance
is used to sense inductor current. Current-mode control
eliminates the double pole caused by the inductor and
output capacitor found in other control schemes.
Simple Type 1 compensation with a single resistor (R
C
)
and capacitor (C
C
) is all that is needed to provide a
stable and high-bandwidth loop.
Use the formula below to calculate the value of C
C
,
then use the nearest standard value:
where V
FB
is 1.25V for the MAX1973 and 0.75V for the
MAX1974, the current-sense transresistance (R
CS
) is
0.26
(typ), and the transconductance from FB to
COMP (g
m
) is 50μS (typ). For best stability and
response performance, the closed-loop unity-gain fre-
quency (f
C
) should be approximately 140kHz (one-
tenth the switching frequency).
Use the following equation to calculate R
C
:
Below is a numerical example of calculating compen-
sation values for a circuit using the MAX1973 with 2.5V
output and maximum output current of 1A:
MAX1973
R
C
C
V
I
OUT MAX
(
C
OUT
C
OUT
=
×
×
0 5
)
C
V
I
R
g
f
C
FB
OUT MAX
(
CS
m
C
=
×
×
×
×
×
0 5
.
1
1
2
)
π
I
V
V
f
L
V
V
P P
IN
OUT
×
SW
OUT
IN
=
×
V
I
ESR
RIPPLE ESR
P P
(
)
=
×
I
C
f
P P
OUT
SW
=
×
×
V
V
V
RIPPLE
RIPPL( )
RIPPLE ESR
=
+
(
)
M
Smallest 1A, 1.4MHz Step-Down Regulators
______________________________________________________________________________________
13
MANUFACTURER
PART
INDUCTANCE (μH)
ESR (m
)
SATURATION
CURRENT (A)
DIMENSIONS
L
W
H (mm)
Coilcraft
Sumida
Toko
LPO1704-32M
CDRD3D16-R3
A682AY-3R3M
3.3
3.3
3.3
160
85
134
1.3
1.1
0.97
5.5
6.6
1
4
4
1.8
4.4
4.4
3.1
Table 3. Recommended Inductors
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1974EUB+ | 功能描述:直流/直流开关调节器 1A 1.4MHz Step-Down Regulator 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 |
| MAX1974EUB+T | 功能描述:直流/直流开关调节器 1A 1.4MHz Step-Down Regulator 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 |
| MAX1974EUB-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 |
| MAX1974EUB-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 |
| MAX1974EUB-TG05 | 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 |
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