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| 型号： | MAX1974EUB+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 13/15页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 1A 10UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.75 V ~ 5.5 V |
| 输入电压： | 2.6 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 1.4MHz |
| 电流 - 输出： | 1A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 10-µMAX |
Smallest 1A, 1.4MHz Step-Down Regulators
Table 3. Recommended Inductors
MANUFACTURER
Coilcraft
Sumida
Toko
PART
LPO1704-32M
CDRD3D16-R3
A682AY-3R3M
INDUCTANCE (μH)
3.3
3.3
3.3
ESR (m ? )
160
85
134
SATURATION
CURRENT (A)
1.3
1.1
0.97
DIMENSIONS
L ? W ? H (mm)
5.5 ? 6.6 ? 1
4 ? 4 ? 1.8
4.4 ? 4.4 ? 3.1
V RIPPLE ( C ) =
I P ? P = IN OUT × OUT
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.
V RIPPLE = V RIPPLE ( C ) + V RIPPLE ( ESR )
The output voltage ripple due to the output capacitance is:
I P ? P
8 × C OUT × f SW
The output voltage ripple due to capacitor ESR is:
V RIPPLE ( ESR ) = I P ? P × ESR
I P-P is the peak-to-peak inductor current:
V ? V V
f SW × L V IN
These equations are suitable for initial capacitor selec-
tion, but final values should be set by testing a proto-
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:
× × g m ×
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
C C =
V FB
0 . 5 × I OUT ( MAX )
1 1
R CS 2 π × f C
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
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 :
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-
R C =
C OUT
C C
×
V OUT
0 . 5 × I OUT ( MAX )
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
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
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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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