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参数资料
| 型号： | MAX1957EUB+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 10-UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 360kHz |
| 占空比： | 96% |
| 电源电压： | 3 V ~ 5.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
Low-Cost, High-Frequency, Current-Mode PWM
Buck Controller
The MAX1953/MAX1954/MAX1957s’ response to a load
transient depends on the selected output capacitors. In
Below are equations that define the power modulator:
general, more low-ESR output capacitance results in
better transient response. After a load transient, the
output voltage instantly changes by ESR ? ? I LOAD .
G MOD = g mc ×
R LOAD × (f S × L)
R LOAD + ( f S × L )
Before the controller can respond, the output voltage
deviates further, depending on the inductor and output
capacitor values. After a short period of 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
its closed-loop bandwidth. With a higher bandwidth,
the response time is faster, preventing the output volt-
age from further deviation from its regulating value.
where R LOAD = V OUT /I OUT(MAX) , and g mc = 1/(A CS ?
R DS(ON) ), where A CS is the gain of the current-sense
amplifier and R DS(ON) is the on-resistance of the high-
side power MOSFET. A CS is 6.3 for the MAX1953 when
ILIM is connected to GND, and 3.5 for the MAX1954/
MAX1957 and for the MAX1953 when ILIM is connect-
ed to V IN or floating. The frequencies at which the pole
and zero due to the power modulator occur are deter-
mined as follows:
2 π × C OUT × ?
Compensation Design
The MAX1953/MAX1954/MAX1957 use an internal
transconductance error amplifier whose output com-
pensates the control loop. The external inductor, high-
side MOSFET, output capacitor, compensation resistor,
f pMOD =
? R
?
?
1
LOAD × ( f S × L ) + R ESR
R LOAD + ( f S × L )
?
?
?
?
and compensation capacitors determine the loop sta-
bility. The inductor and output capacitors are chosen
based on performance, size, and cost. Additionally, the
f zMOD =
1
2 π × C OUT × R ESR
compensation resistor and capacitors are selected to
optimize control-loop stability. The component values
shown in the Typical Application Circuits (Figures 1
through 4) yield stable operation over the given range
of input-to-output voltages and load currents.
The controller uses a current-mode control scheme that
regulates the output voltage by forcing the required
current through the external inductor. The MAX1953/
MAX1954/MAX1957 use the voltage across the high-
side MOSFET’s on-resistance (R DS(ON) ) to sense the
inductor current. Current-mode control eliminates the
The feedback voltage-divider used has a gain of G FB =
V FB /V OUT , where V FB is equal to 0.8V. The transcon-
ductance error amplifier has DC gain, G EA(DC) = gm ?
R O . R O is typically 10M ? . A dominant pole is set by the
compensation capacitor (C C ), the amplifier output
resistance (R O ), and the compensation resistor (R C ). A
zero is set by the compensation resistor (R C ) and the
compensation capacitor (C C ).
There is an optional pole set by C f and R C to cancel the
output capacitor ESR zero if it occurs before crossover
frequency (f C ):
double pole in the feedback loop caused by the induc-
tor and output capacitor, resulting in a smaller phase
shift and requiring less elaborate error-amplifier com-
f pdEA =
1
2 π × C C × ( R O + R C )
pensation. A simple single-series R C and C C is all that
is needed to have a stable high bandwidth loop in
applications where ceramic capacitors are used for
output filtering. For other types of capacitors, due to the
higher capacitance and ESR, the frequency of the zero
fzEA =
fpEA =
1
2 π × C C × R C
1
2 π × C f × R C
f pMOD C < S
created by the capacitance and ESR is lower than the
desired close loop crossover frequency. Another com-
pensation capacitor should be added to cancel this
ESR zero.
The basic regulator loop may be thought of as a power
modulator, output feedback divider, and an error ampli-
fier. The power modulator has DC gain set by g mc x
R LOAD , with a pole and zero pair set by R LOAD , the out-
put capacitor (C OUT ), and its equivalent series resis-
tance (R ESR ).
The crossover frequency (f C ) should be much higher
than the power modulator pole f pMOD . Also, the
crossover frequency should be less than 1/5 the
switching frequency:
f
<< f
5
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1957EUB+ | 功能描述:电流型 PWM 控制器 High-f Current-Mode PWM Buck Controller 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 |
| MAX1957EUB+T | 功能描述:电流型 PWM 控制器 High-f Current-Mode PWM Buck Controller 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 |
| MAX1957EUB-T | 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 |
| MAX19586ETN | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX19586ETN+D | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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