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参数资料
| 型号： | MAX1957EUB+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/22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
N1 operates as a duty-cycle control switch and has the
following major losses: the channel conduction loss
(P N1CC ), the voltage and current overlapping switching
loss (P N1SW ), and the drive loss (P N1DR ).
mended due to their low ESR and ESL at high frequency,
with relatively low cost. Choose a capacitor that exhibits
less than 10°C temperature rise at the maximum operat-
ing RMS current for optimum long-term reliability.
(
P N 1 CC = ? OUT ? × I 2 LOAD × R DS ( ON ) USE R DS ( ON ) AT T J ( MAX )
? V ?
? V IN ?
)
Output Capacitor
The key selection parameters for the output capacitor
are the actual capacitance value, the equivalent series
P N 2 SW = V IN × I LOAD × ? GS GD ? × f S
? Q + Q ?
? I GATE ?
where I GATE is the average DH driver output current
capability determined by:
resistance (ESR), the equivalent series inductance
(ESL), and the voltage-rating requirements. These para-
meters affect the overall stability, output voltage ripple,
and transient response. The output ripple has three
components: variations in the charge stored in the out-
put capacitor, the voltage drop across the capacitor’s
I GATE ?
1
2
×
V IN
R DH + R GATE
ESR, and the voltage drop across the ESL caused by
the current into and out of the capacitor:
P N 1 DR = Q G × V GS × f S ×
I P ? P
V RIPPLE ( ESL ) = ? IN ? ESL
I P ? P = ? IN OUT ? × ? OUT ?
where R DH is the high-side MOSFET driver’s on-resis-
tance (3 ? max) and R GATE is the internal gate resis-
tance of the MOSFET (~ 2 ? ):
R GATE
R GATE + R DH
where V GS ~ V IN . In addition to the losses above, allow
about 20% more for additional losses due to MOSFET
output capacitances and N2 body diode reverse recov-
ery charge dissipated in N1 that exists, but is not well
defined in the MOSFET data sheet. Refer to the MOS-
FET data sheet for the thermal-resistance specification
to calculate the PC board area needed to maintain the
desired maximum operating junction temperature with
the above calculated power dissipations.
The minimum load current must exceed the high-side
MOSFET’s maximum leakage current over temperature
if fault conditions are expected.
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:
V RIPPLE = V RIPPLE ( ESR ) + V RIPPLE ( C ) + V RIPPLE ( ESL )
The output voltage ripple as a consequence of the ESR,
ESL, and output capacitance is:
V RIPPLE ( ESR ) = I P ? P × ESR
V RIPPLE ( C )
8 × C OUT × f S
? V ?
? L ?
? V ? V ? ? V ?
? f S × L ? ? V IN ?
where I P-P is the peak-to-peak inductor current (see the
Determining the Inductor Value section). These equa-
tions are suitable for initial capacitor selection, but final
values should be chosen based on a prototype or eval-
uation circuit.
As a general rule, a smaller current ripple results in less
output voltage ripple. Since the inductor ripple current
is a factor of the inductor value and input voltage, the
output voltage ripple decreases with larger inductance,
and increases with higher input voltages. Ceramic
capacitors are recommended for the MAX1953 due to
its 1MHz switching frequency. For the MAX1954/
MAX1957, using polymer, tantalum, or aluminum elec-
I RMS =
I LOAD ×
V OUT × ( V IN ? V OUT )
V IN
trolytic capacitors is recommended. The aluminum
electrolytic capacitor is the least expensive; however, it
has higher ESR. To compensate for this, use a ceramic
capacitor in parallel to reduce the switching ripple and
I RMS has a maximum value when the input voltage
equals twice the output voltage (V IN = 2 x V OUT ), where
I RMS(MAX) = I LOAD /2. Ceramic capacitors are recom-
noise. For reliable and safe operation, ensure that the
capacitor’s voltage and ripple-current ratings exceed
the calculated values.
______________________________________________________________________________________
17
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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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