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参数资料
| 型号： | MAX8553EEE+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 19/24页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR BUCK PWM 16-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Quick-PWM™ |
| 应用： | 控制器，DDR，DDR2 |
| 输入电压： | 4.5 V ~ 28 V |
| 输出数： | 1 |
| 输出电压： | 可调 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-QSOP |
| 包装： | 带卷 (TR) |
4.5V to 28V Input, Synchronous PWM Buck Controllers
for DDR Termination and Point-of-Load Applications
? × I LOAD ( MAX )
I PEAK = I LOAD ( MAX ) + ?
f ESR < S
peak inductor current at the maximum-defined load
current (I LOAD(MAX) ):
? LIR ?
? 2 ?
Output-Capacitor Selection
The key selection parameters for the output capacitor
are the actual capacitance value, the ESR, the equiva-
Output-Capacitor Stability Consideration
Stability is determined by the value of the ESR zero rel-
ative to the switching frequency. To ensure stability, the
following condition must be met:
f
π
where f S is the switching frequency and:
lent series inductance (ESL), and the voltage-rating
requirements, which affect the overall stability, output
ripple voltage, and transient response.
f ESR =
1
2 π × R ESR × C OUT
The worst-case output ripple has three components:
variations in the charge stored in the output capacitor,
the voltage drop across the capacitor’s ESR, and ESL
caused by the current into and out of the capacitor.
This can be approximated by:
V RIPPLE = V RIPPLE ( ESR ) + V RIPPLE ( C ) + V RIPPLE ( ESL )
The output voltage ripple due to the ESR is:
V RIPPLE ( ESR ) = I P - P × ESR
The output voltage ripple due to the output capacitance is:
For a typical 300kHz application, the ESR zero frequen-
cy must be well below 95kHz, preferably below 50kHz.
Do not put high-value ceramic capacitors directly
across the feedback sense point without taking precau-
tions to ensure stability. Large ceramic capacitors can
have a high-ESR zero frequency and cause erratic,
unstable operation. However, it is easy to add enough
series resistance by placing the capacitors a couple of
inches downstream from the feedback sense point,
which should be as close as possible to the inductor.
The easiest method for checking stability is to apply a
very fast zero-to-max load transient and carefully
observe the output voltage-ripple envelope for over-
shoot and ringing. It can help to simultaneously monitor
the inductor current with an AC current probe. Do not
V RIPPLE ( C ) =
I P - P
8 × C OUT × f S
allow more than one cycle of ringing after the initial
step-response under- or overshoot.
The output voltage ripple due to the ESL of the output
capacitor is:
V RIPPLE (ESL) = (V IN x ESL) / (L+ESL)
I P-P is the peak-to-peak inductor current:
Input-Capacitor Selection
The input capacitor (C IN ) reduces the current peaks
drawn from the input supply and reduces noise injec-
tion. The source impedance to the input supply largely
determines the value of C IN . High source impedance
requires high input capacitance. The input capacitor
× OUT
I P - P =
V IN -V OUT
f S × L
V
V IN
must meet the ripple current requirement (I RMS )
imposed by the switching currents. The RMS input rip-
ple current is given by:
V OUT × ( V IN OUT )
After a load transient, the output voltage instantly
changes by ESR x ? I LOAD + ESL x di/dt and the con-
trollers respond within 100ns and try to regulate back to
the nominal output value.
I RMS = I LOAD ×
V IN
- V
Solid polymer or OSCON electrolytic capacitors are
recommended due to their low ESR and ESL at the
switching frequency. Higher output-current applications
require multiple output capacitors connected in parallel
to meet the output ripple-voltage requirements. Do not
exceed the capacitor’s voltage or ripple-current ratings.
I RMS has a maximum value of 1/2 I LOAD , which occurs
when V IN is twice V OUT .
For optimal circuit reliability, choose a capacitor that
has less than 10 ° C temperature rise at the peak ripple
current.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8554EEE | 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 |
| MAX8554EEE+ | 功能描述:电流型 PWM 控制器 4.5-28V Input Synch 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 |
| MAX8554EEE+T | 功能描述:电流型 PWM 控制器 4.5-28V Input Synch 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 |
| MAX8554EEE-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 |
| MAX8554EVKIT | 功能描述:电流型 PWM 控制器 Evaluation Kit for the MAX8553 MAX8554 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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