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参数资料
| 型号： | SP7655EB |
| 厂商： | Exar Corporation |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7655 |
| 标准包装： | 1 |
| 系列： | * |
APPLICATIONS INFORMATION
The capacitor type suitable for the output capac-
itors can also be used for the input capacitors.
However, exercise additional caution when tanta-
lum capacitors are used. Tantalum capacitors are
known for catastrophic failure when exposed to
surge current, and input capacitors are prone to
such surge current when power supplies are con-
nected “live” to low impedance power sources.
Although tantalum capacitors have been success-
The first step of compensation design is to pick
the loop crossover frequency. High crossover
frequency is desirable for fast transient response,
but often jeopardizes the power supply stability.
Crossover frequency should be higher than the
ESR zero but less than 1/5 of the switching
frequency or 60kHz. The ESR zero is contrib-
uted by the ESR associated with the output
capacitors and can be determined by:
fully employed at the input, it is generally not
recommended.
? Z(ESR) =
1
2 C OUT R ESR
Loop Compensation Design
The open loop gain of the whole system can be
The next step is to calculate the complex conju-
gate poles contributed by the LC output filter,
divided into the gain of the error amplifier,
PWM modulator, buck converter output stage,
and feedback resistor divider. In order to cross
? P(LC) =
2
1
L C OUT
over at the desired frequency cut-off (FCO), the
gain of the error amplifier compensates for the
attenuation caused by the rest of the loop at this
frequency. The goal of loop compensation is to
manipulate loop frequency response such that
its cross-over gain at 0db, results in a slope of -
20db/dec.
When the output capacitors are of a Ceramic
Type, the SP7655 Evaluation Board requires a
Type III compensation circuit to give a phase
boost of 180 ° in order to counteract the effects of
an underdamped resonance of the output filter at
the double pole frequency.
Type III Voltage Loop
Compensation
G AMP (s) Gain Block
PWM Stage
G PWM Gain
Block
Output Stage
G OUT (s) Gain
Block
V REF
(Volts)
+
_
(SRz2Cz2+1)(SR1Cz3+1)
SR1Cz2(SRz3Cz3+1)(SRz2Cp1+1)
V IN
V RAMP_PP
(SR ESR C OUT + 1)
[S^2LC OUT +S(R ESR +R DC ) C OUT +1]
V OUT
(Volts)
Notes: R ESR = Output Capacitor Equivalent Series Resistance.
R DC = Output Inductor DC Resistance.
V RAMP_PP = SP6132 Internal RAMP Amplitude Peak to Peak Voltage.
Condition: Cz2 >> Cp1 & R1 >> Rz3
Output Load Resistance >> R ESR & R DC
Voltage Feedback
G FBK Gain Block
V FBK
(Volts)
R 2
(R 1 + R 2 )
or
V REF
V OUT
SP7655 Voltage Mode Control Loop with Loop Dynamic
Definitions:
R ESR = Output Capacitor Equivalent Series Resistance
R DC = Output Inductor DC Resistance
R RAMP_PP = SP7655 internal RAMP Amplitude Peak to Peak Voltage
Conditions:
C Z 2 >> Cp1 and R1 >> Rz3
Output Load Resistance >> R ESR and R DC
Rev E: 3/2 /07
SP7655 Wide Input Voltage Range 8A, 300kHz, Buck Regulator
? 2007 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7655ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7655ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
| SP7655ERL | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
| SP7655ER-L | 功能描述:线性稳压器 - 标准 Buck Regulator RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L |
| SP7655ERL/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
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