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参数资料
| 型号： | SP7651EB |
| 厂商： | Exar Corporation |
| 文件页数： | 9/15页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7651 |
| 标准包装： | 1 |
| 系列： | * |
APPLICATIONS INFORMATION
when tantalum 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 connected “live”
to low impedance power sources.
Loop Compensation Design
The open loop gain of the whole system
can be divided into the gain of the error
amplifier, PWM modulator, buck converter
output stage, and feedback resistor divider.
In order to cross over at the selected fre-
quency 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 gain
crosses over 0db at a slope of -20db/dec.
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 higher than the ESR zero but less than
/5 of the switching frequency. The ESR
zero is contributed by the ESR associated
with the output capacitors and can be de-
termined by:
system stability. Crossover frequency should
be higher than the ESR zero but less than
/5 of the switching frequency. The ESR
zero is contributed by the ESR associated
with the output capacitors and can be de-
termined by:
? Z(ESR) = .
2π C OUT R ESR
The next step is to calculate the complex
conjugate poles contributed by the LC
output filter,
? P(LC) = .
2π √ L C OUT
When the output capacitors are Ceramic
type, the SP765 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 V oltage 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
[S^2LC
(SR
OUT
ESR C OUT + 1)
+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 RA MP Amplitude Peak to Peak V oltage.
Output Load Resistance >> R
Condition: Cz2 >> Cp1 & R1 >> Rz3
ESR
&R
DC
Voltage Feedback
G FBK Gain Block
V FBK
R 2
(R 1 + R 2 )
or
V REF
V OUT
(Volts)
SP765 Voltage Mode Control Loop with Loop Dynamic
Definitions:
R ESR = Output Capacitor Equivalent Series Resistance
R DC = Output Inductor DC Resistance
R RAMP_PP = SP765 internal RAMP Amplitude Peak-to-Peak Voltage
Rev J: 3/ 4/07
SP765 Wide Input Voltage Range 3A, 900kHz, Buck Regulator
9
? Copyright 2007 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7651ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7651ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 3A, 900kHz, Buck Regulator |
| SP7651ER-L | 功能描述:DC/DC 开关控制器 Buck Regulator RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| SP7651ER-L/TR | 功能描述:开关变换器、稳压器与控制器 WIDE INPUT VOLTAGE RANGE, 3A 900k RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| SP7652 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 6A, 600kHz, Buck Regulator |
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