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参数资料
| 型号： | SP7663EB |
| 厂商： | Exar Corporation |
| 文件页数： | 13/18页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP7663 |
| 标准包装： | 1 |
| 系列： | * |
S P 7 6 6 3
P o w e r b l o x T M
6 A 6 0 0 K H z S y n c h r o n o u s S t e p D o w n R e g u l a t o r
I PK-PK = peak-to-peak inductor ripple current
The total output ripple is a combination of the
ESR and the output capacitance value and can
be calculated as follows:
? V IN ?
I OUT ( MAX ) ? R ESR ( CIN ) ?
I OUT ( MAX ) ? V OUT ? ? V IN ? V OUT ?
V IN 2 ? fs ? C IN
? I PP ? ? 1 ? D ? ?
? ? ? I PP ? R ESR ?
? ?
? V OUT
2
? fs ? C OUT ?
2
The capacitor type suitable for the output
capacitors can also be used for the input
capacitors. However, exercise extra caution
fs = Switching Frequency
D = Duty Cycle
C OUT = output capacitance value
I NPUT C APACITOR S ELECTION
The input capacitor should be selected for
ripple current rating, capacitance and voltage
rating. The input capacitor must meet the
ripple current requirement imposed by the
switching current. In continuous conduction
mode, the source current of the high-side
MOSFET is approximately a square wave of
duty cycle V OUT /V IN . More accurately, the
current wave form is trapezoidal, given a finite
turn-on and turn-off, switch transition slope.
Most of this current is supplied by the input
bypass capacitors. The RMS current handling
capability of the input capacitors is determined
at maximum output current and under the
assumption that the peak-to-peak inductor
ripple current is low, it is given by:
I CIN ( RMS ) ? I OUT ( MAX ) ? D ? 1 ? D ?
The worst case occurs when the duty cycle D
is 50% and gives an RMS current value equal
to Iout/2. Select input capacitors with
adequate ripple current rating to ensure
reliable operation.
The power dissipated in the input capacitor is:
P CIN = I 2CIN(RMS) ? R ESR(CIN)
This can become a significant part of power
losses in a converter and hurt the overall
energy transfer efficiency. The input voltage
ripple primarily depends on the input capacitor
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. Although
tantalum capacitors have been successfully
employed at the input, it is generally not
recommended.
L OOP C OMPENSATION D ESIGN
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 desired frequency cut-off (fco), the
gain of the error amplifier must compensate
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
crossover gain at 0db, results in a slope of
-20db/decade.
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 contributed by the ESR
associated with the output capacitors and can
be determined by:
ESR and capacitance. Ignoring the inductor
ripple current, the input voltage ripple can be
determined by:
? 2012 Exar Corporation
13/18
f Z ? ESR ? ?
1
2 ? ? C OUT R ESR
Rev. 2.2.0
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PDF描述 |
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| SP7662EB | EVAL BOARD FOR SP7662 |
| SP7655EB | EVAL BOARD FOR SP7655 |
| SP7653EB | EVAL BOARD FOR SP7653 |
| A9CAA-0804F | FLEX CABLE - AFG08A/AF08/AFG08T |
| LM2735YSDEVAL | BOARD EVAL LM2735 520KHZ 6LLP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SP7663ER | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7663ER/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 6A, 600kHz, Buck Regulator |
| SP7663ER-L | 功能描述:开关变换器、稳压器与控制器 Buck Regulator 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 |
| SP7663ERL/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Wide Input Voltage Range 6A, 600kHz, Buck Regulator |
| SP7663ER-L/TR | 功能描述:开关变换器、稳压器与控制器 WIDE INPUT VOLTAGE Range6A600KHz 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 |
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