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| 型号： | IR3637ASTRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 9/19页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 660kHz |
| 占空比： | 76% |
| 电源电压： | 4.5 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： | 0°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 其它名称： | IR3637ASTRPBFDKR |
IR3637ASPbF
F ESR = ---(8)
Note that this method requires that the output capacitor
should have enough ESR to satisfy stability requirements.
In general the output capacitor’s ESR generates a zero
typically at 5KHz to 50KHz which is essential for an
acceptable phase margin.
The ESR zero of the output capacitor expressed as fol-
lows:
1
2 π × ESR × Co
V OUT
Where:
V IN = Maximum Input Voltage
V OSC = Oscillator Ramp Voltage
Fo = Crossover Frequency
F ESR = Zero Frequency of the Output Capacitor
F LC = Resonant Frequency of the Output Filter
R 5 and R 6 = Resistor Dividers for Output Voltage
Programming
g m = Error Amplifier Transconductance
For:
V IN = 5.5V
V OSC = 1.25V
R 6 Fb
R 5
V REF
E/A
Comp
C 9
R 4
Ve
C POLE
Fo = 60KHz
F ESR = 26.5KHz
F LC = 9.20KHz
R 5 = 1K
R 6 = 1.25K
g m = 600 μ mho
Gain(dB)
H(s) dB
This results to R 4 =16.06K ? . Choose R 4 =16K ?
To cancel one of the LC filter poles, place the zero be-
fore the LC filter resonant frequency pole:
F Z
Frequency
Figure 9 - Compensation network without local
feedback and its asymptotic gain plot.
F Z ? 75%F LC
F Z ? 0.75 ×
For:
2 π
1
L O × C O
---(13)
The transfer function (Ve / V OUT ) is given by:
Lo = 1.0 μ H
Co = 300 μ F
(
) × 1 + sC sR C
H(s) = g m ×
R 5
R 6 + R 5
4 9
9
---(9)
F Z = 6.9KHz
R 4 = 16K ?
Using equations (11) and (13) to calculate C 9 , we get:
|H(s)| = g m ×
× R 4
---(10)
F Z =
---(11)
C 9 × C POLE
2 π × R 4 ×
The (s) indicates that the transfer function varies as a
function of frequency. This configuration introduces a gain
and zero, expressed by:
R 5
R 6 × R 5
1
2 π× R 4 × C 9
The gain is determined by the voltage divider and E/A's
transconductance gain.
First select the desired zero-crossover frequency (Fo):
Fo > F ESR and F O ≤ (1/5 ~ 1/10) × f S
C 9 = 1.44nF
Choose C 9 = 1.5nF
One more capacitor is sometimes added in parallel with
C 9 and R 4 . This introduces one more pole which is mainly
used to supress the switching noise. The additional pole
is given by:
1
F P =
C 9 + C POLE
The pole sets to one half of switching frequency which
results in the capacitor C POLE:
× × g m
V IN
F LC2
R 5
π× R 4 × f S - 1
for F P <<
Use the following equation to calculate R 4 :
V OSC Fo × F ESR R 5 + R 6 1
R 4 = ×
---(12)
C POLE =
f S
2
1
C 9
?
1
π× R 4 × f S
www.irf.com
9
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相关代理商/技术参数 |
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|---|---|
| IR3637SPBF | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| IR3637STRPBF | 功能描述:开关变换器、稳压器与控制器 2 CH OR 2 PHASE SYNC PWM CNTRLR 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 |
| IR3638 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:High Frequency Synchronous |
| IR3638DR2G | 制造商:ON Semiconductor 功能描述: |
| IR3638SPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER FOR TRACKING APPLIACTIONS |
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