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參數(shù)資料
| 型號(hào)： | NCP1578MNR2G |
| 廠商： | ON Semiconductor |
| 文件頁(yè)數(shù)： | 18/22頁(yè) |
| 文件大?。?/td> | 1861K |
| 描述： | IC REG DL BCK/LINEAR SYNC 20-QFN |
| 產(chǎn)品變化通告： | Product Obsolescence 19/Dec/2008 |
| 標(biāo)準(zhǔn)包裝： | 4,000 |
| 拓?fù)洌?/td> | 降壓（降壓）同步（1），線性（LDO）（1） |
| 功能： | 任何功能 |
| 輸出數(shù)： | 2 |
| 頻率 - 開(kāi)關(guān)： | 300kHz |
| 電壓/電流 - 輸出 1： | 控制器 |
| 電壓/電流 - 輸出 2： | 5V，50mA |
| 帶 LED 驅(qū)動(dòng)器： | 無(wú) |
| 帶監(jiān)控器： | 無(wú) |
| 帶序列發(fā)生器： | 是 |
| 電源電壓： | 4.5 V ~ 24 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類(lèi)型： | 表面貼裝 |
| 封裝/外殼： | 20-VFQFN 裸露焊盤(pán) |
| 供應(yīng)商設(shè)備封裝： | 20-QFN（4x4） |
| 包裝： | 帶卷 (TR) |
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NCP1578
http://onsemi.com
18
stable and high bandwidth overall loop. Worst case
component variation should be considered when selecting
the components of impedance network such that the control
loop phase margin should be greater than 45?
FREQUENCY
0dB
Modulator & Filter Gain
Open Loop Error Amp Gain
Compensation Gain
Converter Gain
Figure 36. Bode Plot of the Converter Gain
F
P1
= F
ESR
F
Z2
= F
LC
F
Z1
= 0.5 F
LC
F
ESR
F
LC
F
P2
= 0.5 F
S
Input Capacitor Selection
It is used to minimize the input voltage ripple from the
power supply source. The input capacitors should be placed
as close as possible to the drain of the high-side MOSFET
and source of the low-side MOSFET. The PCB trace style
should be in form of short and wide ones. The voltage rating
and the RMS current rating are the important parameters for
the bulk input capacitor. In typical application, the bulk
capacitor should be selected such that the voltage and
current ratings must above the maximum input voltage and
largest RMS current required by system. As a safety
guideline, the capacitor voltage rating should be at least 1.5
times greater than the maximum input voltage. And the
RMS current rating requirement is approximately half of the
DC load current. The required input capacitor RMS ripple
current rating may be estimated by the following equation:-
I
Cin(RMS)
wI
out
V
out
V
in(min)
*
V
out
V
in(min)
2
(eq. 8)
Ceramic capacitor is the good choice of the input
capacitor for notebook application due to its low ESR and
good ripple current rating and high voltage rating.
Aluminum electrolytic capacitors are also good choice.
They are relatively low cost but they should be used in
parallel connection to lower the ESR which is intrinsically
high compared with ceramic capacitors.
Output Capacitor Selection
The output capacitor's ESR will determine the output
ripple voltage and the initial voltage drop after a high
slew-rate transient. So, only specialized low-ESR
capacitors should be used for switching regulator
applications. For steady state ripple, both ESR and
capacitance of the output capacitor contribute output ripple
voltage. Normally, ESR is the dominant factor for output
ripple voltage. The output ripple voltage DV
o
can be
estimated by the following equation:
DV
o
+DI
L
ESR)
DI
L
8 C
out
F
S
(eq. 9)
and
DI
L
+
(V
in
*V
o
) V
o
L F
S
V
in
(eq. 10)
DV
o
= DI
L
X ESR if C
out
is large enough.
Where:
DI
L
= Inductor ripple current
ESR = Effective Series Resistance of the output capacitor
L = Inductance
C
out
= Output capacitance
F
S
= Switching frequency
V
in
= Input Voltage
V
o
= Regulated output voltage
From the above equations, it can be seen that the output
ripple voltage can be reduced by either using the inductor
with larger inductance or the output capacitor with smaller
ESR value. In general rule of thumb, the inductor ripple
current is typically 30% of the maximum load current and
the ripple voltage is typically 2% of the output voltage.
The output capacitor also plays an important role in
response of load step up or release transients. The voltage
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| NCP1579DR2G | 功能描述:電壓模式 PWM 控制器 BUCK CONTROLLER RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1580DR2 | 功能描述:電壓模式 PWM 控制器 Low Voltage RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1580DR2G | 功能描述:電壓模式 PWM 控制器 Low Voltage Synchronous Buck RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
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