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参数资料
| 型号： | APW7077AZBI-TUL |
| 厂商： | Anpec Electronics Corporation |
| 元件分类： | DC/DC变换器 |
| 英文描述： | PWM Step-Up DC-DC Converter |
| 中文描述： | PWM升压型DC - DC转换器 |
| 文件页数： | 15/21页 |
| 文件大小： | 444K |
| 代理商： | APW7077AZBI-TUL |
Copyright
ANPEC Electronics Corp.
Rev. A.4 - S ep, 2005
APW 7077/ A
www.anpec.com.tw
15
Ex ternal Component S election
Determine the average inductor current and peak in-
ductor current:
I
L
=1.38A
I
L
=0.218A
Ipk=1.45A
Therefore, a 10 uH inductor with saturation current
larger than 1.73 A can be selected as the initial trial.
Design Example(Cont.)
External Switch Transistor
An enhancement N–channel MOSFET or a bipolar NPN
transistor can be used as the external switch transistor.
Since enhancement MOSFET is a voltage driven
device, it is a more efficient switch than a BJT
transistor. However, the MOSFET requires a higher
voltage to turn on as compared with BJT transistors.
An enhancement N–channel MOSFET can be selected
by the following guidelines:
Low ON–resistance, RDS(on).
Low gate threshold voltage, VGS(th), typically
<1.5V, it is especially important for the low V
OUT
device, like V
OUT
= 2.4V.
Rated continuous drain current, ID, should be
larger than the peak inductor current, i.e. ID > I
PK
.
Gate capacitance should be 1200 pF or less.
For bipolar NPN transistor, medium power transistor
with continuous collector current typically 1A to 5A
and VCE(sat) < 0.2 V should be employed. The driv-
ing capability is determined by the DC current gain,
HFE, of the transistor and the base resistor, Rb; and
Function Description ( Cont.)
Determine the output capacitance value for the desired
output ripple voltage:
C
OUT
=33uF
The ESR of the output capacitor is 0.05
. Therefore,
a Tantalum capacitor with value of 33 uF to 47uF and
ESR of 0.05
can be used as the output capacitor.
However, according to experimental result, 220uF
output capacitor gives better overall operational stability
and smaller ripple voltage.
Diode Selection
The output diode for a boost regulator must be cho-
sen correctly depending on the output voltage and the
output current. The diode must be rated for a reverse
voltage equal to or greater than the output voltage used.
The average current rating must be greater than the
maximum load current expected, and the peak cur-
rent rating must be greater than the peak inductor
current. During short circuit testing, or if short circuit
conditions are possible in the application, the diode
current rating must exceed the switch current limit.
The diode is the largest source of loss in DC–DC
converters. The most importance parameters which
affect their efficiency are the forward voltage drop, VF,
and the reverse recovery time, trr. The forward voltage
drop creates a loss just by having a voltage across
the device while a current flowing through it. The re-
verse recovery time generates a loss when the diode
is reverse biased, and the current appears to actually
flow backwards through the diode due to the minority
carriers being swept from the P–N junction. Using
Schottky diodes with lower forward voltage drop will
decrease power dissipation and increase efficiency.
相关PDF资料 |
PDF描述 |
|---|---|
| APW7077RBI-TR | PWM Step-Up DC-DC Converter |
| APW7077RBI-TRL | PWM Step-Up DC-DC Converter |
| APW7077RBI-TU | PWM Step-Up DC-DC Converter |
| APW7077RBI-TUL | PWM Step-Up DC-DC Converter |
| APW7077ZBI-TR | PWM Step-Up DC-DC Converter |
相关代理商/技术参数 |
参数描述 |
|---|---|
| APW7077RBI-TR | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077RBI-TRL | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077RBI-TU | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077RBI-TUL | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
| APW7077ZBI-TR | 制造商:ANPEC 制造商全称:Anpec Electronics Coropration 功能描述:PWM Step-Up DC-DC Converter |
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