- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄362330 > AN-35 LinkSwitch Design Guide PDF資料下載
參數(shù)資料
| 型號(hào)： | AN-35 |
| 英文描述： | LinkSwitch Design Guide |
| 中文描述： | 使用LinkSwitch設(shè)計(jì)指南 |
| 文件頁(yè)數(shù)： | 8/16頁(yè) |
| 文件大?。?/td> | 504K |
| 代理商： | AN-35 |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)當(dāng)前第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)第16頁(yè)
AN-35
8
B
4/03
Figure 7. Example of Battery Model Load (Values for a Typical
3 W, 5.5 V Battery Charger).
with stable dielectrics (NPO or COG, for example) are higher
cost. The value of low cost ceramic capacitors varies significantly
with voltage and temperature (Z5U dielectric, for example) and
should not be used since they may cause output oscillation.
CONTROL Pin Capacitor (C
CP
)
C
sets the auto-restart period and also the time the output has
to reach regulation before entering auto-restart at power supply
start-up. If the load is a battery, then a value of 0.22
μ
F is
typical. However, if the supply is required to start into a
resistive load or constant current load (such as a bench electronic
load) at the peak output power point, then this should be
increased to 1
μ
F. This ensures enough time during start-up to
bring the output into regulation. The type of capacitor is not
critical. Either a small ceramic or electrolytic may be used with
a voltage rating of 10 V or more.
Output Rectifier and Filter (D
OUT
, C
OUT
)
The output diode should be selected with an adequate peak
inverse voltage (PIV) rating. Either PN or Schottky diodes can
be used. Schottky diodes offer higher efficiency at higher cost
but provide the most linear CC output characteristic. Both fast
or ultra fast PN diodes may be used, but ultra fast (t
~50 ns)
are preferred giving CC linearity close to the performance of a
Schottky.
The output diode voltage rating should be calculated from
Equation 26. V
is the maximum primary DC rail voltage
(375 V for universal or 230 VAC and 187 V for 115 VAC only
designs). The output voltage V
is multiplied by 1.5 to allow for
increased output voltage at no-load. An output diode current
rating of 2
x
I
O
is a good initial estimate.
The output diode may be placed in either the upper or lower leg
of the secondary winding. However, placement in the lower leg
may provide lower conducted EMI with a suitably constructed
transformer.
For battery charger applications, the size and cost of the output
capacitor C
can be significantly reduced. High ripple current
flows through C
for only the short time a fully depleted
battery charges. The designer should take into account that
C
ripple current rating can be exceeded for short periods of
time without reducing lifetime significantly. When the battery
is close to fully charged, the
LinkSwitch
circuit transitions to
CV mode, where capacitor ripple current is much smaller.
PI-2975-072402
(26)
At no-load, increasing R
slightly increases the no-load voltage
since the primary leakage inductance is filtered more effectively,
but the same peak charging due to secondary leakage inductance
occurs. Although the no-load voltage is slightly higher, there is
only a minor effect on no-load consumption.
In a design that has high leakage, the value of R
can be
increased to raise the overall output voltage (Figure 6). However,
this will also increase no-load voltage and therefore no-load
input power consumption.
To iterate R
LF
:
Start with typical value of 100
and a transformer with
nominal inductance.
Verify CC portion of the curve and increase or decrease
R
until CC curve is approximately vertical (current at
start of CC and end are approximately the same)
Verify CV portion of the curve.
- For minor adjustment, change value of R
FB
.
Clamp Capacitor (C
CLAMP
)
With small values of clamp capacitor C
, the output voltage
tends to be slightly higher. With larger values for C
, output
voltage will be slightly lower. Further increases in C
CLAMP
will
not change the output voltage.
C
is therefore chosen empirically as the smallest value that
does not significantly change the output voltage when compared
to the next larger value. For most designs, 100 nF is typical and
standard device tolerances will have a negligible effect on the
output voltage. This capacitor should be rated above the V
OR
,
typically 100 V.
C
must have a stable value over temperature and also over
the operating voltage range. Metalized plastic film capacitors
are the best choice, since the higher voltage ceramic capacitors
PIV D
V
N
N
V
OUT
DC MAX
(
S
P
O
≥
×
+
×
(
)
)
.5
2 x 1N4001
R
CABLE
R
LOAD
R
INT_RES
10,000
μ
F
R
CABLE
= 0.23
R
INT_RES
= 0.5
R
LOAD
= 11
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AN002M4-78 | SP4T RF Absorptive Switch |
| AN002R2-29 | SPDT RF Reflective Switch |
| AN002R2-53 | SPDT RF Reflective Switch |
| AN1081 | Voltage-Feedback Operational Amplifier |
| AN1081S | Voltage-Feedback Operational Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AN3500-521P | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:AN0625-521P |
| AN3501FBP | 制造商:Panasonic Industrial Company 功能描述:IC |
| AN3501NFBP | 制造商:PANASONIC 制造商全稱:Panasonic Semiconductor 功能描述:Luminance, chroma and linear audio signal processing IC for VCR |
| AN350-4 | 制造商:AN# - MILITARY 功能描述: |
| AN3-52A | 制造商:AN# - MILITARY 功能描述: |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。