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參數(shù)資料
| 型號： | VB408B |
| 廠商： | 意法半導體 |
| 英文描述： | HIGH VOLTAGE LINEAR REGULATOR POWER I.C. |
| 中文描述： | 高電壓線性穩(wěn)壓電源集成電路 |
| 文件頁數(shù)： | 3/8頁 |
| 文件大?。?/td> | 57K |
| 代理商： | VB408B |
VB408 / VB408B / VB408FI
3/8
1
Figure 1:
Typical application diagram
OPERATION DESCRIPTION
The VB408, VB408B, VB408FI are positive voltage
regulators continuously adjustable from 1.25V to the input
voltage minus a dropout of 30V through an external
divider. In order to set the proper internal reference
voltage, a typical 70
μ
A current has to be drawn from the
ADJ pin. Considering that, it results:
V
OUT =
V
REF
(1+R
2
/R
1
) + I
ADJ
R
2
To simplify this formula, neglecting I
ADJ
with respect to
the term
V
REF
/R
1
R
1
must be chosen so to obtain aminimum 1.2mA current
flowing through the divider. In such a way the V
OUT
value
will be affected by an error <5%. The current set resistor
R
1
should be tied directly to the output terminal of the
regulator rather than near the load. This eliminates line
drops from appearing in series with the reference and
degrading regulation. The output voltage can also be set
by a zener diode put between the adjustment pin and
ground (Figure 2). The biasing current of the zener is
properly chosen by R
1
resistor. The zener diode improves
the ripple rejection and reduces the value of the worst
case output voltage error. In this case the output voltage
is given by:
V
OUT
= V
REF
+V
Z
In order to reduce excessive output ringing, a minimum
output capacitor C
2
of 0.1
μ
F is suggested. This capacitor
will improve loop stability and output impedance. The
VB408/VB408B/VB408FI can be connected both to a DC
source or to a 285V r.m.s. line by a rectifier diode that
prevents a negative voltage to be applied to the device. In
the first case the input capacitor C
1
is not needed,
whereas in the second case a high value of C
1
(>
1
μ
F)
must be chosen. In fact, in this kind of application, C
1
has
to supply to the input pin the minimum allowed voltage
during the negative half wave. Obviously bigger C
1
value,
more constant the input voltage is and consequently
smaller the output voltage ripple. For the right choice of
the input capacitor, you have also to remember that
increasing its value you will obtain an increased power
dissipation, and a heatsink could be required. The right
heatsink is determined by the load current, input voltage
and ambient temperature. In case of pulse or A.C.
operation the junction temperature is limited by the
thermal capacitances since the package and the heatsink
masses
are able
to absorb heat.
temperature reaches the thermal shutdown limit the
output stage of the regulator is turned-off so that only the
biasing current of the device can flow into the input pin.
Thermal hysteresis is added just to prevent oscillations.
The device is able to provide minimum 40 mA for a time
that is function of dissipated power and consequently of
the used heatsink. In general the device is also suitable in
electronically
switched
motor
consumer equipments controls power supply or constant
current source.
If the
junction
housekeeping
supply,
APPLICATION EXAMPLE
The most common application for the device is in the DC/
DC converters with an input voltage up to 400 VDC and a
C
2
suggested value of 0,1
μ
F.
Using an external rectifier an AC/DC converter can be
easily implemented, in this case the device can operate
with an AC voltage up to 285VRMS. In this case must be
used a minimum 1
μ
F input capacitor to provide the load
current during the negative half cycle of the main. Another
important circuit that can be implemented is the start up
function for low voltage input PWM ICs directly from a
high voltage source (see figure 3).
V
OUT
V
IN
VB408
A
DJ
R1
R2
C2
C1
FC00420
V
IN
V
OUT
V
REF
相關PDF資料 |
PDF描述 |
|---|---|
| VB408FI | HIGH VOLTAGE LINEAR REGULATOR POWER I.C. |
| VB921ZVFI | High Voltage Ignition Coil Driver Power IC(高壓點火線圈驅動器，電源芯片) |
| VB921 | HIGH VOLTAGE IGNITION COIL DRIVER POWER I.C. |
| VB921Z | Ignition Circuit |
| VB921ZFI | Ignition Circuit |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| VB408FI | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:HIGH VOLTAGE LINEAR REGULATOR POWER I.C. |
| VB409 | 功能描述:線性穩(wěn)壓器 - 標準 Dual Out 5V/16V 1A RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
| VB409(022Y) | 制造商:STMicroelectronics 功能描述: |
| VB409(022Y)13TR | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| VB409-022Y | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:HIGH VOLTAGE REGULATOR POWER I.C. |
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