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参数资料
| 型号： | AS2850AU-2.5 |
| 元件分类： | 固定正电压单路输出LDO稳压器 |
| 英文描述： | 2.5 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSFM3 |
| 封装： | TO-220, 3 PIN |
| 文件页数： | 3/6页 |
| 文件大小： | 159K |
| 代理商： | AS2850AU-2.5 |
Rev. 10/11/00
AS2850
APPLICATION HINTS
The AS2850 incorporates protection against over-current
faults, reversed load insertion, over temperature operation, and
positive and negative transient voltage. However, the use of
an output capacitor is required in order to insure the stability
and the performances.
Stability
The output capacitor is part of the regulator’s frequency
compensation system. Either a 22
F aluminum electrolytic
capacitor or a 10
F solid tantalum capacitor between the
output terminal and ground guarantees stable operation for all
operating conditions.
However, in order to minimize overshoot and undershoot, and
therefore optimize the design, please refer to the section
‘Ripple Rejection’.
Ripple Rejection
Ripple rejection can be improved by adding a capacitor
between the ADJ pin and ground. When ADJ pin bypassing is
used, the value of the output capacitor required increases to its
maximum (220
F for an aluminum electrolytic capacitor, or
47
F for a solid tantalum capacitor). If the ADJ pin is not
bypass, the value of the output capacitor can be lowered to
10
F for an electrolytic aluminum capacitor or 4.7F for a
solid tantalum capacitor.
However the value of the ADJ-bypass capacitor should be
chosen with respect to the following equation:
C = 1 / ( 6.28 * FR * R1 )
Where C
= value of the capacitor in Farads (select an
equal or larger standard value),
FR
= ripple frequency in Hz,
R1
= value of resistor R1 in Ohms.
If an ADJ-bypass capacitor is use, the amplitude of the output
ripple will be independent of the output voltage. If an ADJ-
bypass capacitor is not used, the output ripple will be
proportional to the ratio of the output voltage to the reference
voltage:
M = VOUT / VREF
Where M
= multiplier for the ripple seen when the ADJ pin
is optimally bypassed.
VREF = Reference Voltage
Reducing parasitic resistance and inductance
One solution to minimize parasitic resistance and inductance is
to connect in parallel capacitors.
This arrangement will
improve the transient response of the power supply if your
system requires rapidly changing current load condition.
Thermal Consideration
Although the AS2850 offers some limiting circuitry for
overload conditions, it is necessary not to exceed the
maximum junction temperature, and therefore to be careful
about thermal resistance. The heat flow will follow the lowest
resistance path, which is the Junction-to-case thermal
resistance. In order to insure the best thermal flow of the
component, a proper mounting is required. Note that the case
of the device is electrically connected to the output. In case
the case has to be electrically isolated, a thermally conductive
spacer can be used. However do not forget to consider its
contribution to thermal resistance.
Assuming:
VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 50
°C/W,
θHeatsink Case= 6°C/W, θHeatsink Case = 0.5°C/W, θ JC = 3°C/W
Power dissipation under this condition
PD = (VIN – VOUT) * IOUT = 7.5W
Junction Temperature
TJ = TA + PD * (
θCase – HS + θ HS θ JC)
For the Control Section
TJ = 50 + 7.5*(0.5 + 6=3) = 121.25
°C
121.25
°C < TJ (max) for the Control & Power Sections.
In both case reliable operation is insured by adequate junction
temperature.
相关PDF资料 |
PDF描述 |
|---|---|
| AS2850AU-3.3 | 3.3 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSFM3 |
| AS2850AU-5.0 | 5 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSFM3 |
| AS2850T-1.5 | 1.5 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSSO2 |
| AS2850T-3.3 | 3.3 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSSO2 |
| AS2850T-5.0 | 5 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSSO2 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AS2850AU-3.3 | 制造商:Alpha & Omega Semiconductor 功能描述: 制造商:Alpha & Omega Semiconductor 功能描述:3.3 V FIXED POSITIVE LDO REGULATOR, 1.2 V DROPOUT, PSFM3 |
| AS2850AU-5.0 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Analog IC |
| AS2850T | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Positive Adjustable Voltage Regulator |
| AS2850T-1.5 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Analog IC |
| AS2850T-2.5 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Analog IC |
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