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参数资料
| 型号： | AFL27003R3S |
| 厂商： | International Rectifier |
| 英文描述： | HIGH RELIABILITY HYBRID DC/DC CONVERTER |
| 中文描述： | 高可靠性的混合式DC / DC转换器 |
| 文件页数： | 7/9页 |
| 文件大小： | 158K |
| 代理商： | AFL27003R3S |
www.irf.com
7
AFL27003R3S
R
= 100
-
-.025
adj
NOM
V
V
OUT
V
NOM
Where
V
NOM
= device nominal output voltage, and
V
OUT
= desired output voltage
Figure V. Connection for V
OUT
Adjustment
Input Filter
Undervoltage Lockout
A minimum voltage is required at the input of the converter
to initiate operation. This voltage is set to 150
±
5 volts. To
preclude the possibility of noise or other variations at the
input falsely initiating and halting converter operation, a
hysteresis of approximately 10 volts is incorporated in this
circuit. Thus if the input voltage droops to 140
±
4 volts, the
converter will shut down and remain inoperative until the
input voltage returns to
≈
150 volts.
The AFL270XXS series converters incorporate a LC input
filter whose elements dominate the input load impedance
characteristic at turn-on. The input circuit is as shown in
Figure IV.
Figure IV. Input Filter Circuit
Output Voltage Adjust
In addition to permitting close voltage regulation of remotely
located loads, it is possible to utilize the converter sense
pins to incrementally increase the output voltage over a
limited range. The adjustments made possible by this method
are intended as a means to “trim” the output to a voltage
setting for some particular application, but are not intended
to create an adjustable output converter. These output
voltage setting variations are obtained by connecting an
appropriate resistor value between the +sense and -sense
pins while connecting the -sense pin to the output return pin
as shown in Figure V. below. The range of adjustment and
corresponding range of resistance values can be determined
by use of the following equation.
Finding a resistor value for a particular output voltage, is
simply a matter of substituting the desired output voltage
and the nominal device voltage into the equation and solving
for the corresponding resistor value.
Caution: Do not set R
adj
< 500
Attempts to adjust the output voltage to a value greater than
120% of nominal should be avoided because of the potential
of exceeding internal component stress ratings and
subsequent operation to failure. Under no circumstance
should the external setting resistor be made less than 500
.
By remaining within this specified range of values, completely
safe operation fully within normal component derating limits
is assured.
Examination of the equation relating output voltage and
resistor value reveals a special benefit of the circuit topology
utilized for remote sensing of output voltage in the
AFL270XXS series of converters. It is apparent that as the
resistance increases, the output voltage approaches the
nominal set value of the device. In fact the calculated limiting
value of output voltage as the adjusting resistor becomes
very large is
≈
25mV above nominal device voltage.
The consequence is that if the +sense connection is
unintentionally broken, an AFL270XXS has a fail-safe output
voltage of Vout + 25mV, where the 25mV is independent of
the nominal output voltage. It can be further demonstrated
that in the event of both the + and - sense connections
being broken, the output will be limited to Vout + 440mV.
This 440 mV is also essentially constant independent of the
nominal output voltage. While operation in this condition is
not damaging to the device, not at all performance
parameters will be met.
8.4μH
Pin 1
Pin 2
0.54μfd
Enable 2
Share
+ Sense
- Sense
Return
+ V
out
To Load
R
ADJ
AFL270xxS
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相关代理商/技术参数 |
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|---|---|
| AFL27003R3SW | 制造商:International Rectifier 功能描述:DC/DC CONVERTER, MINIMUM SCREENING - Bulk |
| AFL27003R3SW/CH | 制造商:International Rectifier 功能描述:DC/DC CONVERTER, CLASS H - Bulk |
| AFL27003R3SW/ES | 制造商:International Rectifier 功能描述:DC/DC CONVERTER, ENVIRONMENTAL SCREENING - Bulk |
| AFL27003R3SW/HB | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGH RELIABILITY HYBRID DC/DC CONVERTER |
| AFL27003R3SX | 制造商:International Rectifier 功能描述:DC/DC CONVERTER, MINIMUM SCREENING - Bulk |
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