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参数资料
| 型号： | AFL2809SX |
| 厂商： | International Rectifier |
| 英文描述： | ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS |
| 中文描述： | 先进的模拟高可靠性的混合式DC / DC变换器 |
| 文件页数： | 8/16页 |
| 文件大小： | 445K |
| 代理商： | AFL2809SX |
8
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AFL270XXS Series
The AFL270XXS series converters incorporate a single
stage LC input filter whose elements dominate the input
load impedance characteristic during the turn-on sequence.
The input circuit is as shown in Figure IV.
Figure IV. Input Filter Circuit
8.4μH
Pin 1
Pin 2
0.54μfd
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 hys-
teresis of approximately 10 volts is incorporated in this cir-
cuit. Thus if the input voltage droops to 140
±
5 volts, the
converter will shut down and remain inoperative until the
input voltage returns to
≈
150 volts.
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 deter-
mined by use of the equation presented below.
R
= 100
-
-.025
adj
NOM
V
V
OUT
V
NOM
Where
V
NOM
= device nominal output voltage, and
V
OUT
= desired output voltage
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 solv-
ing for the corresponding resistor value.
Figure V. Connection for V
OUT
Adjustment
Enable 2
Share
+ Sense
- Sense
Return
+ V
out
To Load
R
ADJ
AFL270xxS
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 poten-
tial of exceeding internal component stress ratings and sub-
sequent 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 is
assured.
Examination of the equation relating output voltage and re-
sistor 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 limit-
ing value of output voltage as the adjusting resistor be-
comes very large is
25mV above nominal device voltage.
The consequence is that if the +sense connection is un-
intentionally 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 all performance parameters
will be met.
Typical performance data is graphically presented on the follow-
ing pages for selected parameters on a variety of AFL270XXS
type converters. The data presented was selected as repre-
sentative of more critical parameters and for general interest in
typical converter applications.
Input Filter
Undervoltage Lockout
Output Voltage Adjust
Performance Data
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| AFL2809SY | ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS |
| AFL2809SZ | ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AFL2809SX/CH | 制造商:IRF 制造商全称:International Rectifier 功能描述:ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS |
| AFL2809SX/ES | 制造商:IRF 制造商全称:International Rectifier 功能描述:28V Input, Single Output HYBRID-HIGH RELIABILITY DC/DC CONVERTER |
| AFL2809SX/HB | 制造商:IRF 制造商全称:International Rectifier 功能描述:28V Input, Single Output HYBRID-HIGH RELIABILITY DC/DC CONVERTER |
| AFL2809SXCH | 制造商:IRF 制造商全称:International Rectifier 功能描述:270V Input, Single Output |
| AFL2809SX-CH | 制造商:IRF 制造商全称:International Rectifier 功能描述:ADVANCED ANALOG HIGH RELIABILITY HYBRID DC/DC CONVERTERS |
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