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參數(shù)資料
| 型號： | BBF2805SE |
| 英文描述： | Analog IC |
| 中文描述： | 模擬IC |
| 文件頁數(shù)： | 6/7頁 |
| 文件大?。?/td> | 163K |
| 代理商： | BBF2805SE |
BBF2800S SERIES
APPLICATION
INFORMATION
OUTPUT ADJUST / COMP
The output voltage of the BBF2800S may be adjusted from
90% to 110% of nominal value by the use of a 50K
potenti-
ometer as shown. Adjustment beyond this range is possible
however certain characteristics of the converter such as but
not limited to input voltage range, efficiency, ripple and tem-
perature performance will change. Characterization by the
user is recommended in such applications.
Adjust/comp (pin 4) may be driven by external circuitry
referenced to pin 8 (-output sense) if desired. Grounding pin
4 causes output voltage to increase (25% typically) while
driving pin 4 above 1.3 V causes output voltage to decrease.
Pin 4 may be driven through 10K
or more if connection of the
comp function is also required.
The comp function of pin 4 allows transient response and
phase margin to be tailored to suit a specific application. This
feature may be utilized by connecting a small (1-500 nf)
capacitor between pins 4 and 6 or 7. This is generally recom-
mended when very large low ESR load capacitances are
used.
SHUTDOWN PLUS
Pin 2 is used for remote shutdown, output fault detection,
and/or setting the input voltage point at which the converter
will turn on as shown in the typical application diagram. No
connection to pin 2 is necessary for normal operation of the
converter. Pin 2 is referenced to pin 12 (-input).
Shutdown may be implemented by simply connecting pin 2
to an open collector logic output or switch rated at 2.5 mA, 25
Vdc or higher.
Input voltage turn on point is programmed with a single
resistor from pin 2 to 12. An input turn on/off hysteresis
(typically 3.5% of Vin) will be observed. This should be
considered when making or verifying set point adjustment.
The value of the setpoint resistor may be determined by the
following:
210 10
3
E
TO
– 9.5
R =
(±10% accuracy at 25°C)
Set point temperature coefficient is typically +400ppm/°C.
Output fault monitoring is accomplished by observing pin 2
with a high impedance monitoring circuit. Pin 2 voltage drops
from over 10 V to below 1 V when a load fault causes the
converters fault protection circuitry to activate. It will remain
low for at least 100 mS and return high. If the load fault is still
present pin 2 will return low and the cycle will repeat. If there
is no input setpoint programming resistor already in place a
resistor > 400 K
from pin 2 to 12 will provide pin 2 pull down.
MULTIPLE CONVERTER SYNCHRONIZATION
Synchronized operation of up to three BBF2800S series
converters may be accomplished without external compo-
nents. One unit selected to be the master is connected
normally with pin 10 grounded. The clock output pin 3 will
provide the sync signal for up to two slave units. The slave
units have pin 10 not connected and receive the clock signal
into pin 11. The clock signal lines may be shielded to prevent
radiation. A separate 50 ohm coax to each slave unit is
recommended in order to preserve signal integrity. Shield
ends should be connected to pin 12 of the nearest converter.
BBF2800S converters may also be synchronized to an
external 500 KHz (+/- 5%) frequency source driving pin 11 of
the converters. Pin 10 is not connected. The converters
synchronize to the positive edge of the frequency source
allowing a variety of wave forms (pulse, square, spike) to be
used. Pin 11 is internally capacitively coupled allowing unipo-
lar or bipolar frequency sources to be used. The source should
have a waveform rise time of 20 ns or less and be capable of
driving at least 4 volts peak into each 50 ohm pin 11 input (50
volts peak max).
An externally synchronized unit may be used to synchronize
other (slave) units. The slave units may be used in turn to
synchronize other slave units from their pin 3 outputs. Each
“generation” of slave units has a delay (100-200ns typical)
from the unit that it is synchronizing to.
4
7
8
50K
TYPICAL APPLICATION
The above diagram shows the remote sense feature which
reduces Vo errors due to the resistance of the conductors
feeding the load. This diagram also shows the connections for
non-synchronized operation (TIMING 1 and 2) as well as
output voltage trim, remote shutdown, fault monitoring, and
input voltage turn on point adjustment.
Rev. - 3/01
6
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相關(guān)代理商/技術(shù)參數(shù) |
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| BBF2805SH | 制造商:MSK 制造商全稱:M.S. Kennedy Corporation 功能描述:20W DC-DC CONVERTERS |
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| BBF2812E | 制造商:MSK 制造商全稱:M.S. Kennedy Corporation 功能描述:20W DC-DC CONVERTERS |
| BBF2812H | 制造商:MSK 制造商全稱:M.S. Kennedy Corporation 功能描述:20W DC-DC CONVERTERS |
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