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参数资料
| 型号： | PWS750-3U |
| 英文描述： | Isolated, Unregulated DC/DC CONVERTER COMPONENTS |
| 中文描述： | 隔离，稳压直流/直流转换器元件 |
| 文件页数： | 5/11页 |
| 文件大小： | 151K |
| 代理商： | PWS750-3U |
PWS750
5
THEORY OF OPERATION
The PWS750 components are basic building blocks to be
used with other standard components to build an isolated
push-pull DC/DC converter. The oscillator runs at 800kHz
nominal, making it possible to reduce the size of the trans-
former and lower the output ripple voltage.
PWS750-1U OSCILLATOR PIN FUNCTIONS
TTL
IN
is used to control the driver frequency with an
external TTL level frequency source. The input frequency
must be twice the desired driver frequency, since there is an
internal divide-by-2 circuit to produce a 50% duty cycle
output. The input duty cycle can vary from 12% to 95% (see
Typical Performance Curves). When in the free running
mode, the TTL
IN
pin must be tied to ground.
TTL
OUT
is used when it is desired to synchronize the outputs
of multiple PWS750-1Us to minimize beat frequency prob-
lems. A standard open collector output is provided, therefore
a 330
to 3.3k
pull-up resistor will be necessary depend-
ing on stray capacitance on the sync line. A maximum of
eight PWS750-1Us can be connected without the use of an
external TTL buffer.
An Enable pin is provided so that the driver (T, T) can be
shut down to minimize power use if required. A TTL low
applied to the pin will shut down the driver within one cycle.
A TTL high will enable the driver within one cycle. The
TTL
OUT
will still have an 800kHz signal when a master
driver is disabled, so other synchronized drivers will not be
shut down. The pin can be left open for normal operation.
The +V
IN
pin supplies power to the oscillator. The V
D
pin
connects the power to the transformer through the internal
overcurrent sense resistor. The other end of the overcurrent
sense resistor is tied to +V
IN
. A 0.3
μ
F bypass capacitor must
be connected to the V
D
pin to reduce the ripple current
through the shunt resistor; otherwise false current limit
conditions can occur due to ripple voltage peaks.
TYPICAL PERFORMANCE CURVES
(CONT)
T
A
= +25
°
C, V
IN
= 15VDC, I
LOAD
=
±
15mA unless otherwise noted.
During overload conditions the output drive shuts off for
approximately 80
μ
s, then turns back on for 20
μ
s, resulting
in a 25% power up duty cycle. If the overload condition still
exists, then the output will shut off again. When the fault or
the excessive load is removed, the converter resumes normal
operation.
The T and T pins are the complementary FET drive outputs
and are tied directly to the corresponding FET gate. The
connection must be as short as possible. For multiple chan-
nel operation they cannot be located above any ground or
power planes, because capacitive loading will not allow fast
enough charging of the FET gate.
PWS750-2U AND PWS750-4U
TRANSFORMER PIN FUNCTIONS
On the primary side the V
D
pin of the PWS750-2U is tied
directly to the V
D
pin of the PWS750-1U. Remember to
place a 0.1
μ
F capacitor as close to the PWS750-2U V
D
pin
as possible. The T
O
and T
O
pins are connected to the drains
of the corresponding FETs, whose sources are connected to
ground. On the secondary side of the transformer, the Gnd
pin is tied directly to the isolated ground. AC pins are
800kHz square wave signals at twice the output voltage, and
are connected directly to the corresponding pin on the
PWS750-3U. Pins 2 and 4 can be interchanged for ease of
hook up. The connection to the diode bridge must be as
direct as possible to minimize radiated noise.
The winding ratio for the PWS750-2U is 1:1. This means
that the output would normally be less than the input due to
voltage drops in the FETs, transformer and diode bridge.
Since the DC/DC converter is operating at 800kHz, the
transformer is starting to operate close to the resonant
frequency, which causes the output to increase in magni-
tude.
OUTPUT VOLTAGE DRIFT WITH A ±15mA LOAD
15.5
15.25
15
14.75
14.5
–25
0
25
50
75
100
Temperature (°C)
V
O
TTL
IN
Frequency (MHz)
1.5
1.6
2
1
16
15
±
O
THE OUTPUT VOLTAGE CAN BE ADJUSTED
±3% BY VARYING THE DRIVER FREQUENCY
14
15.5
14.5
相关PDF资料 |
PDF描述 |
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| PWS750-4U | Isolated, Unregulated DC/DC CONVERTER COMPONENTS |
| PWS750 | |
| PWS750 | Isolated, Unregulated DC/DC Converters Components(隔离的未调整的 DC/DC变换器) |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| PWS750-4U | 制造商:BB 制造商全称:BB 功能描述:Isolated, Unregulated DC/DC CONVERTER COMPONENTS |
| PWS7702A230N4LG | 制造商:Hammond Manufacturing 功能描述:AIR/WATER HEAT EXCHANGER |
| PWS-781-1S | 制造商:SUPER MICRO COMPUTER, INC. 功能描述:BPN,PWS,SNK,FAN - Trays |
| PWS-801-1R | 制造商:Supermicro Computer Inc 功能描述:Power Supply 制造商:SUPER MICRO COMPUTER, INC. 功能描述:1U, 800W, 12V, REDUNDANT MODULE - Bulk |
| PWS-865-PQ | 制造商:Supermicro Computer Inc 功能描述:SUPERCHASSIS 制造商:Supermicro Computer Inc 功能描述:BPN,PWS,SNK,FAN - Trays |
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