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參數(shù)資料
| 型號： | PWS745 |
| 英文描述： | 272 POS 1.27MM PITCH BGA SOCKET |
| 中文描述： | 多通道隔離DC / DC變換器元件 |
| 文件頁數(shù)： | 6/10頁 |
| 文件大小： | 83K |
| 代理商： | PWS745 |
6
PWS745
COM1, COM2
The COM pins are connected to the sources of the internal
MOSFETs and each pin must be tied to ground. The current
from the primary windings of the transformers flows in
through the T and T pins and then out through the COM
pins.
TTL
IN
This pin must be tied to ground, except when it is desired to
control the driver frequency with an external TTL level
frequency source. The duty cycle can vary from 12% to 95%
(see Typical Performance Curves). The input frequency
must be twice the desired operating frequency, because an
internal flip-flop is used to produce a precise 50% duty cycle
signal to the drivers.
TTL
OUT
When multiple PWS745-1 drivers must be synchronized to
minimize beat frequencies in the output, a single driver is
used to synchronize with the remaining drivers. The TTL
pin is used as the synchronizing signal from the master
controller and is connected to the TTL
of the slave drivers.
A standard open collector output is provided, therefore a
FIGURE 1. Typical Connections.
TRANSFORMER
ISOLATION
CHANNELS
I/O
TECHNOLOGY
PWS745-2
PWS745-4
PWS740-2
PWS750-2U
PWS750-4U
750VAC
750VAC
1500VAC
750VAC
750VAC
8
4
8
8
4
1:1
1:3
1:1
1:1
1:3
Thru-hole
Thru-hole
Thru-hole
Surface-mount
Surface-mount
TABLE I.
DIODE BRIDGE
TECHNOLOGY
PWS740-3
PWS750-3U
Thru-hole
Surface-mount
TABLE II.
BASIC OPERATION
The PWS745 components are used to build a multichannel
DC/DC converter. The oscillator runs at 600kHz nominal,
making it possible to reduce the size of the transformer and
lower the output ripple voltage. The PWS745-1 is a power
oscillator/switch able to directly drive the primary side of an
isolation transformer. The small size of the driver is achieved
by using a multiple chip transfer molding process. The
power components are mounted directly on the copper
leadframe, utilizing two pins directly connected to each die
pad to maximize heat sink area. The output of the trans-
former is rectified with a high speed diode bridge. The
PWS740-2 is used when 1500Vrms isolation is required.
The PWS745-2 or PWS750-2 is used when 750Vrms isola-
tion is required. With these transformers, the output voltages
directly track the input voltage. The PWS745-4 or PWS750-
4 is used to step up the input voltage from 5V to
±
15V.
Operation at 5V makes it possible to build an isolated system
for powering the analog components when only a logic
supply is available. Using the PWS745-2 or -4 allows the
user 0.5in. PCB spacing. The possible component combina-
tions are summarized in Figure 1 and Tables I and II. The
600kHz operating frequency enables direct synchronization
with products such as the ISO120 and ISO121. See Figure
3. The use of synchronization makes it possible to eliminate
any power-supply induced ripple in the output of the isola-
tion amplifiers and to minimize beats falling in the signal
path bandwidth.
PIN DESCRIPTIONS
+V
IN
AND GND
The +V
pin supplies power to the oscillator. The GND pins
are used for the return currents of the driver chip.
Driver
Oscillator
Soft
Start
TTL
TTL
GND
+V
DRIVE
GATE
IN
OUT
IN
DRIVE
GATE
4
0.3μF
0.3μF
+V
OUT
–V
OUT
0.3μF
GND1
4
1
3
6
GND
AC
AC
0.3μF
0.3μF
+V
OUT
–V
OUT
0.3μF
GND2
4
1
3
6
GND
AC
AC
T
O
V
D
T
O
T
O
V
D
T
O
COM1
COM2
T
T
Transformer
(See Table I)
Diode Bridge
(See Table II)
0.1μF
EN
+V
IN
20μH
(1)
NOTE: (1) Optional input filter inductor and
capacitor to reduce input current ripple.
Multiple Channels
(See Table I)
PWS745-1
(1)
10μF
11
10
9
12
13
16
14, 15
1
2, 3
5
8
7
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PWS745A/PWS726A/PWS740 WAF | 制造商:Texas Instruments 功能描述: |
| PWS745A/PWS726A/PWS741 WAF | 制造商:Texas Instruments 功能描述: |
| PWS745A/PWS726A/PWS742 WAF | 制造商:Texas Instruments 功能描述: |
| PWS745A/PWS726A/PWS743 WAF | 制造商:Texas Instruments 功能描述: |
| PWS745A/PWS726A/PWS744 WAF | 制造商:Texas Instruments 功能描述: |
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