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参数资料
| 型号： | PWS725 |
| 文件页数： | 5/6页 |
| 文件大小： | 66K |
| 代理商： | PWS725 |
5
PWS725A/726A
FIGURE 2. Synchronization of Multiple PWS725As or
PWS726As from a Master Converter.
FIGURE 3. Synchronization of Multiple PWS725As or
PWS726As from an External TTL Signal.
FIGURE 4. Frequency Adjustment Procedure.
OUTPUT CURRENT RATING
The total current which can be drawn from the PWS725A
or PWS726A is a function of total power being drawn from
both outputs (see Functional Diagram). If one output is not
used, then maximum current can be drawn from the other
output. If both outputs are loaded, the total current must be
limited such that:
|I
L
+| + |I
L
–|
≤
80mA
It should be noted that many analog circuit functions do not
simultaneously draw full rated current from both the posi-
tive and negatives supplies. For example, an operational
amplifier may draw 13mA from the positive supply under
16
PWS725A/726A
15
19
(1)
+7V to +18 V
16
PWS725A/726A
15
19
(1)
To Other
PWS725A/726A
Converters
NOTES: (1) Units to be synchronized
should have a lower free-running
frequency than the TTL signal.
Grounding Frequency Adjust (Pin 19)
will shift the free-running frequency
to approximately 400kHz. (2) The TTL
SYNC signal can have a frequency
range of 450kHz to 1.5MHz.
2N3904
2N3904
3
8
4
1
2
TTL
SYNC
Signal
(2)
MC1472
or Equivalent
Peripheral
Driver
620
100
1/8W
+5V
330
1W
15
20
PWS725A/726A
19
20k
(1)
Frequency
Increase
Monitor frequency with scope
or frequency counter (use
low C probe).
+5V
BE
+4V
BE
1.25μs Nominal
SYNC Signal
NOTE: (1) For nominal 800kHz operation, leave
pins 19 and 20 open.
15
4
16
Master
PWS725A
Buffer
–V
CC
+V
CC
OPA633
8
Keep Connection
Short
16
Slave
PWS725A/726A
15
19
(1)
+7V to +18 V
16
15
19
(1)
To Other
PWS725A/726A
Converters
NOTE: (1) Units to be synchronized
should have a lower free-running
frequency than the master unit.
Grounding Frequency Adjust (pin 19)
will shift the free-running frequency
to approximately 400kHz.
Slave
PWS725A/726A
switches operating in their safe operating area under fault
conditions or excessive loads. When either of these condi-
tions occur, the peak input current exceeds a safe limit. The
result is an approximate 5% duty cycle, 300
μ
s drive period
to the MOSFET switches. This protects the internal MOSFET
switches as well as the external load from any thermal
damage. When the fault or excessive load is removed, the
converter resumes normal operation. A delay period of
approximately 50
μ
s incorporated in the current sensing
circuitry allows the output filter capacitors to fully charge
after a fault is removed. This delay period corresponds to a
filter capacitance of no more than 1
μ
F at either of the output
pins. This provides full protection of the MOSFET switches
and also sufficiently filters the output ripple voltage (see
specification table). The current sensing circuitry is de-
signed to provide thermal protection for the MOSFET
switches over the operating temperature range as well. The
low thermal resistance for the package (
θ
= 10
°
C/W)
ensures safe operation under rated conditions. When these
rated conditions are exceeded, the unit will go into its
shutdown mode.
An optional potentiometer can be connected between the
two FREQUENCY ADJUST pins to trim the oscillator
operating frequency
±
10% (see Figure 4). Care should be
taken when trimming the frequency near the low frequency
range. If the frequency is trimmed too low, the peak induc-
tive currents in the primary will trip the input current
sensing circuitry to protect the MOSFET switches from
these peak inductive currents.
The ENABLE pin allows external control of output power.
When this pin is pulled low, output power is disabled. Logic
thresholds are TTL compatible. When not used, the Enable
input may be left open or tied to V
IN
(pin 16).
相关PDF资料 |
PDF描述 |
|---|---|
| PWS725A | Isolated, Unregulated DC/DC Converters(隔离，非稳压 DC/DC变换器) |
| PWS726A | Isolated, Unregulated DC/DC Converters(隔离，非稳压 DC/DC变换器) |
| PWS750-1U | Isolated, Unregulated DC/DC CONVERTER COMPONENTS |
| PWS750-2U | Isolated, Unregulated DC/DC CONVERTER COMPONENTS |
| PWS750-3U | Isolated, Unregulated DC/DC CONVERTER COMPONENTS |
相关代理商/技术参数 |
参数描述 |
|---|---|
| PWS725A | 制造商:BB 制造商全称:BB 功能描述:Isolated, Unregulated DC/DC CONVERTERS |
| PWS725A/PWS726A | 制造商:未知厂家 制造商全称:未知厂家 功能描述:PWS725A. PWS726A - DISCONTINUED PRODUCT. No longer recommended for new design. |
| PWS726A | 制造商:BB 制造商全称:BB 功能描述:Isolated, Unregulated DC/DC CONVERTERS |
| PWS727 | 制造商:BB 制造商全称:BB 功能描述:DC-DC变换器,Isolated, Unregulated DC/DC CONVERTERS |
| PWS727/PWS728 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:PWS727. PWS728 - DISCONTINUED PRODUCT. No longer recommended for new design. |
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