參數(shù)資料
型號: DPA423P
廠商: POWER INTEGRATIONS INC
元件分類: 穩(wěn)壓器
英文描述: 1.75 A SWITCHING REGULATOR, 425 kHz SWITCHING FREQ-MAX, PDIP8
封裝: PLASTIC, MS-001AB, DIP-8
文件頁數(shù): 8/36頁
文件大?。?/td> 705K
代理商: DPA423P
Rev. S 12/07
16
DPA422-426
www.powerint.com
Figure 27. PoE Interface Circuit Using a Bipolar Transistor Pass-Switch and DPA424P.
U1
DPA424P
D6
BAV
19WS
Q22
Si4804
D21
SL13
15 V
Q21
Si4804
C2
1
μF
100 V
VR1
SMAJ
150
C5
47
μF
10 V
D41
BAV19WS
D31
20CJQ060
R21
10
Ω
R22
10
Ω
R23
10 k
Ω
VR21
C21
2.2 nF
U2
T1
R1
649 k
Ω
1%
R3
1.0
Ω
C22-C24
100
μF 5 V
VR41
6.8 V
D42
IN4148
C31
100
μF
10 V
C41
4.7
μF, 35 V
C25
1
μF
10 V
L1
1
μH 2.5 A
PoE Interface
L2
16
μH 4 A
C6
4.7
μF
20 V
D11
BAV19WS
U3
LM431AIM3
C11
2.2
μF
10 V
R14
1 k
Ω
R15
10 k
Ω
1%
R16
10 k
Ω
1%
R4
160
Ω
R12
150
Ω
R13
11
Ω
C1
1
μF
100 V
U2
PC357
N1T
R11
10 k
Ω
PI-3824-040706
DPA-Switch
5 V, 2.4 A
RTN
7.5 V, 0.4 A
20 V, 10 mA
C13
68 nF
4
5
3
6
7
18
72
7
8
6
5
43
Ethernet
(RJ-45)
Connector
R2
13.3 k
Ω
1%
R52
20 k
Ω
D101
DL4002
D102
D103
DL4002
D104
D105
DL4002
D106
D107
DL4002
D108
R22
10 k
Ω
R23
174 k
1%
R21
10 k
R51
24.9 k
Ω
1% 1/4 W
D51
BAV19
D52
BAV19
C51
1 nF
50 V
R54
20
Ω
VR51
28 V
(1,2)
(4,5)
(3,6)
(7,8)
D
S
C
L
F
X
CONTROL
C12
100 nF
R53
20 k
Ω
Q51
TIP29C (100 V/1 A)
or MMBTA06
C4
220 nF
Q20
MMBTS3906
controlled pass-switch. By adding this circuitry to the front end
of a DPA converter, a low cost and low component count PoE
powered device (PD) power supply can be implemented.
Figure 27 shows a typical PD solution.
The PoE specication requires the PD to provide three
fundamental functions: discovery, classication, and pass-
switch connection.
When input voltage is applied to the PD, it must present the
correct discovery signature impedance in the voltage range of
2.5 VDC to 10 VDC. This impedance is provided by R51 in
Figure 27.
The second “classication” phase occurs at input voltages
15 VDC to 20 VDC. The PD must draw a specied current to
identify the device class (Class 0 species 0.5 mA to 4 mA).
This is again accomplished by resistor R51.
In the third phase, the bipolar pass-switch (Q51 in Figure 27)
connects the input voltage to the power supply at voltages
above approximately 30 VDC (28 V+VR52). Zener diode VR51
conducts, driving the current through resistor R52 to the base
of Q51. Resistor R53 prevents turn-on under other conditions.
Once the Power supply has started, components D51, D52,
C51 and R54 enhance the base-current drive by coupling
power from the power supply bias winding.
Once the three start up phases have been successfully
completed, the DPA-Switch is allowed to function as a forward
converter (described in Figure 25 and accompanying text).
Key Application Considerations
DPA-Switch Design Considerations
Power Table
This section provides a description of the assumptions used to
generate the power tables (Tables 1 and 3 through 6) and
explains how to use the information provided by them.
All Power tables: Tables 1 and 3 through 6
Maximum output power is limited by the device internal
current limit. This is the peak output power which could
become the continuous output power, provided adequate
heat sinking is used.
Data assumes adequate heat sinking to keep the junction
temperature at or below 100
°C and worst case R
DS(ON) at
T
J = 100 °C.
The use of P and G packages are recommended for device
dissipation equal to or less than 1.5 W only due to package
thermal limitation. For device dissipation above 1.5 W, use
R package.
相關(guān)PDF資料
PDF描述
DPAF-08-03.0-H-8-1-A 96 CONTACT(S), FEMALE, STRAIGHT BOARD STACKING CONNECTOR, SURFACE MOUNT
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