US3033 查看數據表（PDF） - Unisem
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US3033 Datasheet PDF : 9 Pages
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US3033
TYPICAL APPLICATION
5V to 3.3V for Pentium Application with AGP or Pentium II Application without ATX power supply
Dual mode Operation between Switching or Linear mode.
R13 C9
R9
12V
C8
8765
V12 Drv2 Vfb2 Gnd
U1
Drv1V12swVfb1 Vhyst
1234
C3
R10
R1A
R1B
R3
C5
Figure3- This unique application of US3033 allows the de-
signer to switch between Linear or Switching mode of
R6
operation using a single IC. This circuit has the flexibility
to be used for low current operation in Linear mode for
cost reasons and yet be able to operate in the Switching
R7
mode if the load current increases and the heat gener-
ated by the Linear operation will be an issue. Table below
descibes the components that will be effected for the
two modes of operation.
L2
Vout
L1
C7
5V
C1
Q2
C2
C4
R2 D1
R4
R5
3033app3-1.3
Note 1: For the applications where it is desirable to
eliminate the heat sink, the IRL3103S for Q2 and
MBR1545CT for D2 in TO263 packages with minimum of
1" square copper pad can be used.
Mode of Operation
Switching
Linear
L1 L2 D1 C4 C5
VV VVV
SS OOO
R1A R1B R2
OVV
V
OO
R3 R4 R5 R6 R7
V VV VO
O VO VV
V = See parts list for value S = Short O = Open
Ref Desig Description
U1
LDO/Switcher IC
Q2
MOSFET
D1
Schottky Diode
L2
Inductor
L1
R1A
R1B
R2
R3
R4
R5
R6
R7
R9
R10
R13
C1,2
C3
C4
C5
C7
C8
C9
HS1
Inductor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
Heat Sink
HS2 Heat Sink
Qty
Part #
1 US3033CS ( 8 pin SOIC)
1 IRL3303 (TO220)
IRL3103S (TO263) (note 1)
1 MBR1045CT (TO220)
MBRB1545CT (TO263) (note1)
1 Core:T50-18,L=4 uH
Turns: 10T, 18 AWG
1 L=2 uH
1 2.4k ohm,5%, SMT 1206 size
1 22 ohm,5%, SMT 1206 size
1 10 ohm, 5%, SMT 1206 size
1 249 kohm,1%, SMT 0805 size
1 1 kohm,1%, SMT 0805 size
1 576 ohm,1%, SMT 0805 size
1 180 ohm,1%, SMT 0805 size
1 100 ohm,1%, SMT 0805 size
1 10 ohm, 5%, SMT 1206 size
1 1k ohm, 5%, SMT 1206 size
1 7.5k ohm, 5%, SMT 1206 size
2 6MV1500GX, 1500uF,6.3V, Elect
1 1 uF,Ceramic, SMT 0805 size
1 470 pF,Ceramic, SMT 0805 size
1 10 pF,Ceramic, SMT 0805 size
1 6MV1500GX, 1500uF,6.3V, Elect
1 1 uF,Ceramic, SMT 0805 size
1 470pF,Ceramic, SMT 0805 size
1 For MOSFET in Switching mode , 577002
For MOSFET in Linear mode :
507222 (3.3V current<5A),
576602 (3.3V current< 3.5A)
1 For Schottky Diode , 577002
Manufacturer
Unisem
International
Rectifier
Motorola
Micro Metal
(core)
Sanyo
Sanyo
Sanyo
Sanyo
Aavid
Aavid
4-6
Rev. 1.5
1/14/99
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