LM2576-5.0TR 查看數據表（PDF） - Semtech Corporation
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LM2576-5.0TR Datasheet PDF : 19 Pages
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POWER MANAGEMENT
Applications Information - Inverting Buck/Boost
LM2575 & LM2576
CIN
D1
L1
COUT
IOUT
LM2575
47µF
3A
100µH
2,700µF
250mA
LM2576
100µF
7A
68µH
6,800µF
500mA
CIN
D1
L1
COUT
IOUT
LM2575
47µF
3A
100µH
470µF
100mA
LM2576
100µF
7A
68µH
2,700µF
750mA
Inverting buck/boost operation is a different topology of
operation than buck. This difference reduces the output
current capability of the device, in that the inductor must
supply all of the load current during the time the power
switch is off. Maximum output current is approximately:
Component stress requirements are very similar to the
buck with a few exceptions:
(1) catch diode breakdown VBR must be greater than
VIN + |VOUT|
IOUT
≈
2
3.5
1 +
VO
VIN
(LM2576 )
IOUT
≈
2
1.3
1 +
VO
VIN
(LM2575 )
(2) input capacitor is larger due to the increased peak
current during switch turn on. Power dissipation is
approximately:
PD
≈
VO
V O + VIN
IO
1
+
VO
V IN
V SAT
+ 0 .02 VIN
VO
V IN
Please contact factory for additional assistance when
using the buck/boost topology.
ã 2001 Semtech Corp.
15
www.semtech.com
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