MIC4681
Micrel
Applications Circuits*
For continuously updated circuits using the MIC4681, see Application Hint 37 at www.micrel.com.
C5
D3
1N4148
220nF
J2
J1
R1
5V ±2%
U1 MIC4681
L1
+30V max.
0.100Ω
800mA ±5%
2
1
3
4
IN
SW
C4
10nF
100µH
R7
4.99k
C2
100nF
C1
22µF
35V
J3
GND
C3
220µF
OFF
ON
D1
SHDN
GND
FB
MMBR140LT3
10V
S1
NKK G12AP
D2
4
5
2
R2
1N4148
lphone
3.01k
e
T
SOP-8
5–8
R4
U2
16.2k
3
R3
976Ω
U3
MIC6211BM5
R5
221k
LM4041DIM3-1.2
Ceular
o
T
R6
10k
J4
GND
Figure 7. Constant Current and Constant Voltage Battery Charger
J1
J3
U1 MIC4681
L1
+12V
GND
2
1
3
4
IN
SW
33µH
C3
0.022µF
50V
R1
8.87k
C4
68µF
20V
C5
33µF
35V
C1
68µF
20V
C2
0.1µF
SHDN
FB
D1
R2
1k
GND
5–8
ES1B
1A 100V
J4
SOP-8
–12V/150mA
J2
GND
Figure 8. +12V to –12V/150mA Buck-Boost Converter
+4.5V to +17V
U2
MIC4417BM4
3
Q1
* ISAT = 7.5A
U1 MIC4681
IN SW
Si4425DY
L1*
2
R2
20mΩ
C1
100µF
20V
C6
3.3V/5A
0.1µF
50µH
C4
50V
1
4
SHDN
GND
FB
C2
C3
470µF
6.3V
1000pF
D1
5A
SHUTDOWN
ENABLE
470µF
R1
R3
1k
1%
R4
1k
1%
R7
3.01k
1%
6.3V
1k
SOP-8
5–8
1%
C5
0.1µF
R6
16k 1%
D2
1N4148
U3
R8
R5
16k
1%
MIC6211BM5 1.78k
1%
GND
Figure 9. 5V to 3.3V/5A Power Supply
* See Application Hint 37 at www.micrel.com for bills of material.
February 2001
15
MIC4681
MICREL [ MICREL SEMICONDUCTOR ]
