Application Hint 43c

Application Hint 43c
Micrel
Application Hint 43c
89% Efficient RF Bias Circuit
by William Mai
Circuit Performance
• RF applications
• High efficiency at light load
• Output ripple voltage <100mV
L1
120µH
VIN
+2.7V to +4.2V
U1 MIC2142
C1
10µF
6.3V
VCC
R3
1M
SW
D1
MBR0520
R1
453k
FB
EN
GND
C2
1µF
VOUT
6V/6mA
C4
270pF
R2
124k
C3
10µF
6.3V
GND
GND
VIN
V
IIN
mA
VOUT
V
IOUT
mA
Eff
%
2.7V
15.3mA
6.0V
6.11mA
89
4.2V
10.0mA
6.0V
6.30mA
90
Figure 2. Typical Output Data
Figure 1. High Efficiency Circuit
Bill of Materials
Item
Part Number
Manufacturer
Description
C1,C3
GRM40X5R106K6.3
Murata1
10µF/6.3V Ceramic
2
C2
GRM235Y5V105Z25
Murata1
1µF/25V Ceramic
1
GRM40COG271K050AB
Murata1
270pF/50V Ceramic
1
C4
D1
L1
R1
R2
R3
U1
Semiconductor2
Qty
MBR0520
On
0.5A 20V Schottky Rectifier
1
CDC5D23-121K
Sumida3
120µH
1
CRCW08054533FRT1
Vishay-Dale4
453k 1% 1/10W, size 0805
1
CRCW08051243FRT1
Vishay-Dale4
124k 1% 1/10W, size 0805
1
CRCW08051004JRT1
Vishay-Dale4
1M 5% 1/10W, size 0805
1
MIC2142BM5
Micrel5
Micropower Boost Converter
1
Note 1. Murata, tel: 949-916-4000
Note 2. On Semiconductor, tel: 800-344-3860
Note 3. Sumida, tel: 510-668-0660
Note 4. Vishay-Dale, tel: 207-324-4140
Note 5. Micrel Semiconductor, tel: 408-944-0800
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
August 2002
1
Application Hint 43c
Application Hint 43c
Micrel
MICREL, INC. 1849 FORTUNE DRIVE
TEL
+ 1 (408) 944-0800
FAX
SAN JOSE, CA 95131
+ 1 (408) 944-0970
WEB
USA
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel, Inc.
© 2002 Micrel, Incorporated
Application Hint 43c
2
August 2002