mic4690 Micrel Semiconductor, mic4690 Datasheet - Page 8

• Manufacturer Part Number: mic4690
• Description: Mic4690 500khz 1a Superswitcher? Buck Regulator
• Manufacturer: Micrel Semiconductor

MIC4690
Applications Information
Adjustable Regulators
Adjustable regulators require a 1.23V feedback signal. Rec-
ommended voltage-divider resistor values for common out-
put voltages are included in Figure 1b.
For other voltages, the resistor values can be determined
using the following formulas:
Bill of Material Matrix
Note 1.
MIC4690
V
5.0V
5.0V
3.3V
2.5V
1.8V
OUT
R1 R2
V
V
OUT
REF
All resistors 1%
R1
3.01k
3.01k
3.01k
3.01k
3.01k
=
(1)
=
=
1.23V
⎛
⎜
⎝
V
REF
V
V
OUT
REF
R2
976Ω
976Ω
1.78k
6.49k
2.94k
⎛
⎜
⎝
(1)
R2
R1
−
1
⎞
⎟
⎠
+
V
6.8V-30V
6.8V-14V
4.9V-14V
4.25V-14V 47µF, 20V
4.0V-14V
1
⎞
⎟
⎠
IN
Figure 1b. Recommended Components for Common Ouput Voltages
C
22µF, 35V
Vishay-Dale
595D226X0035D2T
Micro Commercial
47µF, 20V
Vishay-Dale
595D476X0020C2T
Micro Commercial
47µF, 20V
Vishay-Dale
595D476X0020C2T
Micro Commercial
Vishay-Dale
595D476X0020C2T
Micro Commercial
47µF, 20V
Vishay-Dale
595D476X0020C2T
Micro Commercial
IN
D1
2A, 40V
Schotty
SS24
2A, 20V
Schotty
SS22
2A, 20V
Schotty
SS22
2A, 20V
Schotty
SS22
2A, 20V
Schotty
SS22
8
HUTDOWN
ENABLE
L1
18µH
Sumida
CDRH6D38-180ML
18µH
Sumida
CDRH6D38-180ML
15µH
Sumida
CDRH6D38-150ML
10µH
Sumida
CDRH6D38-100ML
10µH
Sumida
CDRH6D38-100ML
+6.8V to +30V
Figure 1a. Adjustable Regulator Circuit
Power
OP-8
22
35V
C1
µ
F
2
1
VIN
HDN
IC4690B
GND
5Ð8
C
220µF, 10V
Vishay-Dale
594D227X0010D2T
100µF, 6.3V
Vishay-Dale
595D107X06R3C2T
120µF, 4.0V
Vishay-Dale
595D127X0004C2T
120µF, 4.0V
Vishay-Dale
595D127X0004C2T
120µF, 4.0V
Vishay-Dale
595D127X0004C2T
OUT
FB
W
3
4
D1
2A
40V
18
L1
µ
H
R1
3.01k
R2
1.27k
I
see SOA
1.0A
1.0A
1.0A
1.0A
April 2005
OUT
Micrel
5.0V/1A
C2
220
10V
µ
F