MIC4690 Datasheet, PDF (10/12 Pages) Micrel Semiconductor – 500kHz 1A SuperSwitcher Buck Regulator

MIC4690
To minimize stray inductance and ground loops, keep trace
lengths, indicated by the heavy lines in Figure 5, as short as
possible. For example, keep D1 close to pin 3 and pins 5
through 8, keep L1 away from sensitive node FB, and keep
C_IN close to pin 2 and pins 5 though 8. See “Applications
Information: Thermal Considerations” for ground plane lay-
out.
Micrel
The feedback pin should be kept as far way from the switching
elements (usually L1 and D1) as possible.
A circuit with sample layouts are provided. See Figures 6a
though 6e. Gerber files are available upon request.
V_IN
+4V to +30V
(34V transients)
C_IN
Power
SOP-8
MIC4690BM
2
VIN
3
SW
1
SHDN
4
FB
GND
5678
L1
D1
V_OUT
C_OUT
R1
R2
GND
Figure 5. Critical Traces for Layout
J1
V_IN
4V to +30V
(34V transients)
C1
22µF
35V
J3
GND
OFF
C2
0.1µF
50V
ON
JP1
U1 MIC4690BM
2
IN
3
SW
1
SHDN
4
FB
SOP-8
GND
5Ð8
* C3 can be used to provide additional stability
and improved transient response.
L1
18µH
R1
3.01k
C3* 1800pF / 50V
optional
D1
2A
40V
R6
optional
1
2
R2
6.49k
3
JP2a
1.8V
4
R3
2.94k
5
JP2b
2.5V
6
R4
1.78k
7
JP2c
3.3V
8
R5
976½
JP2d
5.0V
Figure 6a. Evaluation Board Schematic Diagram
C4
220µF
10V
J2
V_OUT
1A
C5
0.1µF
50V
J4
GND
MIC4690
10
June 2001