KB3301 View Datasheet(PDF) - Kingbor Technology Co
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KB3301 Datasheet PDF : 5 Pages
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KB3301
Applications
Application Note
䃂 High Current Application
L1
Vin
3.3--10uH
D1
+ C5
100uF
1N5819
Vout
3.3V/5V
䃂 Output Voltage Setting
Referring to application circuits, the output voltage of the
switching regulator (VOUT) can be set
R1
VOUT1 = (1 + R2 ) × 1.25V
䊶䊶䊶㪘
C2
1uF
VDD EXT
CE KB3301 LX
GND FB
R1
1.6M/100K
Q1
NMOS
+
C1
100uF
R2
980k/33K
ƽ High Voltage Application
Vin=3.1VД6.5V Vout=12V
NMOS= XP161A1355PR FDN337N
Vin=2.8V~ 6.5V Vout=9V
Vin=4.0VД6.5V Vout=8V
L1
4.7uH 2.5A D1
C1=47uF
C2=10uF
C3=NC
+
C4
47uF
RVDD
47
CVDD
1N5819
R1=860K/620K/210K
R2=100K/100K/39K
RM=0.2
CVDD=1uF
VDD EXT
Q1
NMOS
12V / 9V / 8V
1000mA
CE KB3301 LX
GND FB
C3
R1
˥ˠ R2 C2
+
C1
䃂 Feedback Loop Design
Referring to application circuits, The selection of R1and
R2 based on the trade-off between quiescent current
consumption and interference immunity is stated below:
ƹ Follow Equation A
ƹ Higher R reduces the quiescent current (Path current
=1.25V/R2), however resistors beyond 5MΩ are not
recommended.
ƹ Lower R gives better noise immunity, and is less
sensitive to interference, layout parasitics, FB node
leakage, and improper probing to FB pins.
ƹ A proper value of feed forward capacitor parallel with
R1 can improve the noise immunity of the feedback
loops, especially in an improper layout. An empirical
suggestion is around 0~33pF for feedback resistors
of MΩ, and 10nF~0.1µF for feedback resistors of tens
to hundreds KΩ.
ƽ Multi-Output Applications
Vin
3.3V/5V
L1
3.3--10uH
D1 1N5819
R3
100
C1
1uF
C2
10uF
Q1
NMOS
VDD
EXT
CE KB3301 LX
GND FB
C8
1uF
C7
1uF
C6
R1
R2
R1=620K
R2=100
C6=0.1uF
Vout2
+18V 10mA
C3
10uF Vout1
+9V 100mA
C4
10uF Vout3
-9V 10mA
C5
10uF
For applications without standby or suspend modes,
lower values of R1 and R2 are preferred. For applications
concerning the current consumption in standby or
suspend modes, the higher values of R1and R2 are
feedback needed. Such "high impedance loops" are
sensitive to any interference, which require careful
layout and avoid any interference, e.g. probing to FB pin.
P4 / 5
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