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Número de pieza | KB3302 | |
Descripción | 2MHz Step-up Switching regulator | |
Fabricantes | Kingbor Technology | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de KB3302 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
No Preview Available ! Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB3302
2Amp, 2MHz Step-up Switching
regulator with Soft-Start
FEATURES
■ Up to 95% Efficiency
■ TDB uA No Load Current
www.DataSheet4U.com
■ 1000mA Output Current
■ 1.5V to 16V Input Voltage Range
■ Programmable switching frequency up to 2MHz
■ Output voltage up to 32V
■ Constant switching frequency current-mode control
■ 1.23V Reference Allows Low Output Voltages
■ Shutdown Mode Draws ) 10 µA Supply Current
■ Low saturation voltage switch: 220mV at 2A
■ Overtemperature Protected,Soft-Start function
■ 8-Pin MSOP Packages
DESCRIPTION
The KB3302 is a high-frequency current-mode step-up
switching regulator with an integrated 2A power transis-
tor. Its high switching frequency (programmable up to
2MHz) allows the use of tiny surface-mount external pas-
sive components. Programmable soft-start eliminates high
inrush current during start-up. The internal switch is rated
at 32V making the converter suitable for high voltage ap-
plications such as Boost, SEPIC and Flyback.
The operating frequency of the KB3302 can be set with an
external resistor. The ability to set the operating frequency
gives the KB3302 design flexibilities. A dedicated COMP
pin allows optimization of the loop response. The KB3302
is available in thermally enhanced 8-Pin MSOP packages.
APPLICATIONS
■ Flat screen LCD bias supplies
■ TFT bias supplies
■ XDSL power supplies
■ Medical equipment
■ Digital video cameras
■ Portables devices
■ White LED power supplies
TYPICAL APPLICATION
VIN = 3.3V
TO 4.2V
L1
3.3µH
C1
4.7µF
6
VIN
3 SHDN KB3302
7 SS MSOP8
1N5819
5
SW
FB 2
COMP 1
100nF
GND
4
ROSC
8
R3
10.7k
R3
17.4k
1nF
R1
300k
R2
100k
VOUT
5.0V
1000mA
C3
22 µF
L1: Sumida CR43
Figure 1. 1.2MHzAll Ceramic Capacitor Single Li-ion Cell
to 5V Boost Converter.
KB3302 Efficiency
95
VOUT = 5V
90
1.2MHz
85
80
VIN = 4.2V
75
70
65
60
VIN = 3.6V
55
VIN = 2.6V
50
0.001
0.010
0.100
Load Current (A)
1.000
1
1 page Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB3302
PIN FUNCTIONS
Pin Pin Name Pin Function
1 COMP The output of the internal transconductance error amplifier. This pin is used for loop compensation.
2 FB The inverting input of the error amplifier. Tie to an external resistive divider to set the output voltage.
www.DataShee3t4U.com SHDN
4 GND
Shutdown Pin. The accurate 1.1V shutdown threshold and the 4.6uA shutdown pin current
hysteresis allow the user to set the undervoltage lockout threshold and hysteresis for the switching
regulator. Pulling this pin below 0.1V causes the converter to shut down to low quiescent current.
Tie this pin to IN if the UVLO and the shutdown features are not used. This pin should not be left
floating.
Ground. Tie to the ground plane.
5 SW Collector of the internal power transistor. Connect to the boost inductor and the rectifying diode.
6 IN Power Supply Pin. Bypassed with capacitors close to the pin.
7
ROSC
A resistor from this pin to the ground sets the switching frequency.
8
SS
Soft-Start Pin. A capacitor from this pin to the ground lengthens the start-up time and reduces start-
up current.
Exposed Pad The exposed pad must be soldered to the ground plane on the PCB for good thermal conduction.
SIMPLIFIED BLOC DIAGRAM
IN
6
4.6µA
SHDN
3
1.1V
+
CMP
-
VOLTAGE
REFERENCE
THERMAL
SHUTDOW N
INTERNAL
SUPPL Y
ENABLE
CLK
REG
FB
2
COMP
1
SS
8
1.242V
REG_GOOD
ENABL E
+
EA
-
ROS C
7
REG
1.5µA
CLK
-
PWM
+
R
Q
S
+
ILIM
-
I-LIMIT
+
Σ
+
OSCILLATOR
SLOP E COMP
+
ISEN
-
SW
5
RSENSE
4
GND
5
5 Page Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB3302
APPLICATIONS INFORMATION
The turn off voltage is:
www.DataSheet4U.com R3
R4
IN
6/8
SHDN
3
I HYS
4.6µA
SWITCH CLOSED
WHEN Y = “1”
+
1.1V
-
COMPARATOR
Y
KB3302
VL = VH − VHYS = 2.75 − 0.69 = 2.06V > 1.4V .
Frequency Compensation
Figure 8 shows the equivalent circuit of a boost converter
using the KB3302. The output filter capacitor and the load
form an output pole at frequency:
ωp2
= − 2IOUT
VOUTC2
=
−2
ROUTC2
(13)
where
C
2
is
the
output
capacitor
and
ROUT
=
VOUT
IOUT
is
the
equivalent load resistance.
Figure 7. Programmable Hysteretic UVLO Circuit
The zero formed by C and its equivalent series resistance
2
(ESR) is neglected due to low ESR of the ceramic output
capacitor.
with VL > 1.4V .
Example: Increase the turn on voltage of a V = 3.3V boost
IN
converter from 1.4V to 2.75V.
Using
V
H
=
2.75V
and
R
4
=
100KΩ
in
(12),
R3 = 150KΩ .
The resulting UVLO hysteresis is:
There is also a right half plane (RHP) zero at angular
frequency:
ωZ2
=
ROUT (1
L
− D)2
(14)
ωz2 decreases with increasing duty cycle D and increasing
I . Using the 5V to 12V boost regulator (1.35MHz) in
OUT
Figure 1(a) as an example,
VHYS = IHYSR3 = 4.6µA •150KΩ = 0.69V .
ROUT
≥
5V
0.74A
=
6.8Ω
VIN POWER
STAGE
COMP
-
Gm
+
R3
C6 RO
FB
1.242V
C4 VOLTAGE
REFERE N CE
C5 R1
IOUT
VOUT
ESR
C2
ROUT
R2
Figure 8. Simplified Block Diagram of a Boost Converter
11
11 Page |
Páginas | Total 17 Páginas | |
PDF Descargar | [ Datasheet KB3302.PDF ] |
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