Synchronous Boost DC/DC Regulator

Preliminary Datasheet
LP6206
Synchronous Boost DC/DC Regulator
General Description
Features
The LP6206 is high efficiency synchronous, fixed
frequency, current-mode step-up converter with
output to input disconnect. A PWM step-up DC/DC
converters optimized to provide a high efficiency
solution to medium power system. When LP6206
is disabled, the internal conduction path from the
battery. This output disconnect feature reduces the
shutdown current to typically only 50nA. the
devices regulates the output voltage up to 6V from
either a 2cell NiMH/NiCd or a single-cell Li-ion
Battery with a 500KHz fixed frequency switching.
These features minimize overall solution footprint
by allowing the use of tiny, low profile inductors
and ceramic capacitors.
Ordering Information
LP6206 -
□ □
Up to 94% efficiency
Output to Input Disconnect at Shutdown Mode
Shut-down current:<1uA 
Output voltage Up to 5V
Internal Synchronous Rectifier
Internal Soft-start
Internal Compensation
500KHz fixed frequency switching
High switch on current:1.6A
50nA Shutdown Current
Available in SCT23-5 Package 
Applications
Battery products
Host Products
□
F: Pb-Free
Pin Configurations
Package Type
B5: TSOT23-5
Typical Application Circuit
Vin
4.7uH
+
Vout
SW
4
22uF
OUT
3
+
EN
LP6206
FB
1
2
GND
5
22pF
R1
1.5M
Cout
22uF
R2
500K
Marking Information
Please see website.
LP6206 –00
Ver. 1.0 Datasheet
Dec.-2008
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Page 1 of 7
Preliminary Datasheet
Functional Pin Description
LP6206
PIN
PIN Name
Description
1
FB
2
3
4
GND
OUT
SW
5
EN
Regulation Feedback Input. Connect to an external resistive voltage
divider from the output to FB to set the output voltage.
Ground.
Supply Input for the LP6206. Connect to the output of the converter.
Output switching node. SW is the drain of the internal low-side
N-Channel MOSFET and high-side P-Channel MOSFET. Connect the
inductor to SW to Complete the step-up converter.
Regulator On/off Control Input. A logic high input(VEN>1.4V) turns on
the regulator. A logic low input(VEN<0.4V) puts the LP6206 into low
current shutdown mode.
Function Block Diagram
LP6206 –00
Ver. 1.0 Datasheet
Dec.-2008
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Page 2 of 7
Preliminary Datasheet
LP6206
Absolute Maximum Ratings
Supply Input Voltage---------------------------------------------------------------------------------------------------------------6V
Power Dissipation, PD @ TA = 25°C
SOT23-5--------------------------------------------------------------------------------------------------------600mW
Package Thermal Resistance
SOT23-5, θJA ---------------------------------------------------------------------------------------------------------------250°C/W
Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------------260°C
Storage Temperature Range --------------------------------------------------------------------------------- −65°C to 150°C
Recommended Operating Conditions
Supply Input Voltage-------------------------------------------------------------------------------------------------2.2V to 6V
EN Input Voltage -------------------------------------------------------------------------------------------------------0V to 5.5V
Operation Junction Temperature Range ------------------------------------------------------------------−40°C to 125°C
Operation Ambient TemperatureRange----------------------------------------------------------------------−40°C to 85°C
Electrical Characteristics
(Vin=2.4V,Vout=3.5V,Cin=10uF,Cout=10uF,L1=4.7uH,R1=178K,R2=100K,Ta=-40 ℃
noted.Typical values are at TA=25℃.)
Parameter
Conditions
to 85 ℃ ,unless otherwise
Supply Voltage
LP6206
Min
Typ Max
2.2
5
Output Voltage Range
2.5
Supply Current(Shutdown)
VEN=VOUT=0V,VSW=5V
0.05
Supply Current
VFB=1.3V
0.39
Feedback Voltage
Feedback Input Current
1.2
VFB=1.2V
1.25
Units
V
6
V
1
uA
mA
1.3
50
V
nA
Switching Frequency
310
500
690
KHz
Maximum Duty Cycle
80
85
90
%
0.4
V
EN Input Low Voltage
EN Input High Voltage
1.4
EN Pull Down Resistance
Low-side On Resistance
1
Vout=3.3V
450
Low-side Current Limit
High-side On Resistance
LP6206 –00
Ver. 1.0 Datasheet
V
1.4
Vout=3.3V
Dec.-2008
1.6
2
650
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Page 3 of 7
A
Preliminary Datasheet
LP6206
Typical Operating Characteristics
LP6206 –00
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Dec.-2008
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Page 4 of 7
Preliminary Datasheet
LP6206 –00
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LP6206
Page 5 of 7
Preliminary Datasheet
LP6206
Operation Information
Application Information
Component selection
Setting the Output Voltage
Set the output voltage by selecting the resistive
voltage divider ratio. The voltage divider drops the
output voltage to the 1.25V feedback voltage. Use a
100K resistor for R2 of the voltage divider.
Determine the high-side resistor R1 by the equation:
Vout=(R1/R2+1) X VFB
5V Typical Application with External Diode(A)
Vin
4.7uH
+
Vout
SW
4
22uF
OUT
3
+
5
LP6206
GND
EN
FB
22pF
1
R1
1.5M
5V Typical Application with External Diode(B)
Vin
4.7uH
LP6206 –00
Ver. 1.0 Datasheet
Dec.-2008
+
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PMOS
4
22uF
SW
EN
--
FB
0.22uF
Vout
3
+
LP6206
GND
5
OUT
2
Soft-Start
The LP6206 includes a soft-start timer that limits
the voltage at the error amplifier output during
startup to prevent excessive current at the input.This
prevents premature termination of the source
voltage at start-up due to inrush current.This also
Limits thd inductor current at startup,forcing the
input current to rise slowly to the amount required
to regulate the output voltage during soft-start.
Cout
22uF
R2
500K
2
The LP6206 uses a 500KHz fixed-frequency,
current-mode regulation architecture to regulate the
output voltage. The LP6206 measures the output
voltage through an external resistive voltage divider
and compares that to the internal 1.25V reference to
generate the error voltage to the inductor current to
regulate the output voltage.the use of current-mode
regulation improves transient response and control
loop
stability.
When the LP6206 is disable(EN=Low),both power
switches are off. There is no current path from SW
to OUT. There fore, the output voltage discharges to
ground. When the LP6206 is enabled(EN=High),a
limited start-current charges the output voltage
rising to SW, then th part operates in force PWM
mode for regulating the output voltage to the target
value. At the beginning of each cycle, the N-channel
MOSFET switch is turned on, forcing the inductor
current to rise, The current at the source of the
switch is internally measured and converted to a
voltage by the current sense amplifier. That voltage
is compared to the error voltage. When the inductor
current rises sufficiently, the PWM comparator
turns off the switch, forcing the inductor current to
the output capacitor through the internal P-Channel
MOSFET rectifier, which forces the inductor
current to decrease. The peak inductor current is
controlled by the error voltage. Thus the output
voltage controls the inductor current to satisfy the
lode.
1
22pF
R1
1.5M
R2
500K
Page 6 of 7
Cout
22uF
Preliminary Datasheet
LP6206
Packaging Information
LP6206 –00
Ver. 1.0 Datasheet
Dec.-2008
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Page 7 of 7