RT9266B
Tiny Package, High Efficiency, Step-Up DC/DC Converter
General Description
The RT9266B is a compact, high efficiency, and low
voltage step-up DC/DC converter with an Adaptive
Current Mode PWM control loop, includes an error
amplifier, ramp generator, comparator, switch pass
element and driver in which providing a stable and high
efficient operation over a wide range of load currents. It
operates in stable waveforms without external
compensation.
The low start-up input voltage below 1V makes RT9266B
suitable for 1 to 4 battery cells applications with a 500mA
internal switch. The 550kHz high switching rate minimized
the size of external components. Besides, the 25μA low
quiescent current together with high efficiency maintains
long battery lifetime.
Features
1V Low Start-up Input Voltage at 1mA Load
25μA Quiescent (Switch-off) Supply Current
μ
Zero Shutdown Mode Supply Current
90% Efficiency
550kHz Switching Frequency at 3.3V V
DD
Providing Flexibility for Using Internal and External
Power Switches
Small
SOT-23-6
Package
RoHS Compliant and 100% Lead (Pb)-Free
Applications
PDA
DSC
LCD Panel
RF-Tags
MP3
Portable Instrument
Wireless Equipment
Ordering Information
RT9266B
Package Type
E : SOT-23-6
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Pin Configurations
(TOP VIEW)
FB VDD LX
6
5
4
2
3
EN EXT GND
SOT-23-6
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
DS9266B-11 April 2011
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1
RT9266B
Typical Application Circuit
L1
V
IN
C3
10uF
3.3 to 10 uH
D1
SS0520
V
OUT
3.3V/5V
R1
1.6M/3M
LX
FB
R2
980k/1M
C1
10uF
C2
1uF
VDD
EN
EXT
RT9266B
GND
Figure 1. RT9266B Typical Application for Portable Instruments
L1
V
IN
C3
10uF
3.3 to 10 uH
D1
SS0520
V
OUT
3.3V/5V
C2
1uF
VDD
EN
LX
Q1
N MOS
R1
1.6M/3M
C1
10uF
R2
980k/1M
RT9266B
EXT
GND
FB
Figure 2. RT9266B for Higher Current Applications
Test Circuit
I (V
IN
)
V
IN
L1
C3
10uF
10uH
+
D1
SS0520
V
OUT
3.3V/5V
R1
1.6M/3M
C4
100p
C5
10uF
A
A
I (V
DD
)
VDD
EN
EXT
RT9266B
GND
LX
FB
C2
1uF
R2
980k/1M
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DS9266B-11 April 2011
RT9266B
Functional Pin Description
Pin Name Pin Function
EN
EXT
GND
LX
VDD
FB
Chip Enable (Active High)
Output Pin for Driving External NMOS
Ground
Pin for Switching
Input Positive Power Pin of RT9266B
Feedback Input Pin
Internal Reference Voltage for the Error Amplifier is 1.25V.
Function Block Diagram
EXT
VDD
RT9266B
LX1
FB
1.25V
VDD
R2
Shut Down
EN
Q3
N MOS
Over Temp.
Detector
-
+
Loop Control Circuit
Q1
N MOS
R1
GND
DS9266B-11 April 2011
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3
RT9266B
Absolute Maximum Ratings
Supply Voltage ---------------------------------------------------------------------------------------------------
−
0.3V to 7V
LX Pin Switch Voltage ------------------------------------------------------------------------------------------
−
0.3V to 6.5V
Other I/O Pin Voltages ------------------------------------------------------------------------------------------
−
0.3V to (V
DD
+ 0.3V)
LX Pin Switch Current ------------------------------------------------------------------------------------------ 2.5A
EXT Pin Driver Current ------------------------------------------------------------------------------------------ 200mA
Package Thermal Resistance
SOT-23-6,
θ
JC
----------------------------------------------------------------------------------------------------- 145°C/W
Operating Junction Temperature ------------------------------------------------------------------------------ 125°C
Storage Temperature Range -----------------------------------------------------------------------------------
−
65°C to +150°C
Electrical Characteristics
(V
IN
= 1.5V, V
DD
set to 3.3V, Load Current = 0, T
A
= 25°C, unless otherwise specified)
Parameter
Start-UP Voltage
Operating VDD Range
No Load Current I (V
IN
)
Switch-off Current I (V
DD
)
Shutdown Current I (V
IN
)
Feedback Reference Voltage
Switching Frequency
Maximum Duty
LX ON Resistance
Current Limit Setting
Current Limit Delay Time
EXT ON Resistance to V
DD
EXT ON Resistance to GND
Line Regulation (refer to V
FB
)
Load Regulation (refer to V
FB
)
EN Pin Trip Level
Temperature Stability for Vout
Thermal Shutdown
Thermal Shutdown Hysteresis
T
S
Symbol
V
ST
V
DD
I
NO LOAD
I
SWITCH OFF
I
OFF
V
REF
F
S
D
MAX
Test Conditions
I
L
= 1mA
VDD pin voltage
V
IN
= 1.5V, V
OUT
= 3.3V
V
IN
= 6V
EN Pin = 0V, V
IN
= 4.5V
Close Loop, V
DD
= 3.3V
V
DD
= 3.3V
V
DD
= 3.3V
V
DD
= 3.3V
Min
--
2
--
--
--
1.225
--
--
--
--
--
--
--
--
--
0.4
--
--
--
Typ
0.98
--
150
25
0.01
1.25
550
95
0.35
0.5
300
5
5
12
0.25
0.8
50
165
10
Max
1.05
6.5
--
--
1
1.275
--
--
--
--
--
--
--
--
--
1.2
--
--
--
Unit
V
V
μA
μA
μA
V
kHz
%
Ω
A
ns
Ω
Ω
mV/V
mV/mA
V
ppm/
°C
°C
°C
I
LIMIT
V
DD
= 3.3V
V
DD
= 3.3V
V
DD
= 3.3V
V
DD
= 3.3V
ΔV
LINE
ΔV
LOAD
V
IN
= 1.5 ~ 2.5V, I
L
= 50mA
V
IN
= 2.5V, I
L
= 1 ~ 100mA
V
DD
= 3.3V
T
SD
ΔT
SD
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DS9266B-11 April 2011
RT9266B
Typical Operating Characteristics
Efficiency vs. Output Current
95
90
85
Efficiency vs. Output Current
100
Efficiency (%)
80
75
70
65
V
IN
= 1V
Efficiency (%)
V
IN
= 3V
V
IN
= 2.5V
V
IN
= 2V
V
IN
= 1.5V
90
80
V
IN
= 4.5V
V
IN
= 4V
V
IN
= 3.5V
V
IN
= 3V
V
IN
= 2.5V
V
IN
= 2V
V
IN
= 1.5V
70
V
OUT
= 3.3V, T
A
= 25°C
60
1
10
100
1000
V
OUT
= 5V, T
A
= 25°C
60
1
10
100
1000
Output Current (mA)
Output Current ( mA)
Output Voltage vs. Output Current
3.36
Output Voltage vs. Output Current
5.1
Output Voltage (V)
V
IN
= 3V
Output Voltage (V)
3.32
5.05
V
IN
= 4.5V
5
V
IN
= 4V
V
IN
= 3.5V
3.28
V
IN
= 2.5V
4.95
V
IN
= 2V
3.24
V
IN
= 3V
V
IN
= 1.5V
4.9
V
IN
= 1.5V
V
IN
= 1V
V
OUT
= 3.3V, T
A
= 25°C
V
IN
= 2.5V
V
IN
= 2V
V
OUT
= 5V, T
A
= 25°C
4.85
100
1000
3.2
1
10
1
10
100
1000
Output Current (mA)
Output Current (mA)
Input Current vs. Input Voltage
350
300
800
700
Input Current vs. Input Voltage
Input Current (uA)
250
200
150
100
50
Input Current (uA)
V
OUT
= 3.3V @ no load
600
500
400
300
200
100
V
OUT
= 5V @ no load
0
0
1
1.5
2
2.5
3
1
2
3
4
5
Input Voltage (V)
DS9266B-11 April 2011
Input Voltage (V)
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