®
RT9276
Synchronous Boost Converter with Voltage Detector
General Description
The RT9276 is a synchronous boost converter, which is
based on a fixed frequency Pulse-Width-Modulation
(PWM) controller using a synchronous rectifier to obtain
maximum efficiency. The converter provides a power
supply solution for products powered by a variety of
batteries such as single cell, dual cell alkaline, NiMH and
NiCd battery. At light load currents, the converter enters
power save mode to maintain a high efficiency over a wide
load current range.
The output voltage can be programmed by an external
resistor divider, or fixed at a certain voltage. Moreover, the
converter can be disabled to minimize battery drain. During
shutdown, the load is completely disconnected from the
battery. The maximum peak current in the boost switch
is limited to 2A for current limit.
For the RT9276, a low-EMI mode is implemented to reduce
ringing of the inductor phase pin when the converter enters
discontinuous conduction mode. Moreover, a voltage
detector is built-in in the chip for low battery detection.
Features
True Load Disconnection During Shutdown
Internal Synchronous Rectifier
Up to 96% Efficiency
Current Mode PWM Operation with Internal
Compensation
Low Start-Up Voltage
Low Quiescent Current
Internal Soft-Start Control
Low Battery Comparator
Low EMI Converter (Anti-Ringing)
Power Save Mode for Improved Efficiency at Light
Load Current
Over Current Protection
Short Circuit Protection
Over Temperature Protection
Over Voltage Protection
Small WDFN-10L 3x3 Package
RoHS Compliant and Halogen Free
Applications
All One-Cell, Two-Cell and Three-Cell Alkaline, NiCd,
NiMH and Single-Cell Li Batteries
Hand-Held Devices
WLED Flash Light
Ordering Information
RT9276(
-
)
Package Type
QW : WDFN-10L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Boost VOUT
Default : Adjustable
33 : 3.3V
50 : 5.0V
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)
EN
VOUT
FB/NC
LBO
GND
1
2
3
4
5
10
9
8
7
6
11
PGND
LX
PGOOD
LBI
VBAT
WDFN-10L 3x3
Marking Information
EW= : Product Code
EW=YM
DNN
YMDNN : Date Code
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9276-02 July 2013
GND
www.richtek.com
1
RT9276
Typical Application Circuit
L
V
BAT
C
IN
R1
7
R2
LBI
LBO 4
8
PGOOD
GND
5, Exposed Pad (11)
RT9276
9 LX
6 VBAT
VOUT
2
R3
FB 3
R4
LBO
PGOOD
C
OUT
R5
R6
V
OUT
10 PGND
1 EN
Chip Enable
Figure 1. Adjustable Output Voltage Boost Converter with Voltage Detector
L
V
BAT
C
IN
R1
RT9276
9 LX
6 VBAT
7
VOUT
2
R3
LBO 4
LBI
PGOOD
8
PGOOD
NC 3
GND
5, Exposed Pad (11)
C
OUT
R4
V
OUT
R2
10 PGND
1 EN
Chip Enable
Figure 2. Fixed Output Voltage Boost Converter with Voltage Detector
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
9
10
Pin Name
EN
VOUT
FB / NC
LBO
GND
VBAT
LBI
PGOOD
LX
PGND
Chip Enable (Active High).
Boost Output.
Feedback Input for Adjustable Output Voltage Version / No Internal Connection
for Fixed Output Voltage Version.
Voltage Detector Output.
Ground.
Battery Supply Input.
Voltage Detector Input.
Power Good Indicator.
Switching Node. Connect this pin to an inductor.
Power Ground.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Pin Function
11 (Exposed Pad) GND
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS9276-02 July 2013
RT9276
Function Block Diagram
PGOOD VOUT
VBAT
EN
V
REF1
Soft-Start
Control
OCP,
OTP,
OVP
EA
PWM
Logic
UGATE
Control
Determine
Higher Voltage
Back Gate
Control
LX
FB
LGATE
Current
Sense
PGND
LBO
GND
Internal
Compensation
V
REF2
+
-
LBI
Figure 3. Adjustable Voltage Regulator
PGOOD VOUT
VBAT
EN
V
REF1
VOUT
Soft-Start
Control
OCP,
OTP,
OVP
EA
Logic
UGATE
Control
Determine
Higher Voltage
Back Gate
Control
LX
PWM
Current
Sense
LGATE
PGND
LBO
GND
Internal
Compensation
V
REF2
+
-
LBI
Figure 4. Fixed Voltage Regulator
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9276-02 July 2013
www.richtek.com
3
RT9276
Absolute Maximum Ratings
(Note 1)
−0.3V
to 6V
−0.3V
to 6.5V
−0.3V
to 6.5V
−2V
to 7.5V
−0.3V
to 6V
−0.3V
to 6V
−0.3V
to 6V
Supply Input Voltage, V
BAT
----------------------------------------------------------------------------------------------
Boost Output Voltage, V
OUT
--------------------------------------------------------------------------------------------
Switch Output Voltage, LX ----------------------------------------------------------------------------------------------
<10ns ------------------------------------------------------------------------------------------------------------------------
Digital Input Voltage, EN, LBI ------------------------------------------------------------------------------------------
Digital Output Voltage, LBO, PGOOD --------------------------------------------------------------------------------
Others Pin -------------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-10L 3x3 ------------------------------------------------------------------------------------------------------------- 1.429W
Package Thermal Resistance (Note 2)
WDFN-10L 3x3,
θ
JA
------------------------------------------------------------------------------------------------------- 70°C/W
WDFN-10L 3x3,
θ
JC
------------------------------------------------------------------------------------------------------- 8.2°C/W
Junction Temperature Range -------------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- 260°C
Storage Temperature Range --------------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------------ 200V
Recommended Operating Conditions
(Note 4)
Supply
Input Voltage Range, V
BAT
------------------------------------------------------------------------------------- 1.2V to 5V
Junction Temperature Range --------------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range --------------------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
Parameter
Pre-charge Current
DC/DC Stage
Minimum Start-Up Input Voltage
(V
BAT
≥
2.5V or V
BAT
= V
OUT
+ 0.7V, V
EN
= V
BAT
, C
IN
= 10μF, C
OUT
= 22μF, T
A
= 25°C, unless otherwise specified)
Symbol
I
Pre-chg
Test Conditions
V
IN
= 5V
Min
--
Typ
100
Max
--
Unit
mA
V
BAT
I
LOAD
= 1mA
--
0.8
--
1.2
--
--
0.5
--
1.2
90
100
2
--
5
5
0.51
3
1.44
--
--
5
V
V
V
V
%
MHz
%
μA
μA
Input Voltage Range After Start-Up V
BAT
Output Voltage Range
Feedback Reference Voltage
Output Voltage Accuracy
Switching Frequency
Maximum Duty Cycle
Non-Switching Quiescent Current
Shutdown Current
V
OUT
V
FB
ΔV
OUT
f
LX
D
MAX
I
Q,NS
I
SHDN
No Switching
V
EN
= 0, V
BAT
= 1.2V
For Adjustable Output Voltage
For Fixed Output Voltage
0.49
−3
0.96
--
--
--
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS9276-02 July 2013
RT9276
Parameter
Protection
Over-Temperature Protection
Over-Temperature Hysteresis
Over-Current Protection
Over-Voltage Protection
Power MOSFET
N-MOSFET ON-Resistance
R
DS(ON)_N
V
OUT
= 3.3V
V
OUT
= 5V
V
OUT
= 3.3V
V
OUT
= 5V
Rising
Falling
--
--
--
--
220
200
260
240
--
--
--
--
mΩ
m
Ω
T
OTP
T
OTP_Hys
I
OCP
V
OVP
V
OUT
= 3.3V
--
--
1.6
5.4
170
40
2
--
--
--
2.4
6
°C
°C
A
V
Symbol
Test Conditions
Min
Typ
Max
Unit
P-MOSFET ON-Resistance
Enable Control
EN Threshold
Voltage
Voltage Detector
LBI Voltage Threshold
LBI Voltage Hysteresis
LBO Output Impedance
Logic-High
Logic-Low
R
DS(ON)_P
V
IH
0.8
--
--
--
--
0.2
V
IL
V
LBI_Rising
V
LBI_Hys
R
ON_LBO
V
0.49
--
V
LBI
= 0V, V
OUT
= 3.3V
--
0.5
10
15
0.51
--
--
V
mV
Ω
Note 1.
Stresses beyond those listed
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect
device reliability.
Note 2.
θ
JA
is measured at T
A
= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7.
θ
JC
is
measured at the exposed pad of the package.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS9276-02 July 2013
www.richtek.com
5
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