®
RT9276
Synchronous Boost Converter with Voltage Detector
General Description
Features
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.
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True Load Disconnection During Shutdown
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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
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.
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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.
Ordering Information
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Applications
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All One-Cell, Two-Cell and Three-Cell Alkaline, NiCd,
NiMH and Single-Cell Li Batteries
Hand-Held Devices
WLED Flash Light
Package Type
QW : WDFN-10L 3x3 (W-Type)
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Lead Plating System
G : Green (Halogen Free and Pb Free)
Pin Configurations
(TOP VIEW)
Boost VOUT
Default : Adjustable
33 : 3.3V
50 : 5.0V
EN
VOUT
FB/NC
LBO
GND
1
2
3
4
5
GND
RT9276(-
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11
10
9
8
7
6
PGND
LX
PGOOD
LBI
VBAT
Note :
WDFN-10L 3x3
Richtek products are :
`
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
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Marking Information
EW= : Product Code
Suitable for use in SnPb or Pb-free soldering processes.
EW=YM
DNN
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS9276-02 July 2013
YMDNN : Date Code
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
RT9276
Typical Application Circuit
L
VBAT
CIN
RT9276
2
9 LX
VOUT
6 VBAT
VOUT
R3
COUT
FB 3
R1
7
R2
10 PGND
Chip Enable
R5
R6
R4
LBI
LBO 4
8
PGOOD
1 EN
GND
LBO
PGOOD
5, Exposed Pad (11)
Figure 1. Adjustable Output Voltage Boost Converter with Voltage Detector
L
VBAT
CIN
RT9276
2
9 LX
VOUT
6 VBAT
7
Chip Enable
R3
COUT
LBO 4
R1
R2
VOUT
R4
LBI
10 PGND
PGOOD
1 EN
8
PGOOD
NC 3
GND
5, Exposed Pad (11)
Figure 2. Fixed Output Voltage Boost Converter with Voltage Detector
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
EN
Chip Enable (Active High).
2
VOUT
Boost Output.
3
FB / NC
Feedback Input for Adjustable Output Voltage Version / No Internal Connection
for Fixed Output Voltage Version.
4
LBO
Voltage Detector Output.
5
GND
Ground.
6
VBAT
Battery Supply Input.
7
LBI
Voltage Detector Input.
8
PGOOD
Power Good Indicator.
9
LX
Switching Node. Connect this pin to an inductor.
10
PGND
Power Ground.
11 (Exposed Pad) GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS9276-02 July 2013
RT9276
Function Block Diagram
PGOOD VOUT
Determine
Higher Voltage
Soft-Start
Control
EN
OCP,
OTP,
OVP
VREF1
EA
FB
VBAT
Logic
UGATE
Control
Back Gate
Control
LX
PWM
LGATE
Current
Sense
GND
Internal
Compensation
PGND
LBO
VREF2
+
-
LBI
Figure 3. Adjustable Voltage Regulator
PGOOD VOUT
Determine
Higher Voltage
Soft-Start
Control
EN
VREF1
OCP,
OTP,
OVP
VOUT
VBAT
Logic
UGATE
Control
Back Gate
Control
LX
EA
LGATE
PWM
Current
Sense
PGND
GND
LBO
Internal
Compensation
VREF2
+
-
LBI
Figure 4. Fixed Voltage Regulator
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS9276-02 July 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3
RT9276
Absolute Maximum Ratings
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(Note 1)
Supply Input Voltage, VBAT ---------------------------------------------------------------------------------------------Boost Output Voltage, VOUT -------------------------------------------------------------------------------------------Switch Output Voltage, LX ---------------------------------------------------------------------------------------------
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