RICHTEK RT9263

RT9263
Preliminary
High Efficiency, Low Supply Current, Step-Up DC/DC Converter
General Description
Features
The RT9263 is a compact, high efficient, step-up DC/DC
converter with an adaptive current mode PWM control
loop, providing a stable and high efficient operation over
a wide range of load currents. It operates in both
continuous and discontinuous current modes in stable
waveforms without external compensation.
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The low start-up input voltage below 1V makes RT9263
suitable for 1 to 4 battery cell applications providing up to
400mA output current. The 550kHz high switching rate
minimized the size of external components. Besides, the
17μA low quiescent current together with high efficiency
maintains long battery lifetime.
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Applications
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Ordering Information
1.0V Low Start-up Input Voltage
High Supply Capability to Deliver 3.3V 100mA with
1V Input Voltage
17μ
μA Quiescent (Switch-off) Supply Current
90% Efficiency
550kHz Fixed Switching Rate
Providing Flexibility for Using Internal and
External Power Switches
SOT-89-5 Package
RoHS Compliant and 100% Lead (Pb)-Free
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PDA
Portable Instrument
DSC
RT9263
Package Type
X5 : SOT-89-5
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commercial Standard)
C : Chip enable control
E : Driver for external power devices
Note :
Pin Configurations
(TOP VIEW)
EN
1
VDD
2
FB
3
RichTek Pb-free and Green products are :
`RoHS compliant and compatible with the current require-
5
GND
4
LX
RT9263CCX5
SOT-89-5
ments of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes.
`100%matte tin (Sn) plating.
Marking Information
For marking information, contact our sales representative
directly or through a RichTek distributor located in your
area, otherwise visit our website for detail.
EXT
1
VDD
2
FB
3
5
GND
4
LX
RT9263ECX5
SOT-89-5
DS9263-09 March 2007
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RT9263
Preliminary
Typical Application Circuit
C3
100uF
VIN
C4
100pF
VDD
EN
R1
1.6M
L1
4.7uF
RT9263CCX5 EXT
D1
3.3V
VOUT
LX
FB
+
GND
1N5819
R2
C2
980K 1uF
C1
100uF
Figure 1. RT9263CCX5 Typical Application for Portable Instruments below 400mA
VIN
C4
100pF
VDD
L1
4.7uF
1N5819
R1
1.6M
LX
RT9263ECX5
3.3V
VOUT1
Q1
D1
N MOS
EXT
FB
+
GND
C3
100uF
R2
980K
C2
1uF
C1
100uF
Figure 2. 0.4A to 1A Output Current Application
5V
VIN
L1
C4
100uF
D1
10uF
VDD
RT9263ECX5 EXT
LX
C3
0.1uF
FB
15V
VOUT1
R1
2.2M
+
GND
Q1
N MOS
Rm
0.05 ~ 0.1
C2
R2
200K 1uF
C1
100uF
Figure 3. High Voltage Application (Rm should be added when IL > 100mA)
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DS9263-09 March 2007
RT9263
Preliminary
5V
VIN
L1
D1
10uF
C4
100uF
Q1
N MOS
15V
VOUT1
VDD
RT9263ECX5
EN
FB
R1
2.2M
+
Chip Enable
C3
0.1uF
LX
GND
C2
R2
200K 1uF
C1
100uF
Figure 4. High Voltage Application with Shutdown Control
Function Block Diagram
RT9263CCX5
LX
VDD
-
FB
EN
1.25V
+
Loop Control Circuit
Q1
N MOS
R1
GND
RT9263ECX5
VDD
EXT
LX
-
FB
1.25V
+
Loop Control Circuit
Q1
N MOS
R1
GND
DS9263-09 March 2007
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RT9263
Preliminary
Functional Pin Description
Pin No.
Pin Name Pin Function
RT9263CCX5 RT9263ECX5
Output Pin for Driving External NMOS or NPN
--
1
EXT
1
--
EN
Chip Enable Pin (Active High)
2
2
VDD
Input Positive Power Pin of RT9263
3
3
FB
4
4
LX
Pin for Switching
5
5
GND
Ground
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When driving an NPN, a resistor should be added for limiting base
Feedback Input Pin
Internal reference voltage for the error amplifier is 1.25V.
DS9263-09 March 2007
RT9263
Preliminary
Absolute Maximum Ratings
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Supply Voltage ----------------------------------------------------------------------------------------------------- −0.3V to 7V
LX Pin Switch Voltage -------------------------------------------------------------------------------------------- −0.3V to (VDD + 0.8V)
Other I/O Pin Voltages ------------------------------------------------------------------------------------------- −0.3V to (VDD + 0.3V)
LX Pin Switch Current -------------------------------------------------------------------------------------------- 2.5A
EXT Pin Driver Current -------------------------------------------------------------------------------------------- 30mA
Power Dissipation, PD @ TA = 25°C
SOT89-5 ------------------------------------------------------------------------------------------------------------- 0.5W
Package Thermal Resistance
SOT89-5, θJA ---------------------------------------------------------------------------------------------------------------------------------------------------- 300°C/W
Operating Junction Temperature ------------------------------------------------------------------------------- 150°C
Storage Temperature Range ------------------------------------------------------------------------------------ −65°C to +150°C
Electrical Characteristics
(VIN = 1.5V, VDD set to 3.3V, Load Current = 0, TA = 25°C, unless otherwise specified)
Parameter
Start-UP Voltage
Symbol
VST
Test Conditions
IL = 1mA
Min
Typ
Max
Units
--
0.98
1.05
V
*
V
Operating VDD Range
VDD
Start-up to IDD1 > 250μA
0.8
--
6.5
No Load Current I (VIN)
INO LOAD
VIN = 1.5V, VOUT = 3.3V
--
47
--
μA
Switch-off Current I (VDD)
ISWITCH OFF VIN = 6V
--
17
--
μA
Shutdown Current I (VIN)
IOFF
EN Pin = 0V, VIN = 4.5V
--
0.1
1
μA
Feedback Reference Voltage
VREF
Close Loop, VDD = 3.3V
1.225
1.25
1.275
V
Switching Rate
FS
VDD = 3.3V
--
550
--
kHz
Maximum Duty
DMAX
VDD = 3.3V
--
92
--
%
VDD = 3.3V
--
0.25
--
Ω
VDD = 3.3V
--
2
--
A
EXT ON Resistance to VDD
VDD = 3.3V
--
40
--
Ω
EXT ON Resistance to GND
VDD = 3.3V
--
30
--
Ω
LX ON Resistance
Current Limit Setting
ILIM
Line Regulation
ΔVLINE
VIN = 1.5 ~ 2.5V, IL = 1mA
--
10
--
mV/V
Load Regulation
ΔVLOAD
VIN = 2.5V, IL = 1 ~ 100mA
--
0.25
--
mV/mA
0.2
0.8
1.4
V
Guaranteed by Design
--
50
--
ppm/°C
EN Pin Trip Level
VDD = 3.3V
Temperature Stability for FB, LFB, LBI TS
Thermal Shutdown
TSD
Guaranteed by Design
--
165
--
°C
Thermal Shutdown Hysterises
ΔTSD
Guaranteed by Design
--
10
--
°C
* Note: The EN pin shall be tied to VDD pin and inhibit to act the ON/OFF state whenever the VDD pin voltage may reach to 5.5V
or above.
DS9263-09 March 2007
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5
RT9263
Preliminary
Typical Operating Characteristics
Efficiency for 3.3V Output
Efficiency for 5.0V Output
100
100
TA = 25°C
90
80
80
70
Efficiency (%)
Efficiency (%)
TA = 25°C
90
VIN = 3.0V
2.5V
2.0V
1.5V
1.2V
1.0V
60
50
40
30
0.1
1
10
VIN = 4.0V
3.0V
2.0V
1.5V
1.2V
1.0V
60
50
40
30
Refer to Application Circuit Figure 1
20
0.01
70
100
Refer to Application Circuit Figure 1
20
0.01
0.1
1
10
1000
100
1000
I LOAD (mA)
I LOAD (mA)
No Load Current
No Load Current
140
90
TA = 25°C
VOUT = 3.3V
80
TA = 25°C
VOUT = 5.0V
120
70
100
I DD (uA)
I DD (uA)
60
50
40
80
60
30
40
20
20
10
Refer to Application Circuit Figure 1
Refer to Application Circuit Figure 1
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0
1
1.2
1.5
2
2.5
1
3
1.2
1.5
2
2.5
3
4
Input Voltage (V)
Input Voltage (V)
Start Up Voltage
Start Up Voltage
1.25
1.4
TA = 25°C
VOUT = 3.3V
1.3
TA = 25°C
VOUT = 5.0V
1.20
Input Voltage (V)
Input Voltage (V)
1.15
1.2
1.1
1.0
1.10
1.05
1.00
0.95
0.90
0.9
0.85
Refer to Application Circuit Figure 1
Refer to Application Circuit Figure 1
0.80
0.8
0
20
40
60
I LOAD (mA)
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80
100
0
25
50
75
100
I LOAD (mA)
DS9263-09 March 2007
RT9263
Preliminary
Application Information
Output Voltage Setting
Referring to application circuits Figure 1 to Figure 4 the
output voltage of the switching regulator (VOUT1) can be
set with Equation (1).
R1
(1)
VOUT1 = (1+
) × 1.25V
R2
PRECAUTION 1: Improper probing to FB pin will
cause fluctuation at VOUT1. It may damage RT9263
and system chips because VOUT1 may drastically
rise to an over-rated level due to unexpected
interference or parasitics being added to FB pin.
Feedback Loop Design
PRECAUTION 2: Disconnecting R1 or short circuit
across R2 may also cause similar IC damage as
described in precaution 1.
Referring to application circuits Figure 1 to Figure 4. The
selection of R1 and R2 based on the trade-off between
quiescent current consumption and interference immunity
is stated below:
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Follow Equation (1)
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Higher R reduces the quiescent current (Path current
= 1.25V/R2), however resistors beyond 5MW are not
recommended.
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Lower R gives better noise immunity, and is less
sensitive to interference, layout parasitics, FB node
leakage, and improper probing to FB pins.
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A proper value of feed forward capacitor parallel with
R1 on Figure 1 to Figure 4 can improve the noise
immunity of the feedback loops, especially in an
improper layout. An empirical suggestion is around
100pF ~ 1nF for feedback resistors of MΩ, and 10nF ~
0.1μF for feedback resistors of tens to hundreds KΩ.
For applications without standby or suspend modes, lower
values of R1, and R2 are preferred. For applications
concerning the current consumption in standby or
suspend modes, the higher values of R1, and R2 are
needed. Such “ high impedance feedback loops” are
sensitive to any interference, which require careful layout
and avoid any interference, e.g. probing to FB pins.
PRECAUTION 3: When large R values were used
in feedback loops, any leakage in FB node may
also cause VOUT1 voltage fluctuation, and IC
damage. To be especially highlight here is when
the air moisture frozen and re-melt on the circuit
board may cause several mA leakage between IC
or component pins. So, when large R values are
used in feedback loops, post coating, or some
other moisture-preventing processes are
recommended.
VOUT1
Prober Parasitics
FB Pin
_
Q
+
R2
Layout Guide
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DS9263-09 March 2007
R1
A full GND plane without gap break.
VOUT1 to GND noise bypass − Short and wide connection
for C2 to Pin2 and Pin5.
VIN to GND noise bypass − Add a 100μF capacitor close
to L1 inductor, when VIN is not an idea voltage source.
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Minimized FB node copper area and keep far away from
noise sources.
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Minimized parasitic capacitance connecting to LX and
EXT nodes, which may cause additional switching loss.
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RT9263
Preliminary
Outline Dimension
D
D1
b1
A
C
B
C1
e
e
H
A
b
Symbol
b1
b
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
1.400
1.600
0.055
0.063
b
0.360
0.508
0.014
0.020
B
2.400
2.600
0.094
0.102
b1
0.406
0.533
0.016
0.021
C
3.937
4.250
0.155
0.167
C1
0.800
1.194
0.031
0.047
D
4.400
4.600
0.173
0.181
D1
1.397
1.700
0.055
0.067
e
1.400
1.600
0.055
0.063
H
0.356
0.430
0.014
0.017
5-Lead SOT-89 Surface Mount Package
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
8F, No. 137, Lane 235, Paochiao Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)89191466 Fax: (8862)89191465
Email: [email protected]
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DS9263-09 March 2007