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Preliminary
RT9263
High Efficiency, Low Supply Current, Step-Up DC/DC Converter
General Description
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. 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 17A low quiescent current together with high efficiency maintains long battery lifetime.
Features
1.0V Low Start-up Input Voltage High Supply Capability to Deliver 3.3V 100mA with 1V Input Voltage 17A 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
Applications
PDA Portable Instrument DSC
Ordering Information
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
Pin Configurations
(TOP VIEW)
EN VDD FB 1 GND
5
2 3 4 LX
Note : RichTek Pb-free and Green products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 100%matte tin (Sn) plating.
RT9263CCX5 SOT-89-5
EXT
1
5
GND
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.
VDD FB
2 3 4 LX
RT9263ECX5 SOT-89-5
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RT9263
Typical Application Circuit
Preliminary
VIN VDD EN RT9263CCX5 EXT LX GND FB 1N5819
+
C3 100uF C4 100pF R1 1.6M L1 4.7uF D1 3.3V VOUT C1 100uF
R2 C2 980K 1uF
Figure 1. RT9263CCX5 Typical Application for Portable Instruments below 400mA
VIN VDD RT9263ECX5 LX EXT GND FB R2 980K C4 100pF R1 1.6M
L1 4.7uF 1N5819 Q1 D1 N MOS
+
C3 100uF
3.3V VOUT1
C2 1uF
C1 100uF
Figure 2. 0.4A to 1A Output Current Application
5V VIN
L1 C4 100uF 10uF VDD RT9263ECX5 EXT LX GND FB Rm 0.05 ~ 0.1 Q1 N MOS C3 0.1uF
D1
R1 2.2M
+
15V VOUT1
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
Preliminary
RT9263
5V VIN
L1 C4 100uF VDD RT9263ECX5 LX FB GND C3 0.1uF 10uF Q1 N MOS
D1
Chip Enable
R1 2.2M
+
15V VOUT1
EN
C2 R2 200K 1uF
C1 100uF
Figure 4. High Voltage Application with Shutdown Control
Function Block Diagram
RT9263CCX5 VDD FB EN 1.25V
+
LX Q1 N MOS R1 GND
Loop Control Circuit
VDD
RT9263ECX5 EXT LX
FB 1.25V
+ Loop Control Circuit
Q1 N MOS R1 GND
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RT9263
Functional Pin Description
Pin No. RT9263CCX5 RT9263ECX5 -1 2 3 4 5 1 -2 3 4 5 EXT EN VDD FB LX GND
Preliminary
Pin Name Pin Function Output Pin for Driving External NMOS or NPN When driving an NPN, a resistor should be added for limiting base Chip Enable Pin (Active High) Input Positive Power Pin of RT9263 Feedback Input Pin Internal reference voltage for the error amplifier is 1.25V. Pin for Switching Ground
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DS9263-09 March 2007
Preliminary Absolute Maximum Ratings
RT9263
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 = 25C SOT89-5 ------------------------------------------------------------------------------------------------------------- 0.5W Package Thermal Resistance SOT89-5, JA ---------------------------------------------------------------------------------------------------------------------------------------------------- 300C/W Operating Junction Temperature ------------------------------------------------------------------------------- 150C Storage Temperature Range ------------------------------------------------------------------------------------ -65C to +150C
Electrical Characteristics
(VIN = 1.5V, VDD set to 3.3V, Load Current = 0, TA = 25C, unless otherwise specified)
Parameter Start-UP Voltage Operating VDD Range No Load Current I (VIN) Switch-off Current I (VDD) Shutdown Current I (VIN) Feedback Reference Voltage Switching Rate Maximum Duty LX ON Resistance Current Limit Setting EXT ON Resistance to VDD EXT ON Resistance to GND Line Regulation Load Regulation EN Pin Trip Level
Symbol VST VDD INO LOAD
Test Conditions IL = 1mA Start-up to IDD1 > 250A VIN = 1.5V, VOUT = 3.3V
Min -0.8 ---1.225 --------0.2 ----
Typ 0.98 -47 17 0.1 1.25 550 92 0.25 2 40 30 10 0.25 0.8 50 165 10
Max 1.05 6.5 --1 1.275 --------1.4 ---*
Units V V A A A V kHz % A mV/V mV/mA V ppm/C C C
ISWITCH OFF VIN = 6V IOFF VREF FS DMAX EN Pin = 0V, VIN = 4.5V Close Loop, VDD = 3.3V VDD = 3.3V VDD = 3.3V VDD = 3.3V ILIM VDD = 3.3V VDD = 3.3V VDD = 3.3V VLINE VLOAD VIN = 1.5 ~ 2.5V, IL = 1mA VIN = 2.5V, IL = 1 ~ 100mA VDD = 3.3V Guaranteed by Design Guaranteed by Design Guaranteed by Design
Temperature Stability for FB, LFB, LBI TS Thermal Shutdown Thermal Shutdown Hysterises TSD TSD
* 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.
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RT9263
Efficiency for 3.3V Output
100
Preliminary
Typical Operating Characteristics
Efficiency for 5.0V Output
100
TA = 25C
90 80
90 80
TA = 25C
Efficiency (%)
70 60 50 40 30
Efficiency (%)
VIN = 3.0V 2.5V 2.0V 1.5V 1.2V 1.0V Refer to Application Circuit Figure 1
0.1 1 10 100 1000
70 60 50 40 30
VIN = 4.0V 3.0V 2.0V 1.5V 1.2V 1.0V
20 0.01
Refer to Application Circuit Figure 1 20 0.01 0.1 1 10
100
1000
I LOAD (mA)
I LOAD (mA)
No Load Current
90 80 70
100 140
No Load Current
TA = 25C VOUT = 3.3V
120
TA = 25C VOUT = 5.0V
60
I DD (uA)
I DD (uA)
Refer to Application Circuit Figure 1
50 40 30
80 60 40
20 10 0 1 1.2 1.5 2 2.5 3
20
Refer to Application Circuit Figure 1
0 1 1.2 1.5 2 2.5 3 4
Input Voltage (V)
Input Voltage (V)
Start Up Voltage
1.4 1.3
Start Up Voltage
1.25 1.20 1.15
TA = 25C VOUT = 3.3V
TA = 25C VOUT = 5.0V
Input Voltage (V)
Input Voltage (V)
Refer to Application Circuit Figure 1
1.2 1.1 1.0 0.9
1.10 1.05 1.00 0.95 0.90 0.85 0.80
Refer to Application Circuit Figure 1
0 25 50 75 100
0.8 0 20 40 60 80 100
I LOAD (mA)
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I LOAD (mA)
DS9263-09 March 2007
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+ ) x 1.25V R2 Feedback Loop Design 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: Follow Equation (1) Higher R reduces the quiescent current (Path current = 1.25V/R2), however resistors beyond 5MW are not recommended. Lower R gives better noise immunity, and is less sensitive to interference, layout parasitics, FB node leakage, and improper probing to FB pins. 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 M, and 10nF ~ 0.1F for feedback resistors of tens to hundreds K. 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.
RT9263
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. PRECAUTION 2: Disconnecting R1 or short circuit across R2 may also cause similar IC damage as described in precaution 1. 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 R1 FB Pin _ Q + R2
Prober Parasitics
Layout Guide 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 100F capacitor close to L1 inductor, when VIN is not an idea voltage source. Minimized FB node copper area and keep far away from noise sources. Minimized parasitic capacitance connecting to LX and EXT nodes, which may cause additional switching loss.
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RT9263
Outline Dimension
Preliminary
D D1 b1
A
C
B
C1 e e
H
A
b
b1
b
Symbol A b B b1 C C1 D D1 e H
Dimensions In Millimeters Min 1.400 0.360 2.400 0.406 3.937 0.800 4.400 1.397 1.400 0.356 Max 1.600 0.508 2.600 0.533 4.250 1.194 4.600 1.700 1.600 0.430
Dimensions In Inches Min 0.055 0.014 0.094 0.016 0.155 0.031 0.173 0.055 0.055 0.014 Max 0.063 0.020 0.102 0.021 0.167 0.047 0.181 0.067 0.063 0.017
5-Lead SOT-89 Surface Mount Package
Richtek Technology Corporation
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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