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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 SOT89-5 Package
Applications
PDA Portable Instrument DSC
Ordering Information
RT9263 Package type X5 : SOT89-5 Operating temperature range C: Commercial standard C : Chip enable control E : Driver for external power devices
Pin Configurations
Part Number RT9263CCX5 (Plastic SOT89-5) Pin Configurations
TOP VIEW
5 4
1
2
3
1. 2. 3. 4. 5. 1. 2. 3. 4. 5.
CE VDD FB LX GND EXT VDD FB LX GND
RT9263ECX5 (Plastic SOT89-5)
TOP VIEW
5 4
Typical Application Circuit
1
2
3
VIN
+ 100pF VDD CE RT9263CCX5 LX GND FB R2 980K D1 1N5819 C2 1F + R1 1.6M L1 4.7H
100F 3.3V VOUT1
C1 100F
Fig. 1 RT9263CCX5 Typical Application for Portable Instruments below 400mA
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RT9263
Preliminary
VIN
+ 100pF VDD R1 1.6M Q1 NMOS R2 980K L1 4.7H D1 1N5819 C2 1F +
100F 3.3V VOUT1
RT9263ECX5
GND
LX EXT FB
C1 100F
Fig. 2 0.4A ~ 1A Output Current Application
Rm 0.05~0.1
Fig. 3 High Voltage Application (Rm should be added when IL > 100mA)
R2 C2 200K 1F
Fig.4 High Voltage Application with Shutdown Control
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2
+
Chip Enable
+
3.3/5V VIN
L1 100F 10H Q1 NMOS VDD
D1
RT9263CCX5 LX
CE GND FB
0.1F
R1 2.2M
+
+
3.3/5V VIN
L1 100F VDD EXT RT9263ECX5 LX GND FB 10H Q1 NMOS 0.1F
D1
R1 2.2M R2 C2 200K 1F
15V VOUT1
C1 100F
15V VOUT1
C1 100F
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Preliminary Function Block Diagram
RT9263
VDD _ FB 1.25V
RT9263CCX5
LX Loop Control Circuit Q1 NMOS R1 +
CE
GND
VDD
RT9263ECX5
EXT LX
1.25V
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_ +
FB
Loop Control Circuit
Q1 NMOS R1 GND
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RT9263
Pin Description
Pin No. RT9263CCX5 RT9263ECX5 -1 2 3 4 5 1 -2 3 4 5 Pin Name EXT CE VDD FB LX GND
Preliminary
Pin Function Output pin for driving external NMOS or NPN When driving an NPN, a resistor should be added for limiting base Chip enable RT9263CCX5 gets into shutdown mode when CE pin set to low. Input positive power pin of RT9263 Feedback input pin Internal reference voltage for the error amplifier is 1.25V. Pin for switching Ground
Absolute Maximum Ratings
Supply Voltage LX Pin Switch Voltage Other I/O Pin Voltages LX Pin Switch Current EXT Pin Driver Current Power Dissipation, PD @ TA = 25C SOT89-5 * Package Thermal Resistance SOT89-5, JA Operating Junction Temperature Storage Temperature Range 300C/W 150C -65C ~ +150C 0.5W -0.3V to 6V -0.3V to (VDD + 0.8V) -0.3V to (VDD + 0.3V) 2.5A 30mA
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Preliminary 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 CE Pin Trip Level Temperature Stability for FB, LFB, LBI Thermal Shutdown Thermal Shutdown Hysterises TS TSD TSD VLINE VLOAD ILIMIT Symbol VST VDD INO LOAD IOFF VREF FS DMAX Test Conditions IL = 1mA Start-up to IDD1 > 250A VIN = 1.5V, VOUT = 3.3V CE Pin = 0V, VIN = 4.5V Close Loop, VDD = 3.3V VDD = 3.3V VDD = 3.3V VDD = 3.3V VDD = 3.3V VDD = 3.3V VDD = 3.3V 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 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
RT9263
Max 1.05 6 --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
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RT9263
Typical Operating Charateristics
Efficiency
Preliminary
Efficiency
VOUT= 5.0V; TA = 25C
VOUT = 3.3V ; TA = 25C
No Load Current
90 80 70 60 140
No Load Current
TA = 25C VOUT = 3.3V
120 100
TA = 25C VOUT = 5.0V
IDD ( A)
IDD ( A) Refer to Application Circuit Fig.1
1 1.2 1.5 2 2.5 3
50 40 30 20 10 0
80 60 40 20 0 1
Refer to Application Circuit Fig.1
1.2 1.5 2 2.5 3 4
Input Voltage (V)
Input Voltage (V)
Start Up Voltage
1.4
Start Up Voltage
1.25 1.20 1.15
TA = 25C 1.3 VOUT = 3.3V Input Voltage (V)
1.2 1.1 1.0 0.9
TA = 25C VOUT= 5.0V
Input Voltage (V) Refer to Application Circuit Fig.1
1.10 1.05 1.00 0.95 0.90 0.85
0.8 0 20 40 60 80 100
0.80 0
Refer to Application Circuit Fig.1 ILOAD (mA) ILOAD (mA) in constant resistance load
25 50 75 100
ILOAD (mA) ILOAD (mA) in constant resistance load
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Preliminary Application Note
Output Voltage Setting Referring to application circuits Fig.1 to Fig.4, the output voltage of the switching regulator (VOUT1) can be set with Eq.1. R1 VOUT1 = (1 + ) x 1.25 V R2 Feedback Loop Design Referring to application circuits Fig.1 to Fig.4, The selection of R1 and R2 based on the trade-off between quiescent current consumption and interference immunity is stated below: * Follow Eq.1 * Higher R reduces the quiescent current (Path current = 1.25V/R2), however resistors beyond 5M 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 Fig.1 to Fig.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. Layout Guide
Prober Parasitics
_ Q +
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
Eq.1
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 A 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 R2
* 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
Package Information
Preliminary
D D1
A H
C
B
C1 e e
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 -0.800 4.400 -1.400 0.380 Max 1.600 0.520 2.600 0.533 4.250 -4.600 1.700 1.600 0.430
Dimensions In Inches Min 0.055 0.014 0.094 0.016 -0.031 0.173 -0.055 0.014 Max 0.063 0.020 0.102 0.021 0.167 -0.181 0.067 0.063 0.017
5-Lead SOT-89 Surface Mount
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Preliminary
RT9263
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RT9263
Preliminary
RICHTEK TECHNOLOGY CORP.
Headquarter
6F, No. 35, Hsintai Road, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5510047 Fax: (8863)5537749
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek-ic.com.tw
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