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Preliminary
RT9266
Tiny Package, High Efficiency, Step-up DC/DC Converter
General Description
The RT9266 is a compact, high efficiency, and low voltage step-up DC/DC converter with an Adaptive Current Mode PWM control loop, includes an error amplifier, ramp generator, comparator, switch pass element and driver in which providing a stable and high efficient operation over a wide range of load currents. It operates in stable waveforms without external compensation. The low start-up input voltage below 1V makes RT9266 suitable for 1 to 4 battery cells applications of providing up to 300mA output current. The 450KHz high switching rate minimized the size of external components. Besides, the 17A low quiescent current together with high efficiency maintains long battery lifetime. The output voltage is set with two external resistors. Both internal 2A switch and driver for driving external power devices (NMOS or NPN) are provided.
Features
1.0V Low Start-up Input Voltage High Supply Capability to Deliver 3.3V 100mA with 1 Alkaline Cell 17A Quiescent (Switch-off) Supply Current Zero Shutdown Mode Supply Current 90% Efficiency 450KHz Fixed Switching Frequency Providing Flexibility for Using Internal and External Power Switches Small SOT-26 & SOT89-5 Package
Applications
PDA DSC LCD Panel RF-Tags MP3 Portable Instrument Wireless Equipment
Pin Configurations
Part Number RT9266CE (Plastic SOT-26) Pin Configurations
TOP VIEW
6 5 4
Ordering Information
RT9266 Package Type E : SOT-26 X5 : SOT89-5 Operating Temperature Range C: Commercial Standard
1
2
3
1. 2. 3. 4. 5. 6.
CE EXT GND LX VDD FB
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.
RT9266CX5 (Plastic SOT89-5)
5
4
1
2
3
TOP VIEW 1. CE 2. VDD 3. FB 4. LX 5. GND
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February 2003
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RT9266
Typical Application Circuit
Preliminary
L1 VIN + CE EXT
3.1V ~ 5V for 12V 2.8V ~ 5V for 9V L1 VIN + C5 100F RVDD 100 CVDD 1F VDD CE EXT LX FB RM 0.22 Q1 NMOS C4 0.1F 4.7H GND
D1 1N5819 VOUT 3.3V/5V R1 1.6M/3M + C1 100F
C3 100F
3.3 ~ 10H
C2 1F VDD
RT9266
GND
LX FB
R2 980K/1M
Fig. 1 RT9266 Typical Application for Portable Instruments
D1 1N5819
RT9266
Fig. 2 RT9266 High Voltage Applications
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2
+
R1 860K/620K C2 R2 1F 100K
12V/9V 300mA C1 100F
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Preliminary
RT9266
L1 VIN + CE
VIN 3.3V/5V C1 1F R3 100 CE
D1 1N5819
C5 100F
3.3 ~ 10H
VOUT 3.3V/5V
C2 1F VDD LX EXT FB Q1 NMOS R2 980K/1M R1 1.6M/3M +
R1 620K R2 100K VOUT3 -9V 10mA C5 10F
RT9266
GND
C1 100F
Fig. 3 RT9266 for Higher Current Applications
L1 C2 3.3 ~ 10H 10F Q1 NMOS VDD LX FB EXT C6 C7 1F 0.1F C8 1F C3 10F
VOUT2 +18V 10mA VOUT1 +9V 100mA
C4 10F
RT9266
GND
Fig. 4 RT9266 for Multi-Output Applications
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RT9266
Pin Description
Pin No. RT9266CX5 RT9266CE 1 1 2 5 4 2 3 3 4 5 6 Pin Name CE EXT GND LX VDD FB
Preliminary
Pin Function Chip enable RT9266 gets into shutdown mode when CE pin set to low. Output pin for driving external NMOS Ground Pin for switching Input positive power pin of RT9266 Feedback input pin Internal reference voltage for the error amplifier is 1.25V.
Function Block Diagram
VDD
RT9266
EXT LX
FB VDD 1.25 V R2 CE Q3 NMOS
_ +
Loop Control Circuit
Q1 NMOS R1
Shut Down Over Temp. Detector GND
Test Circuit
I (VIN) VIN
L1 C3 100F 10H R3 +
D1 1N5819 VOUT 3.3V/5V C1 100F C5 106
A
VDD CE EXT
R1 1.6M/3M
C4 102
RT9266
GND
LX FB R2 980K/1M
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4
+
A I (VDD)
C2 1F
100
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Preliminary Absolute Maximum Ratings
Supply Voltage LX Pin Switch Voltage Other I/O Pin Voltages LX Pin Switch Current EXT Pin Driver Current * Package Thermal Resistance SOT-26, JC SOT-89-5, JC Operating Junction Temperature Storage Temperature Range
RT9266
- 0.3V to 7V - 0.3V to (VDD + 0.8V) - 0.3V to (VDD + 0.3V) 2.5A 200mA 145C/W 45C/W 125C - 65C ~ +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 Frequency 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 Vout Thermal Shutdown Thermal Shutdown Hysterises Ts TSD TSD VLINE VLOAD ILIMIT Symbol VST VDD INO LOAD IOFF VREF FS DMAX Test Conditions IL = 1mA VDD pin voltage 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 Min -2 ---1.225 --------0.4 ---Typ 0.98 -75 17 0.01 1.25 450 95 0.3 2 5 5 10 0.25 0.8 50 165 10 Max 1.05 6.5 --1 1.275 --------1.2 ---*
Units V V A A A V KHz % A mV/V mV/mA V ppm/C C C
ISWITCH OFF VIN = 6V
* Note: The CE 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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February 2003
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RT9266
(Refer to Test Circuit)
Preliminary
Typical Operating Characteristics
Efficiency vs. Output Current
95
VOUT = 5V, TA = 25C
Efficiency vs. Output Current
95
VOUT = 3.3V, TA = 25C
90
90
Efficiency (%)
Efficiency (%)
85
VIN = 4.5V VIN = 4.0V VIN = 3.5V VIN = 3.0V VIN = 2.5V VIN = 2.0V
85
VIN = 3.0V VIN = 2.5V VIN = 2.0V
80
80
75
VIN = 1.5V
75
VIN = 1.5V VIN = 1.0V
70 000
001
010
100
1000
70 0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Input Current I(VDD) vs. Output Current
250
21 20
Input Current I(VDD) vs. Input Voltage
VOUT = 5V @ no load
VIN = 3V, VOUT = 5V
Input Current ( A)
Input Current ( A)
200
19 18 17 16 15
150
100
50
0 0.01 0.1 1 10 100 1000
2.5
3.0
3.5
4.0
4.5
5.0
Output Current (mA)
Input Voltage (V)
Input Current I(VIN) vs. Input Voltage
180 150
Input Current I(VIN) vs. Input Voltage
90 80
VOUT = 5V @ no load
VOUT = 3.3V @ no load
Input Current ( A)
120 90 60 30 0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Input Current ( A)
70 60 50 40 30 1.5 2 2.5 3 3.5
Input Voltage (V)
Input Voltage (V)
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Preliminary
RT9266
Start Up Voltage vs. Output Current
600
Swichting Frequency vs. VDD Pin Voltage
VIN = 2.4V ~ 2.8V VIN = 3V ~ 5.6V
1.6 1.4
Switching Rate Frequency (KHz)
VOUT = 3.3V
500
Start Up Voltage (V)
1.2 1.0 0.8 0.6 0.4 0.2
400
300
VIN = 1.2V ~ 2.2V
200
100 0 1 2 3 4 5 6
0.0 0 30 60 90 120
(In C.R. mode)
150
180
210
VDD Pin Voltage (V)
Output Current (mA)
LX Pin Wave Form & Output Ripple
LX Wave Form LX Wave Form Output Ripple
VIN = 1V, VOUT = 3.3V @ 100mA
LX Pin Wave Form & Output Ripple
VIN = 1V, VOUT = 3.3V @ 10mA
Output Ripple
Time (1s/Div)
Time (1s/Div)
LX Pin Wave Form & Output Ripple
LX Wave Form LX Wave Form Output Ripple
VIN = 2V, VOUT = 3.3V @ 200mA
LX Pin Wave Form & Output Ripple
VIN = 2V, VOUT = 3.3V @ 10mA
Output Ripple
Time (1s/Div)
Time (1s/Div)
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February 2003
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RT9266
Preliminary
LX Pin Wave Form & Output Ripple
LX Wave Form
VIN = 3V, VOUT = 3.3V @ 200mA
LX Pin Wave Form & Output Ripple
LX Wave Form Output Ripple
VIN = 3V, VOUT = 3.3V @ 10mA
Output Ripple
Time (1s/Div)
Time (1s/Div)
LX Pin Wave Form & Output Ripple
LX Wave Form
VIN = 2V, VOUT = 5V @ 200mA
LX Pin Wave Form & Output Ripple
LX Wave Form Output Ripple
VIN = 2V, VOUT = 5V @ 20mA
Output Ripple
Time (1s/Div)
Time (1s/Div)
LX Pin Wave Form & Output Ripple
LX Wave Form
VIN = 3V, VOUT = 5V @ 200mA
LX Pin Wave Form & Output Ripple
LX Wave Form Output Ripple
VIN = 3V, VOUT = 5V @ 20mA
Output Ripple
Time (1s/Div)
Time (1s/Div)
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DS9266-02 February 2003
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Preliminary
RT9266
LX Pin Wave Form & Output Ripple
LX Wave Form LX Wave Form Output Ripple Time (1s/Div)
VIN = 4.5V, VOUT = 5V @ 200mA
LX Pin Wave Form & Output Ripple
VIN = 4.5V, VOUT = 5V @ 20mA
Output Ripple
Time (1s/Div)
Transient Response
VIN = 2V, VOUT = 3.3V IOUT = 10mA 200mA
Transient Response
VIN = 3V, VOUT = 3.3V IOUT = 10mA 200mA
Output Transient Voltage
Time (50s/Div)
Output Transient Voltage
Time (50s/Div)
Transient Response
VIN = 3V, VOUT = 5V IOUT = 10mA 200mA
Transient Response
VIN = 4.5V, VOUT = 5V IOUT = 10mA 200mA
Output Transient Voltage
Time (50s/Div)
Output Transient Voltage
Time (50s/Div)
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February 2003
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RT9266
Application Note
Preliminary
Output Voltage Setting Referring to application circuits, the output voltage of the switching regulator (VOUT) can be set with Eq.1.
VOUT1 = (1 + R1 ) x 1.25 V R2
Layout Guide * A full GND plane without gap break. * VDD to GND noise bypass - Short and wide connection for the 1F MLCC capacitor between Pin5 and Pin3. * VIN to GND noise bypass - Add a 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. Board Layout Example (2-Layer Board) (Refer to Application Circuit Fig. 2 for the board)
Eq.1
Feedback Loop Design Referring to application circuits, 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.
VOUT1
Prober Parasitics
_ Q +
R1 FB Pin R2
* A proper value of feed forward capacitor parallel with R1 can improve the noise immunity of the feedback loops, especially in an improper layout. An empirical suggestion is around 0~33pF 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 pin.
-
Top Layer -
- Bottom Layer -
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Preliminary Package Information
RT9266
H D L C B
b A A1 e
Symbol A A1 B b C D e H L
Dimensions In Millimeters Min 0.889 -1.397 0.356 2.591 2.692 0.838 0.102 0.356 Max 1.295 0.152 1.803 0.559 2.997 3.099 1.041 0.254 0.610
Dimensions In Inches Min 0.035 -0.055 0.014 0.102 0.106 0.033 0.004 0.014 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024
SOT- 26 Surface Mount Package
DS9266-02
February 2003
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RT9266
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 -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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DS9266-02 February 2003
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Preliminary
RT9266
DS9266-02
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RT9266
Preliminary
RICHTEK TECHNOLOGY CORP.
Headquarter
5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
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.com
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