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RT8003 600mA, 2MHz, High-Efficiency Synchronous Buck PWM Converter
General Description
The RT8003 is a high-efficiency synchronous buck PWM converter with integrated P-Channel and N-Channel power MOSFET switches. Capable of delivering 600mA output current over a wide input voltage range of 2.4V to 5.5V, the RT8003 is ideally suited for portable applications powered by a single Li-Ion battery or by 3-cell NiMH/NiCd batteries. The device operates at 2MHz PWM switching fixed frequency, can use smaller CIN, COUT capacitor and inductor. The RT8003 integrates two low RDS(ON) 230m and 180m of high- and low-side switching MOSFETs to reduce board space, as only resistors and capacitors along with one inductor are required externally for operation. The RT8003 has adjustable output range down to 0.5V. The other features include internal soft-start, chip enable, overtemperature and over-current protections. It is available in a space-saving VDFN-10L 3x3 package.
Features
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2.4V to 5.5V Input Voltage Range Adjustable Output from 0.5V to VIN Guaranteed 600mA Output Current Accurate Reference : 0.5V (1.5%) Up to 90% Conversion Efficiency Typical Quiescent Current : 200A Integrated Low RDS(ON) High- and Low-Side Power MOSFET Switches: 230m and 180m Current Mode PWM Operation Fixed Frequency : 2MHz 100% Maximum Duty Cycle for Lowest Dropout Internal Soft-Start No Schottky Diode Required Over-Temperature and Over-Current Protection Small 10-Lead VDFN 3x3 Package RoHS Compliant and 100% Lead (Pb)-Free
Applications
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Ordering Information
RT8003 Package Type QV : VDFN-10L 3x3 (V-Type) Operating Temperature Range P : Pb Free with Commercial Standard
Note : RichTek Pb-free 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.
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Battery-Powered Equipments Low Power CPU and DSP Supplies Digital Cameras and Hard Disks Protable Instruments and Notebook Computers Celluar Phones, PDAs, and Handheld PCs USB-Based DSL Modems and Other Network Interface Cards
Pin Configurations
(TOP VIEW)
LX VDD NC NC EN
1 2 3 4 5 10 9
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.
GND
GND GND 8 GND 7 COMP FB
VDFN-10L 3x3
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RT8003
Typical Application Circuit
VIN 2.4V to 4.2V CIN 1uF Chip Enable 5 2 VDD EN RT8003 7 6 R2 7.15k LX 1 LOUT 2.2uH VOUT 1.2V/600mA R1 10k COUT 1uF
COMP FB C COMP GND 10nF 8, 9, 10
Recommended component selection for Typical Application Circuit. VOUT (V) 0.5 1 1.2 1.8 2.5 3.3 VIN (V) 2.4 to 3.3 2.4 to 3.6 2.4 to 4.2 2.4 to 5.5 3.3 to 5.5 4.2 to 5.5 CIN (uF) 1 1 1 1 1 1 COUT (uF) 1/2.2 1/2.2 1/2.2 1/2.2 1/2.2 1/2.2 LOUT (uH) 2.2/1 2.2/1 2.2/1 2.2/1 2.2/1 2.2/1 R1 (k) 10 10 10 10 10 10 R2 (k) Open 10 7.15 3.83 2.49 1.78 CCOMP (nF) 10 10 10 10 10 10
Suggested Inductors Component Supplier ABC Sumida TDK SR0302 CDRH2D14 VLP4612 Series Inductance (H) 1 2.2 2.2 1 2.5 ESR (m) 60 90 94 110 170 Current Rating (mA) 2100 1650 1000 1500 1100 Dimensions (mm) 3x2.8x2.5 3.2x3.2x1.55 4.6x3.4x1.2
Suggested Capacitors For C IN and COUT Component Supplier TDK Panasonic TAIYO YUDEN Part No. C1608X5R1A105M C1608X5R1A225M ECJ1VB0J105M ECJ1VB0J225M JMK107BJ105M JMK107BJ225M Capacitance (uF) 1 2.2 1 2.2 1 2.2 Case Size 0603 0603 0603 0603 0603 0603
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Functional Pin Description
No 1 2 3,4 5 6 7 Pin Name Pin Function LX VDD NC EN FB COMP Internal Power MOSFET Switches Output. Connect this pin to the inductor. Power Input Supply. Input voltage which supplies current to the output pin. Connect this p in with a low-ESR capacitor to GND No Internal Connection Chip Enable (Active High). Logic low shuts down the converter. Floating this pin is forbidden. Switcher Feedback Voltage. This pin is the inverting input of the error amplifier. FB senses the switcher output through an external resistor divider network. FB regulation voltage is 0.5V. Compensation Input. This pin is the output of the internal error amplifier. Connect an external capacitor to compensate the regulator controlled loop. Ties the pin directly to the cathode terminal of C IN and COUT and ground plane with the lowest impedance. Signal and Common Ground (Exposed thermal pad is connected to GND). The GND pad area should be as large as possible and using many vias to conduct the heat into the buried GND plate of PCB layer. All small-signal, compensation and feedback components should connect to this pin.
8,9,10
GND
Function Block Diagram
EN VDD
Shutdown Control Oscillator COMP VREF
Slope Compensation
Current Limit Detector
Over Temperature Detector
Current Sense
PWM Comparator
+
Error Amplifier
+
Control Logic
Driver
LX
FB
-
Zero Detector
GND
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Absolute Maximum Ratings
l
(Note 1)
Supply Voltage ----------------------------------------------------------------------------------------------------0.3V to 6V l LX Voltage --------------------------------------------------------------------------------------------------------- -0.3V to (VDD + 0.3V) l Power Dissipation, PD @ TA = 25C VDFN-10L 3x3 ----------------------------------------------------------------------------------------------------1.923W l Package Thermal Resistance (Note 4) VDFN-10L 3x3, JA -----------------------------------------------------------------------------------------------52C/W l Junction Temperature -------------------------------------------------------------------------------------------150C l Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------260C l Storage Temperature Range ----------------------------------------------------------------------------------- -65C to 150C l ESD Susceptibility (Note 2) HBM (Human Body Mode) -------------------------------------------------------------------------------------2kV MM (Machine Mode) --------------------------------------------------------------------------------------------200V
Recommended Operating Conditions
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(Note 3)
Supply Voltage ---------------------------------------------------------------------------------------------------2.4V to 5.5V Enable Input Voltage, VEN -------------------------------------------------------------------------------------0V to 5.5V Ambient Temperature Range ---------------------------------------------------------------------------------- -40C to 85C Junction Temperature Range ----------------------------------------------------------------------------------0C to 125C
Electrical Characteristics
(VDD = 3.3V, TA = 25C, unless otherwise specified)
Parameter Supply Current Quiescent Current Shutdown Current Reference Reference Voltage Oscillator Switching Frequency Range Maximum Duty Cycle Output Voltage Line Regulation Load Regulation Power Switches RDS(ON) of P-Channel MOSFET RDS(ON) of N-Channel MOSFET Current Limit
Symbol
Test Conditions
Min
Typ
Max
Units
IQ ISHDN
VEN = 3.3V, VFB = VREF + 0.15V, IOUT = 0mA VEN = 0V
---
200 0.01
400 1
A A
VREF
0.4925
0.5
0.5075
V
fOSC DC VDD = VOUT
1.7 100
2.0 --
2.3 --
MHz %
VDD = 2.4V to 5.5V, ILOAD = 100mA 10mA < ILOAD < 600mA
---
---
+1.5 +1.5
% %
R P_FET R N_FET ILIMIT
VDD = 3.3V, ILX = 300mA VDD = 3.3V, ILX = -300mA VDD = 3.3V, VFB = VREF - 0.15V
----
230 180 1.8
----
m m A
To be continued
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Parameter Logic Input EN Threshold Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSD TSD --180 20 --C C Logic-Low Voltage VIL Logic-High Voltage VIH VDD = 2.4V to 5.5V, Shutdown VDD = 2.4V to 5.5V, Enable -1.5 --0.4 -V Symbol Test Conditions Min Typ Max Units
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. JA is measured in the natural convection at TA = 25C on a high effective thermal conductivity test board of JEDEC 51-7 thermal measurement standard.
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Typical Operating Characteristics
Output Voltage Deviation vs. Output Current
0.10% 0.1
Output Voltage Deviation vs. Temperature
0.40% 0.4
Output Voltage Deviation (%)
Output Voltage Deviation (%)
0 100 200 300 400 500 600 700 800
0.00% 0 -0.10% -0.1 -0.20% -0.2 -0.30% -0.3 -0.40% -0.4 -0.50% -0.5 -0.60% -0.6 -0.70% -0.7
0.20% 0.2 0.00% 0 -0.20% -0.2 -0.40% -0.4 -0.60% -0.6 -0.80% -0.8 -1.00% -1.0 -1.20% -1.2 -1.40% -1.4 -1.60% -1.6 -1.80% -1.8 -50 -25 0 25 50 75 100 125 150
Output Current (mA)
Temperature (C)
Efficiency vs. Output Current
100% 100 90% 90 100% 100
Efficiency vs. Temperature
90% 90 80% 80 70% 70
VIN = 3.3V, VOUT = 1.2V
80 80%
Efficiency (%)
70% 70 60% 60 50% 50 40% 40 30% 30 20% 20 10% 10 0% 0 1 10 100 1000
Efficiency (%)
60% 60 50% 50 40% 40 30% 30 20% 20 10% 10 0% 0 -50 -25 0 25 50 75 100 125 150
VIN = 3.3V, VOUT = 1.2V, IOUT = 200mA
Output Current (mA)
Temperature (C)
Frequency vs. Input Voltage
2.15 2.1 2.05 2
Frequency vs.Temperature
Frequency (MHz)
2.05 2 1.95 1.9 1.85 2.5 3 3.5 4 4.5 5 5.5
Frequency (MHz)
1.95 1.9 1.85 1.8 1.75 -50 -25 0 25 50 75 100 125
Input Voltage(V)
Temperature (C)
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Quiescent Current vs. Input Voltage
300 250
Quiescent Current vs. Temperature
VIN = 3.3V, VFB = 0.65V
VFB = 0.65V
Quiescent Current (uA)
Quiescent Current (uA)
2.5 3 3.5 4 4.5 5 5.5
250 200 150 100 50 0
200
150
100
50
0 -50 -25 0 25 50 75 100 125
Input Voltage(V)
Temperature (C)
VREF vs. Temperature
0.52 0.515 0.51 0.52 0.515 0.51
VREF vs. Input Voltage
V REF (V)
0.505 0.5 0.495 0.49 0.485 0.48 -50 -25 0 25 50 75 100 125
V REF (V)
0.505 0.5 0.495 0.49 0.485 0.48 2.5 3 3.5 4 4.5 5 5.5
Temperature (C)
Input Voltage (V)
Current Limit vs. Input Voltage
3 2.5
Load Transient Response
VIN = 3.3V, VOUT = 1.2V IOUT = 50mA to 600mA
Current Limit (A)
2 1.5 1 0.5 0 2.5 3 3.5 4 4.5 5 5.5
Output Voltage
(50mV/Div)
Load Current
(200mA/Div)
Input Voltage (V)
Time (250s/Div)
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Steady State
VIN = 3.3V, VOUT = 1.2V, IOUT = 0mA, COUT = 1uF
Steady State
VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA, COUT = 1uF
Output Voltage
(10mV/Div)
Output Voltage
(10mV/Div)
(1V/Div)
VLX
VLX
(1V/Div)
Time (25s/Div)
Time (250ns/Div)
Soft Start Function
Output Voltage
(500mV/Div)
(2V/Div)
VEN Input Current
(200mA/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA
Time (500s/Div)
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Application Information
RT8003 is a pulse-width-modulated (PWM) step-down DCDC converter. Capable of delivering 600mA output current over a wide input voltage range from 2.4V to 5.5V. The RT8003 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy terminals. Chip Enable/Disable and Soft Start Four operational modes are available: PWM, PSM, LowDrop-Out and shut-down modes. Pulling EN pin lower than 0.4V shuts down the RT8003 and reduces its quiescent current to 1A. Pulling EN pin higher than 1.5V enables the RT8003 and initiates the softstart cycle. RT8003 has internal soft-start that can reduce the Inrush Current during the rising of Output Voltage. PWM Operation During normal operation, the RT8003 regulates output voltage by switching at a constant frequency transferring the power to the load in each cycle by PWM. The RT8003 uses a slope-compensated, current-mode PWM controller capable of achieving 100% duty cycle. At each rising edge of the internal oscillator, the Control Logic cell sends a PWM ON signal to the Driver cell to turn on internal PMOSFET. This allows current to ramp up through the inductor to the load, and stores energy in a magnetic field. The switch remains on until either the current-limit is tripped or the PWM comparator signals for the output in regulation. After the switch is turned off, the inductor releases the magnetic energy and forces current through the N-MOSFET synchronous rectifier to the output-filter capacitor and load. The output-filter capacitor stores charge when the inductor current is above the average output current and releases charge when the inductor current is below the average current to smooth the output voltage across the load. A Zero Detector monitors inductor current by sensing v oltage drop across the N-MOSFET synchronous rectifier when it turns on. The N-MOSFET turns off and allows the converter entering discontinuous conduction mode when the inductor current decreases to zero. The zero current detection on threshold is about 80mA.This reduces conduction loss and increase power conversion efficiency at light load condition.
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PSM Operation Consequently, the converter will enter pulse-skipping mode (PSM) during extreme light load condition or when modulation index (VOUT /VIN) is extreme low. This could reduce switching loss and further increase power conversion efficiency. Over Current Protection The RT8003 continuously monitors the inductor current by sensing the voltage across the P-MOSFET when it turns on. When the inductor current is higher than current limit threshold (1.8A typical), OCP activates and forces the P-MOSFET turning off to limit inductor current cycle by cycle.But it will shut down when the VOUT trip the UV protection. Output Voltage Setting and Feedback Network The output voltage can be set from VREF to VIN by a voltage divider as: the internal VREF is 0.5V with 1.5% accuracy. In practical application, keep R1 = 10k respectively and choose appropriate R2 according to the required output voltage. Inductor Selection The output inductor is suggested as the table of suggested inductors for optimal performance. Make sure that the inductor will not saturate over the operation conditions including temperature range, input voltage range, and maximum output current. If possible, choose an inductor with rated current higher than 2A so that it will not saturate even under short circuit condition. Input Capacitor Selection The input capacitor can filter the input peak current and noise at input voltage source. The capacitor with low ESR (effective series resistance) provides the small drop voltage to stabilize the input voltage during the transient loading. For input capacitor selection, the ceramic capacitors larger than 1F is recommend. The capacitor must conform to the RMS current requirement. The maximum RMS ripple current is calculated as : IRMS = IOUT(MAX) VOUT (VIN - VOUT) VIN
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RT8003
Output Capacitor Selection The capacitor' s ESR determines the output ripple voltage and the initial voltage drop following a high slew-rate transient' s edge. Typically, if the ESR requirement is satisfied, the capacitance is adequate to filtering. The output ripple voltage can be calculated as:
VOUT = IC (ESR + 1 ) 8 x COUT x fOSC
LX VIN R4 C1 EN VDD RT8003 R1 FB C3 COMP GND C2 R2 L1 VOUT
Where f OSC = operating frequency, COUT = output capacitance and IC = IL = ripple current in the inductor. The ceramic capacitor with low ESR value provides the low output ripple and low size profile. Connect a 1F/2.2F ceramic capacitor at output terminal for good performance and place the input and output capacitors as close as possible to the device. Layout Considerations Follow the PCB layout guidelines for optimal performance of RT8003. 1. For the main current paths as indicated in bold lines in Figure 1, keep their traces short and wide. 2. Put the input capacitor as close as possible to the device pins (VDD and GND). 3. LX node is with high frequency voltage swing and should be kept small area. Keep analog components away from LX node to prevent stray capacitive noise pick-up. 4. Connect feedback network behind the output capacitors. Keep the loop area small. Place the feedback components near the RT8003. 5.Connect all analog grounds to a command node and then connect the command node to the power ground behind the output capacitors. 6. An example of 2-layer PCB layout is shown in Figure 2 to Figure 3 for reference.
Figure 1
Figure 2. Top Layer
Figure 3. Bottom Layer
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Outline Dimension
D2
D
L
E
E2 SEE DETAIL A
1
e A A1 A3
b
2
1
2
1
DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated.
Symbol A A1 A3 b D D2 E E2 e L
Dimensions In Millimeters Min 0.800 0.000 0.175 0.180 2.950 2.300 2.950 1.500 0.500 0.350 0.450 Max 1.000 0.050 0.250 0.300 3.050 2.650 3.050 1.750
Dimensions In Inches Min 0.031 0.000 0.007 0.007 0.116 0.091 0.116 0.059 0.020 0.014 0.018 Max 0.039 0.002 0.010 0.012 0.120 0.104 0.120 0.069
V-Type 10L DFN 3x3 Package
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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RT8003 600mA, 2MHz, High-Efficiency Synchronous Buck PWM Converter
General Description
The RT8003 is a high-efficiency synchronous buck PWM converter with integrated P-Channel and N-Channel power MOSFET switches. Capable of delivering 600mA output current over a wide input voltage range of 2.4V to 5.5V, the RT8003 is ideally suited for portable applications powered by a single Li-Ion battery or by 3-cell NiMH/NiCd batteries. The device operates at 2MHz PWM switching fixed frequency, can use smaller CIN, COUT capacitor and inductor. The RT8003 integrates two low RDS(ON) 230m and 180m of high- and low-side switching MOSFETs to reduce board space, as only resistors and capacitors along with one inductor are required externally for operation. The RT8003 has adjustable output range down to 0.5V. The other features include internal soft-start, chip enable, overtemperature and over-current protections. It is available in a space-saving VDFN-10L 3x3 package.
Features
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2.4V to 5.5V Input Voltage Range Adjustable Output from 0.5V to VIN Guaranteed 600mA Output Current Accurate Reference : 0.5V (1.5%) Up to 90% Conversion Efficiency Typical Quiescent Current : 200A Integrated Low RDS(ON) High- and Low-Side Power MOSFET Switches: 230m and 180m Current Mode PWM Operation Fixed Frequency : 2MHz 100% Maximum Duty Cycle for Lowest Dropout Internal Soft-Start No Schottky Diode Required Over-Temperature and Over-Current Protection Small 10-Lead VDFN 3x3 Package RoHS Compliant and 100% Lead (Pb)-Free
Applications
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Ordering Information
RT8003 Package Type QV : VDFN-10L 3x3 (V-Type) Operating Temperature Range P : Pb Free with Commercial Standard
Note : RichTek Pb-free 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.
l l l l
Battery-Powered Equipments Low Power CPU and DSP Supplies Digital Cameras and Hard Disks Protable Instruments and Notebook Computers Celluar Phones, PDAs, and Handheld PCs USB-Based DSL Modems and Other Network Interface Cards
Pin Configurations
(TOP VIEW)
LX VDD NC NC EN
1 2 3 4 5 10 9
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.
GND
GND GND 8 GND 7 COMP FB
VDFN-10L 3x3
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Typical Application Circuit
VIN 2.4V to 4.2V CIN 1uF Chip Enable 5 2 VDD EN RT8003 7 6 R2 7.15k LX 1 LOUT 2.2uH VOUT 1.2V/600mA R1 10k COUT 1uF
COMP FB C COMP GND 10nF 8, 9, 10
Recommended component selection for Typical Application Circuit. VOUT (V) 0.5 1 1.2 1.8 2.5 3.3 VIN (V) 2.4 to 3.3 2.4 to 3.6 2.4 to 4.2 2.4 to 5.5 3.3 to 5.5 4.2 to 5.5 CIN (uF) 1 1 1 1 1 1 COUT (uF) 1/2.2 1/2.2 1/2.2 1/2.2 1/2.2 1/2.2 LOUT (uH) 2.2/1 2.2/1 2.2/1 2.2/1 2.2/1 2.2/1 R1 (k) 10 10 10 10 10 10 R2 (k) Open 10 7.15 3.83 2.49 1.78 CCOMP (nF) 10 10 10 10 10 10
Suggested Inductors Component Supplier ABC Sumida TDK SR0302 CDRH2D14 VLP4612 Series Inductance (H) 1 2.2 2.2 1 2.5 ESR (m) 60 90 94 110 170 Current Rating (mA) 2100 1650 1000 1500 1100 Dimensions (mm) 3x2.8x2.5 3.2x3.2x1.55 4.6x3.4x1.2
Suggested Capacitors For C IN and COUT Component Supplier TDK Panasonic TAIYO YUDEN Part No. C1608X5R1A105M C1608X5R1A225M ECJ1VB0J105M ECJ1VB0J225M JMK107BJ105M JMK107BJ225M Capacitance (uF) 1 2.2 1 2.2 1 2.2 Case Size 0603 0603 0603 0603 0603 0603
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Functional Pin Description
No 1 2 3,4 5 6 7 Pin Name Pin Function LX VDD NC EN FB COMP Internal Power MOSFET Switches Output. Connect this pin to the inductor. Power Input Supply. Input voltage which supplies current to the output pin. Connect this p in with a low-ESR capacitor to GND No Internal Connection Chip Enable (Active High). Logic low shuts down the converter. Floating this pin is forbidden. Switcher Feedback Voltage. This pin is the inverting input of the error amplifier. FB senses the switcher output through an external resistor divider network. FB regulation voltage is 0.5V. Compensation Input. This pin is the output of the internal error amplifier. Connect an external capacitor to compensate the regulator controlled loop. Ties the pin directly to the cathode terminal of C IN and COUT and ground plane with the lowest impedance. Signal and Common Ground (Exposed thermal pad is connected to GND). The GND pad area should be as large as possible and using many vias to conduct the heat into the buried GND plate of PCB layer. All small-signal, compensation and feedback components should connect to this pin.
8,9,10
GND
Function Block Diagram
EN VDD
Shutdown Control Oscillator COMP VREF
Slope Compensation
Current Limit Detector
Over Temperature Detector
Current Sense
PWM Comparator
+
Error Amplifier
+
Control Logic
Driver
LX
FB
-
Zero Detector
GND
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Absolute Maximum Ratings
l
(Note 1)
Supply Voltage ----------------------------------------------------------------------------------------------------0.3V to 6V l LX Voltage --------------------------------------------------------------------------------------------------------- -0.3V to (VDD + 0.3V) l Power Dissipation, PD @ TA = 25C VDFN-10L 3x3 ----------------------------------------------------------------------------------------------------1.923W l Package Thermal Resistance (Note 4) VDFN-10L 3x3, JA -----------------------------------------------------------------------------------------------52C/W l Junction Temperature -------------------------------------------------------------------------------------------150C l Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------260C l Storage Temperature Range ----------------------------------------------------------------------------------- -65C to 150C l ESD Susceptibility (Note 2) HBM (Human Body Mode) -------------------------------------------------------------------------------------2kV MM (Machine Mode) --------------------------------------------------------------------------------------------200V
Recommended Operating Conditions
l l l l
(Note 3)
Supply Voltage ---------------------------------------------------------------------------------------------------2.4V to 5.5V Enable Input Voltage, VEN -------------------------------------------------------------------------------------0V to 5.5V Ambient Temperature Range ---------------------------------------------------------------------------------- -40C to 85C Junction Temperature Range ----------------------------------------------------------------------------------0C to 125C
Electrical Characteristics
(VDD = 3.3V, TA = 25C, unless otherwise specified)
Parameter Supply Current Quiescent Current Shutdown Current Reference Reference Voltage Oscillator Switching Frequency Range Maximum Duty Cycle Output Voltage Line Regulation Load Regulation Power Switches RDS(ON) of P-Channel MOSFET RDS(ON) of N-Channel MOSFET Current Limit
Symbol
Test Conditions
Min
Typ
Max
Units
IQ ISHDN
VEN = 3.3V, VFB = VREF + 0.15V, IOUT = 0mA VEN = 0V
---
200 0.01
400 1
A A
VREF
0.4925
0.5
0.5075
V
fOSC DC VDD = VOUT
1.7 100
2.0 --
2.3 --
MHz %
VDD = 2.4V to 5.5V, ILOAD = 100mA 10mA < ILOAD < 600mA
---
---
+1.5 +1.5
% %
R P_FET R N_FET ILIMIT
VDD = 3.3V, ILX = 300mA VDD = 3.3V, ILX = -300mA VDD = 3.3V, VFB = VREF - 0.15V
----
230 180 1.8
----
m m A
To be continued
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Parameter Logic Input EN Threshold Protection Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSD TSD --180 20 --C C Logic-Low Voltage VIL Logic-High Voltage VIH VDD = 2.4V to 5.5V, Shutdown VDD = 2.4V to 5.5V, Enable -1.5 --0.4 -V Symbol Test Conditions Min Typ Max Units
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. JA is measured in the natural convection at TA = 25C on a high effective thermal conductivity test board of JEDEC 51-7 thermal measurement standard.
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RT8003
Typical Operating Characteristics
Output Voltage Deviation vs. Output Current
0.10% 0.1
Output Voltage Deviation vs. Temperature
0.40% 0.4
Output Voltage Deviation (%)
Output Voltage Deviation (%)
0 100 200 300 400 500 600 700 800
0.00% 0 -0.10% -0.1 -0.20% -0.2 -0.30% -0.3 -0.40% -0.4 -0.50% -0.5 -0.60% -0.6 -0.70% -0.7
0.20% 0.2 0.00% 0 -0.20% -0.2 -0.40% -0.4 -0.60% -0.6 -0.80% -0.8 -1.00% -1.0 -1.20% -1.2 -1.40% -1.4 -1.60% -1.6 -1.80% -1.8 -50 -25 0 25 50 75 100 125 150
Output Current (mA)
Temperature (C)
Efficiency vs. Output Current
100% 100 90% 90 100% 100
Efficiency vs. Temperature
90% 90 80% 80 70% 70
VIN = 3.3V, VOUT = 1.2V
80 80%
Efficiency (%)
70% 70 60% 60 50% 50 40% 40 30% 30 20% 20 10% 10 0% 0 1 10 100 1000
Efficiency (%)
60% 60 50% 50 40% 40 30% 30 20% 20 10% 10 0% 0 -50 -25 0 25 50 75 100 125 150
VIN = 3.3V, VOUT = 1.2V, IOUT = 200mA
Output Current (mA)
Temperature (C)
Frequency vs. Input Voltage
2.15 2.1 2.05 2
Frequency vs.Temperature
Frequency (MHz)
2.05 2 1.95 1.9 1.85 2.5 3 3.5 4 4.5 5 5.5
Frequency (MHz)
1.95 1.9 1.85 1.8 1.75 -50 -25 0 25 50 75 100 125
Input Voltage(V)
Temperature (C)
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RT8003
Quiescent Current vs. Input Voltage
300 250
Quiescent Current vs. Temperature
VIN = 3.3V, VFB = 0.65V
VFB = 0.65V
Quiescent Current (uA)
Quiescent Current (uA)
2.5 3 3.5 4 4.5 5 5.5
250 200 150 100 50 0
200
150
100
50
0 -50 -25 0 25 50 75 100 125
Input Voltage(V)
Temperature (C)
VREF vs. Temperature
0.52 0.515 0.51 0.52 0.515 0.51
VREF vs. Input Voltage
V REF (V)
0.505 0.5 0.495 0.49 0.485 0.48 -50 -25 0 25 50 75 100 125
V REF (V)
0.505 0.5 0.495 0.49 0.485 0.48 2.5 3 3.5 4 4.5 5 5.5
Temperature (C)
Input Voltage (V)
Current Limit vs. Input Voltage
3 2.5
Load Transient Response
VIN = 3.3V, VOUT = 1.2V IOUT = 50mA to 600mA
Current Limit (A)
2 1.5 1 0.5 0 2.5 3 3.5 4 4.5 5 5.5
Output Voltage
(50mV/Div)
Load Current
(200mA/Div)
Input Voltage (V)
Time (250s/Div)
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RT8003
Steady State
VIN = 3.3V, VOUT = 1.2V, IOUT = 0mA, COUT = 1uF
Steady State
VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA, COUT = 1uF
Output Voltage
(10mV/Div)
Output Voltage
(10mV/Div)
(1V/Div)
VLX
VLX
(1V/Div)
Time (25s/Div)
Time (250ns/Div)
Soft Start Function
Output Voltage
(500mV/Div)
(2V/Div)
VEN Input Current
(200mA/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA
Time (500s/Div)
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DS8003-03
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RT8003
Application Information
RT8003 is a pulse-width-modulated (PWM) step-down DCDC converter. Capable of delivering 600mA output current over a wide input voltage range from 2.4V to 5.5V. The RT8003 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy terminals. Chip Enable/Disable and Soft Start Four operational modes are available: PWM, PSM, LowDrop-Out and shut-down modes. Pulling EN pin lower than 0.4V shuts down the RT8003 and reduces its quiescent current to 1A. Pulling EN pin higher than 1.5V enables the RT8003 and initiates the softstart cycle. RT8003 has internal soft-start that can reduce the Inrush Current during the rising of Output Voltage. PWM Operation During normal operation, the RT8003 regulates output voltage by switching at a constant frequency transferring the power to the load in each cycle by PWM. The RT8003 uses a slope-compensated, current-mode PWM controller capable of achieving 100% duty cycle. At each rising edge of the internal oscillator, the Control Logic cell sends a PWM ON signal to the Driver cell to turn on internal PMOSFET. This allows current to ramp up through the inductor to the load, and stores energy in a magnetic field. The switch remains on until either the current-limit is tripped or the PWM comparator signals for the output in regulation. After the switch is turned off, the inductor releases the magnetic energy and forces current through the N-MOSFET synchronous rectifier to the output-filter capacitor and load. The output-filter capacitor stores charge when the inductor current is above the average output current and releases charge when the inductor current is below the average current to smooth the output voltage across the load. A Zero Detector monitors inductor current by sensing v oltage drop across the N-MOSFET synchronous rectifier when it turns on. The N-MOSFET turns off and allows the converter entering discontinuous conduction mode when the inductor current decreases to zero. The zero current detection on threshold is about 80mA.This reduces conduction loss and increase power conversion efficiency at light load condition.
DS8003-03 November 2005
PSM Operation Consequently, the converter will enter pulse-skipping mode (PSM) during extreme light load condition or when modulation index (VOUT /VIN) is extreme low. This could reduce switching loss and further increase power conversion efficiency. Over Current Protection The RT8003 continuously monitors the inductor current by sensing the voltage across the P-MOSFET when it turns on. When the inductor current is higher than current limit threshold (1.8A typical), OCP activates and forces the P-MOSFET turning off to limit inductor current cycle by cycle.But it will shut down when the VOUT trip the UV protection. Output Voltage Setting and Feedback Network The output voltage can be set from VREF to VIN by a voltage divider as: the internal VREF is 0.5V with 1.5% accuracy. In practical application, keep R1 = 10k respectively and choose appropriate R2 according to the required output voltage. Inductor Selection The output inductor is suggested as the table of suggested inductors for optimal performance. Make sure that the inductor will not saturate over the operation conditions including temperature range, input voltage range, and maximum output current. If possible, choose an inductor with rated current higher than 2A so that it will not saturate even under short circuit condition. Input Capacitor Selection The input capacitor can filter the input peak current and noise at input voltage source. The capacitor with low ESR (effective series resistance) provides the small drop voltage to stabilize the input voltage during the transient loading. For input capacitor selection, the ceramic capacitors larger than 1F is recommend. The capacitor must conform to the RMS current requirement. The maximum RMS ripple current is calculated as : IRMS = IOUT(MAX) VOUT (VIN - VOUT) VIN
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RT8003
Output Capacitor Selection The capacitor' s ESR determines the output ripple voltage and the initial voltage drop following a high slew-rate transient' s edge. Typically, if the ESR requirement is satisfied, the capacitance is adequate to filtering. The output ripple voltage can be calculated as:
VOUT = IC (ESR + 1 ) 8 x COUT x fOSC
LX VIN R4 C1 EN VDD RT8003 R1 FB C3 COMP GND C2 R2 L1 VOUT
Where f OSC = operating frequency, COUT = output capacitance and IC = IL = ripple current in the inductor. The ceramic capacitor with low ESR value provides the low output ripple and low size profile. Connect a 1F/2.2F ceramic capacitor at output terminal for good performance and place the input and output capacitors as close as possible to the device. Layout Considerations Follow the PCB layout guidelines for optimal performance of RT8003. 1. For the main current paths as indicated in bold lines in Figure 1, keep their traces short and wide. 2. Put the input capacitor as close as possible to the device pins (VDD and GND). 3. LX node is with high frequency voltage swing and should be kept small area. Keep analog components away from LX node to prevent stray capacitive noise pick-up. 4. Connect feedback network behind the output capacitors. Keep the loop area small. Place the feedback components near the RT8003. 5.Connect all analog grounds to a command node and then connect the command node to the power ground behind the output capacitors. 6. An example of 2-layer PCB layout is shown in Figure 2 to Figure 3 for reference.
Figure 1
Figure 2. Top Layer
Figure 3. Bottom Layer
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RT8003
Outline Dimension
D2
D
L
E
E2 SEE DETAIL A
1
e A A1 A3
b
2
1
2
1
DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated.
Symbol A A1 A3 b D D2 E E2 e L
Dimensions In Millimeters Min 0.800 0.000 0.175 0.180 2.950 2.300 2.950 1.500 0.500 0.350 0.450 Max 1.000 0.050 0.250 0.300 3.050 2.650 3.050 1.750
Dimensions In Inches Min 0.031 0.000 0.007 0.007 0.116 0.091 0.116 0.059 0.020 0.014 0.018 Max 0.039 0.002 0.010 0.012 0.120 0.104 0.120 0.069
V-Type 10L DFN 3x3 Package
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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November 2005
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