RT8058
1MHz, 2A, High Efficiency PWM Step-Down DC/DC Converter
General Description
The RT8058 is a current mode PWM step-down converter. The chip is ideal for fixed frequency and low ripple applications over full range of load conditions. Its input voltage range is from 2.6V to 5.5V with a constant 1MHz switching frequency that allows it to adopt tiny, low cost capacitors and inductors with 2mm or less in height making it ideal for single-cell Li-lon/polymer battery applications. The low on resistance internal MOSFET can achieve high efficiency without the need of external schottky diodes in wide operating ranges and the output voltage is adjustable from 0.6V to 5V that can provide up to 2A load current. The RT8058 operates at 100% duty cycle for low dropout operation that extends battery life in portable devices.
The RT8058 is available in a WQFN-16L 3x3 package.
Features
z0.6V Reference Allows Low Output Voltage
zLow Dropout Operation : 100% Duty Cycle
z2A Load Current
z<2μA Shutdown Current
zUp to 95% Efficiency
zNo Schottky Diode Required
z1MHZ Constant Switching Frequency
zLow RDS(ON) Internal Switches
zInternally Compensated
zInternal Soft-Start
zOver temperature Protection
zShort Circuit Protection
zSmall 16-Lead WQFN Package
zRoHS Compliant and 100% Lead (Pb)-Free
Ordering Information
RT8058 
Package Type
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Richtek 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.
Marking Information
For marking information, contact our sales representative directly or through a Richtek distributor located in your area.
Applications
zPortable Instruments
zMicroprocessors and DSP Core supplies
zCellular Telephones
zWireless and DSL Modems
zDigital Cameras
zPC Cards
Pin Configurations
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NC LX LX LX |
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16 |
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14 |
13 |
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PGND |
1 |
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12 |
PVDD |
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PGND |
2 |
PGND |
11 |
PVDD |
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PGND |
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10 |
PVDD |
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17 |
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FB |
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9 |
VDD |
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GND |
NC |
EN NC |
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WQFN-16L 3x3 |
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DS8058-05 April 2011 |
www.richtek.com |
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RT8058
Typical Application Circuit
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RT8058 |
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L1 |
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VIN |
10,11,12 |
PVDD |
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LX |
13,14,15 |
3.3µH |
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VOUT |
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2.6V to 5.5V |
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7 |
EN |
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R1 |
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1.2V/2A |
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100k |
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9 |
VDD |
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FB |
4 |
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COUT1 |
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COUT2 |
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CIN |
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R2 |
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22µF |
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22µF |
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10µF |
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GND |
PGND |
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100k |
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1, 2, 3, |
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Exposed Pad (17) |
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Functional Pin Description
Pin No. |
Pin Name |
Pin Function |
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1, 2, 3 |
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Power Ground. Connect this pin close to the (–) terminal of CIN and COUT. The |
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17 (Exposed Pad) |
PGND |
exposed pad must be soldered to a large PCB and connected to PGND for |
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maximum power dissipation. |
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4 |
FB |
Feedback Input Pin. Receives the feedback voltage from a resistive divider |
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connected across the output. |
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5 |
GND |
Signal Ground. Return the feedback resistive dividers to this ground, which in turn |
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connects to PGND at one point. |
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6, 8, 16 |
NC |
No Internal Connection. |
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7 |
EN |
Enable pin. A logical high level at this pin enables the converter, while a logical |
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low level causes the converter to shut down. |
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Signal Input Supply. Decouple this pin to GND with a capacitor. Normally VDD is |
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9 |
VDD |
equal to PVDD. Keep the voltage difference between VDD and PVDD less than |
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0.5V. |
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10, 11, 12 |
PVDD |
Power Input Supply of converter power stage. Decouple this pin to PGND with a |
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capacitor. |
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13, 14, 15 |
LX |
Internal Power MOSFET Switches Output of converter. Connect this pin to the |
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inductor. |
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Function Block Diagram
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ISEN |
PVDD |
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OSC |
Slope |
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Com |
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0.6V |
EA |
Output |
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OC |
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FB |
Clamp |
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Limit |
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Int-SS |
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Driver |
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0.3V |
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Control |
LX |
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Logic |
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OT |
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VREF |
POR |
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PGND |
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Temp-SEN |
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GND |
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VDD |
EN |
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www.richtek.com |
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DS8058-05 |
April |
2011 |
2 |
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RT8058 |
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Absolute Maximum Ratings |
(Note 1) |
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z Supply Input Voltage VDD, PVDD ------------------------------------------------------------------------------------- |
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−0.3V to 6V |
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z LX Pin Switch Voltage ---------------------------------------------------------------------------------------------------- |
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−0.3V to 6V |
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z Other I/O Pin Voltage ----------------------------------------------------------------------------------------------------- |
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−0.3V to 6V |
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z Power Dissipation, PD @ TA = 25°C |
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WQFN-6L 3x3 -------------------------------------------------------------------------------------------------------------- |
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1.471W |
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z Package Thermal Resistance (Note 2) |
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WQFN-16L 3x3, θJA ------------------------------------------------------------------------------------------------------- |
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68°C/W |
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WQFN-16L 3x3, θJC ------------------------------------------------------------------------------------------------------ |
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7°C/W |
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z Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- |
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260°C |
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z Storage Temperature Range -------------------------------------------------------------------------------------------- |
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−65°C to 150°C |
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z Junction Temperature ----------------------------------------------------------------------------------------------------- |
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150°C |
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z ESD Susceptibility (Note 3) |
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HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- |
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2kV |
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MM (Machine Mode) ------------------------------------------------------------------------------------------------------ |
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200V |
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Recommended Operating Conditions |
(Note 4) |
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z Supply Input Voltage ------------------------------------------------------------------------------------------------------ |
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2.6V to 5.5V |
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z Junction Temperature Range -------------------------------------------------------------------------------------------- |
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−40°C to 125°C |
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z Ambient Temperature Range -------------------------------------------------------------------------------------------- |
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−40°C to 85°C |
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Electrical Characteristics |
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(VDD = VPVDD = 3.6V, TA = 25°C, unless otherwise specified) |
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Parameter |
Symbol |
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Test Conditions |
Min |
Typ |
Max |
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Unit |
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Input Voltage Range |
VIN |
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2.6 |
-- |
5.5 |
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V |
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Feedback Voltage |
VFB |
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0.582 |
0.6 |
0.618 |
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V |
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DC Bias Current |
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Active, No Load |
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3.4 |
-- |
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mA |
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Active, Not Switching, VFB = 0.5V |
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340 |
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μA |
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(PVDD, VDD total) |
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Shutdown, EN = 0 |
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2 |
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μA |
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Under voltage Lockout |
UVLO |
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VDD Rising |
2.3 |
2.43 |
2.55 |
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V |
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Threshold |
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VDD Hysteresis |
-- |
150 |
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mV |
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Oscillator Frequency |
fOSC |
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Switching Frequency |
0.75 |
1.0 |
1.25 |
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MHz |
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EN High-Level Input Voltage |
VEN_H |
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1.4 |
-- |
-- |
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V |
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EN Low-Level Input Voltage |
VEN_L |
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-- |
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0.4 |
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V |
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Switch On Resistance, High |
RDS(ON)_P |
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IOUT = 200mA |
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142 |
210 |
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Ω |
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Switch On Resistance, Low |
RDS(ON)_N |
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IOUT = 200mA |
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96 |
160 |
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mΩ |
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Peak Current Limit |
ILIM |
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2.2 |
3 |
-- |
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A |
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Output Voltage Line Regulation |
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VIN = 2.6V to 5.5V |
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0.05 |
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%/V |
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Output Voltage Load Regulation |
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ILOAD = 0A |
Æ |
-- |
0.15 |
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%/A |
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2A |
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DS8058-05 April 2011 |
www.richtek.com |
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3 |
RT8058
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. θJA is measured in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test board of JEDEC 51-7 thermal measurement standard. The case point of θJC is on the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
www.richtek.com |
DS8058-05 April 2011 |
4 |
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RT8058
Typical Operating Characteristics
Efficiency vs. Output Current
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100 |
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VIN = 5V |
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90 |
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80 |
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VIN = 3.3V |
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70 |
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(%) |
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60 |
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Efficiency |
50 |
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40 |
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30 |
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20 |
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10 |
VOUT = 1.8V, L = 3.3μH, COUT = 22μFx2 |
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0 |
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0 |
500 |
1000 |
1500 |
2000 |
Efficiency vs. Output Current
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100 |
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90 |
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VIN = 5V |
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(%) |
70 |
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VIN = 3.3V |
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60 |
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Efficiency |
50 |
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40 |
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30 |
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20 |
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10 |
VOUT = 1.2V, L = 3.3μH, COUT = 22μFx2 |
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0 |
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0 |
500 |
1000 |
1500 |
2000 |
Output Current (mA) |
Output Current (mA) |
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1.2000 |
Output Voltage |
vs. Outout Current |
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0.6010 |
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1.1998 |
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0.6008 |
Output Voltage (V) |
1.1996 |
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Reference Voltage (V) |
0.6006 |
1.1994 |
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VIN = 5V |
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0.6004 |
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1.1992 |
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0.6002 |
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1.1990 |
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0.6000 |
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1.1988 |
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VIN = 3.3V |
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0.5998 |
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1.1986 |
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0.5996 |
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1.1984 |
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0.5994 |
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1.1982 |
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0.5992 |
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1.1980 |
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0.5990 |
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0 |
250 |
500 |
750 |
1000 |
1250 |
1500 |
1750 |
2000 |
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Reference Voltage vs. Input Voltage
2.7 |
3.1 |
3.5 |
3.9 |
4.3 |
4.7 |
5.1 |
5.5 |
Outout Current (mA)
Output Voltage vs. Temperature
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1.203 |
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(V) |
1.201 |
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1.199 |
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Voltage |
1.197 |
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1.195 |
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1.193 |
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Output |
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1.191 |
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1.189 |
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1.187 |
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VIN = 3.6V |
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1.185 |
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-50 |
-25 |
0 |
25 |
50 |
75 |
100 |
125 |
Temperature (°C)
Input Voltage (V)
Frequency vs. Temperature
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1100 |
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1050 |
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(kHz) |
1000 |
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Frequency |
950 |
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900 |
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850 |
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VIN = 3.6V, VOUT = 1.2V, IOUT = 0A |
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-50 |
-25 |
0 |
25 |
50 |
75 |
100 |
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Temperature (°C)
DS8058-05 April 2011 |
www.richtek.com |
|
5 |
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