rt8470 Richtek Technology Corporation, rt8470 Datasheet
rt8470
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rt8470 Summary of contents
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... LED voltage. It operates from an input voltage 30V and employs hysteretic control with a high side current sense resistor to set the constant output current. The RT8470 includes an output switch and a high side output current sensing circuit, which uses an external resistor to set the nominal average output current. LED brightness control is achieved with PWM dimming from an analog or PWM input signal ...
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... Function Block Diagram Regulator Ramp Gen. ADJ www.richtek.com RT8470 VIN SENSE ADJ GND LX Pin Name LX Switch Output Terminal. Drain of internal N-MOSFETs. Ground. The exposed pad must be soldered to a large PCB and GND connected to GND for maximum power dissipation. ...
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... DS8470-03 March 2011 (Note 1) (Note 4) Symbol Test Conditions Measure on SENSE Pin with V SENSE Respect ADJ V SENSEHYS R DS(ON UVLO ΔV UVLO f RAMP V ADJ ADJ, L RT8470 IN − 5V Min Typ Max 95 100 105 is Floating. -- ± 350 -- -- 0. 5 400 -- -- 300 -- 1 ...
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... RT8470 Parameter Minimum Switch On Time Minimum Switch Off Time Quiescent Supply Current with Output Off Quiescent Supply Current with Output Switching Internal Propagation Delay Sense Pin Input Current Thermal Shutdown Thermal Shutdown Hysteresis Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings ...
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... L = 33μH LED 4.0% 4 2. LED -2.0% -2 -4.0% -4 -6. Input Voltage (V) Output Current Deviation vs. Input Voltage 7. 350mA 33μH LED 5. LED 3. LED -1.0% -1 -3.0% -3 -5. Input Voltage (V) RT8470 1 LED 7 LED LED 7 LED LED www.richtek.com 5 ...
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... RT8470 Output Current vs. Input Voltage 1.06 1 LED 2 LED 1.04 3 LED 4 LED 5 LED 1.02 6 LED 7 LED 1.00 0.98 = 0.1Ω 33μ 0. Input Voltage(V) Switching Frequency vs. Input Voltage 700 600 1 LED 2 LED 500 3 LED 4 LED 5 LED 400 6 LED 7 LED 300 200 100 = 0.1Ω 33μ ...
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... PWM Duty Cycle (%) Output Current vs. ADJ Voltage 800 600 400 200 0 0.2 0.5 0.8 1.1 ADJ Voltage (V) V vs. Temperature REF -50 - Temperature (°C) RT8470 80 100 80% 100 83mΩ 100mΩ 150mΩ 350mΩ 1.4 1.7 100 125 150 www.richtek.com 7 ...
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... RT8470 Ramp Frequency vs. Temperature 350 340 330 320 310 300 290 280 270 260 250 -50 - Temperature (°C) Leakage Current vs. Temperature 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -50 - Temperature (°C) Digital Dimming from ADJ Off V ADJ (2V/Div) I OUT (500mA/Div) Time (2.5μs/Div) www.richtek.com 100 ...
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... Power Off from VIN V IN (5V/Div) I OUT (500mA/Div) Time (10ms/Div) DS8470-03 March 2011 R = 0.1Ω or 100mΩ, 1LED S RT8470 www.richtek.com 9 ...
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... The RT8470 includes a UVLO feature with 400mV hysteresis. The internal MOSFET turns off when V below 4.8V (typ.). Setting Average Output Current The RT8470 output current which flows through the LEDs is set by an external resistor (R between the VIN and SENSE terminal. The relationship between output current (I ...
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... L high frequency characteristic and low ESR, which are ) + + R R SEN L DS(ON) suitable for the RT8470. For maximum stability over the entire operating temperature range, capacitors with better ( ) × dielectric are suggested. OUT L Thermal Protection A thermal protection feature is included to protect the RT8470 from excessive heat damage. When the junction temperature exceeds a threshold of 150° ...
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... A is the junction to ambient Layout Considerations For best performance of the RT8470, please abide the following layout guide 250°C/W JA The capacitor C placed as close as possible to the VIN and SENSE pins of the device respectively. The GND should be connected to a strong ground plane. ...
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... SOP (Exposed Pad) Plastic Package Dimensions In Inches Min Max 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.047 0.053 0.007 0.010 0.000 0.006 0.228 0.244 0.016 0.050 0.079 0.091 0.079 0.091 0.083 0.098 0.118 0.138 RT8470 www.richtek.com 13 ...
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... RT8470 Symbol Richtek Technology Corporation Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application ...