RT8272 RICHTEK [Richtek Technology Corporation], RT8272 Datasheet
RT8272
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RT8272 Summary of contents
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... Step-Down Converter General Description The RT8272 is a high voltage buck converter that can support the input voltage range from 4.75V to 24V and the output current can 3A. Current Mode operation provides fast transient response and eases loop stabilization. ...
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... RT8272 Table 1. Recommended Component Selection V (V) R1 (kΩ) OUT 15 153 10 100 3.3 25.8 2.5 17 1.8 9.1 1.2 3 Functional Pin Description Pin No. Pin Name 1 BOOT 2 VIN GND 9 (Exposed Pad COMP www.richtek.com 2 R2 (kΩ) R (kΩ 0. ...
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... Ambient Temperature Range ------------------------------------------------------------------------------ DS8272-02 March 2011 Oscillator 1.2MHz/440kHz CC Foldback Control 0. Comparator 0.92V + 680µA/V FB COMP (Note 1) (Note 4) Current Sense Slope Comp Amplifier + - Logic + - Current Comparator − 40°C to 125°C − 40°C to 85°C RT8272 VA BOOT SW GND + 0.3V) IN − 0.3V 6V www.richtek.com 3 ...
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... RT8272 Electrical Characteristics (V = 12V 25°C unless otherwise specified Parameter Feedback Reference Voltage High Side Switch-On Resistance Low Side Switch-On Resistance Switch Leakage Current Limit Current Sense Transconductance Error Amplifier Tansconductance Oscillator Frequency Short Circuit Oscillation Frequency Maximum Duty Cycle ...
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... Input Voltage (V) Output Voltage vs. Output Current 3.350 3.345 3.340 3.335 3.330 3.325 3.320 3.315 3.310 3.305 3.300 0 0.5 1 1.5 Output Current (A) Frequency vs. Temperature 1.30 1.25 1.20 1.15 1.10 1. 12V OUT 1.00 -50 - Temperature (°C) RT8272 12V 3.3V 0.3A OUT 75 100 125 www.richtek.com 5 ...
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... RT8272 Current Limit vs. Duty Cycle 6.2 5.8 5.4 5.0 4.6 4.2 3.8 3.4 3 Duty Cycle (%) UVLO vs. Temperature 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 -50 - Temperature ( ° C) Load Transient Response V = 12V 3.3V IN OUT OUT V OUT (50mV/Div) I OUT (2A/Div) Time (100μs/Div) www.richtek.com 6 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0. 1.40 1.30 1.20 1.10 1.00 Rising 0.90 0.80 Falling 0.70 0.60 0.50 0. 100 125 V OUT (100mV/Div) ...
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... Output Ripple V OUT (5mV/Div (10V/Div (2A/Div) Time (500ns/Div) DS8272-02 March 2011 V (5V/Div) V (1V/Div 12V 3.3V IN OUT (500mA/Div OUT V = 12V 3.3V IN OUT OUT Power Off from EN Pin OUT EN OUT Time (100μs/Div) RT8272 = 12V 3.3V OUT = 3A www.richtek.com 7 ...
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... Figure 2. External Bootstrap Diode www.richtek.com 8 Soft-Start The RT8272 contains an external soft-start clamp that gradually raises the output voltage. The soft-start timming can be programed by the external capacitor between SS pin and GND. The chip provides a 10μA charge current for the external capacitor. If 0.1μF capacitor is used to set the soft-start and it’ ...
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... OUT , is determined by : OUT ⎡ ⎤ 1 Δ ≤ Δ ESR ⎢ ⎥ OUT L ⎣ ⎦ 8fC OUT increases with input voltage. Multiple best, this ringing can couple to the output IN large enough to damage the IN RT8272 www.richtek.com 9 ...
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... P D(MAX) SOP-8 (Exposed Pad) packages The maximum power dissipation depends on operating ambient temperature for fixed T resistance θ . For RT8272 packages, the Figure derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. www.richtek.com 10 1 ...
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... Input capacitor must be placed as close to the IC as possible. The output capacitor must be placed near the RT8272. SW should be connected to inductor by wide and short trace. Keep sensitive components away from this trace. Table 2. Suggested Inductors for Typical Application Circuit Component Supplier Series TDK ...
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... RT8272 Outline Dimension EXPOSED THERMAL PAD (Bottom of Package) Symbol Option 1 Option 2 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 ...