RT8289 RICHTEK | Alldatasheet

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Technical content

Features

zzzzz High Output Current up to 5A zzzzz Internal Soft-Start zzzzz 100mΩΩΩΩΩ Internal Power MOSFET Switch zzzzz Internal Compensation Minimizes External Parts Count zzzzz High Efficiency up to 90% zzzzz 25μμμμμA Shutdown Current zzzzz Fixed 500kHz Frequency zzzzz Thermal Shutdown Protection zzzzz Cycle-by-Cycle Over Current Protection zzzzz Wide 5.5V to 32V Operating Input Range zzzzz Adjustable Output Voltage from 1.222V to 26V zzzzz Available in an SOP-8 (Exposed Pad) Package zzzzz RoHS Compliant and Halogen Free 5V/5A VIN EN GND BOOT FB SW L 10µH10nF 47µFx2 10k 3.16k VOUT4.7µF x 2 Chip Enable VIN 5.5V to 32V RT8289 D B550C 6, Exposed Pad (9) CBOOT COUT CIN Open = Automatic Startup (POSCAP) Package Type SP : SOP-8 (Exposed Pad-Option 1) RT8289 Lead Plating System G : Green (Halogen Free and Pb Free)

DS8289-01 March 2011www.richtek.com Functional Pin Description Function Block Diagram Pin No. Pin Name Pin Function

1 BOOT

High Side Gate Drive Bootstrap Input. BOOT supplies the drive for the high side N-MOSFET switch. Connect a 10nF or greater capacitor from SW to BOOT to power the high side switch. 2, 3 NC No Internal Connection. 4 FB Feedback Input. FB senses the output voltage to regulate said voltage. Drive FB with a resistive voltage divider from the output voltage. The value of the divider resistors also sets loop bandwidth. The feedback threshold is 1.222V. 5 EN Chip Enable (Active High). EN is a digital input that turns the regulator on or off. Drive EN higher than 1.4V to turn on the regulator, lower than 0.4V to turn it off. For automatic startup, leave EN unconnected. 9 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation.

7 VIN

Power Input. VIN supplies the power to the IC, as well as the step-down converter switches. Drive V IN with a 5.5V to 32V power source. Bypass V IN to GND with a suitably large capacitor to eliminate noise on the input to the IC. 8 SW Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BOOT to power the high side switch. S Q R Driver Bootstrap Control Current Sense Amplifier PWM Comparator Oscillator 500kHz Ramp Generator Regulator Reference 12k Error Amplifier 30pF400k 13pF SW BOOT FB EN VIN GND OC Limit Clamp

DS8289-01 March 2011 www.richtek.com

Electrical Characteristics

Parameter Symbol Test Conditions Min Typ Max Unit Feedback Reference Voltage V FB 5.5V ≦ VIN ≦ 32V 1.202 1.222 1.239 V High Side Switch-On Resistance R DS(ON)1 -- 100 -- m Ω Low Side Switch-On Resistance R DS(ON)2 -- 10 -- Ω Upper Switch Leakage V EN = 0V, VSW = 0V -- 0 10 μA Current Limit I LIM Duty = 90%; V BOOT−SW = 4.8V -- 6.8 -- A Current Sense Transconductance G CS Output Current to V COMP -- 5.5 -- A/V Oscillator Frequency f SW -- 500 -- kHz Short Circuit Oscillation Frequency V FB = 0V -- 120 -- kHz Maximum Duty Cycle D MAX V FB = 1V -- 90 -- % Minimum On-Time t ON -- 100 -- ns Under Voltage Lockout Threshold Rising -- 4.2 -- V Under Voltage Lockout Threshold Hy steresis -- 200 -- mV Logic Low Voltage V IL -- -- 0.4 En Threshold Logic High Voltage V IH 1.4 -- 5.5 V Enable Pull Up Current -- 1 -- μA (VIN = 12V, TA = 25°C unless otherwise specified) Absolute Maximum Ratings (Note 1) z Power Dissipation, PD @ TA = 25°C z Package Thermal Resistance (Note 3) z ESD Susceptibility (Note 4) Recommended Operating Conditions (Note 5) To be continued

DS8289-01 March 2011www.richtek.com 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. The low side MOSFET body diode forward current must be lower than 1mA Note 3. θ JA is measured in the natural convection at T A = 25°C on a high effective four layers thermal conductivity test board of JEDEC 51-7 thermal measurement standard. The measurement case position of θJC is on the exposed pad of the package. Note 4. Devices are ESD sensitive. Handling precaution is recommended. Note 5. The device is not guaranteed to function outside its operating conditions. Parameter Symbol Test Conditions Min Typ Max Unit Shutdown Current I SHDN V EN = 0V -- 25 -- μA Quiescent Current I Q V EN = 2V , VFB = 1.5V -- 0.8 1 mA Soft-Start Period -- 4 -- ms Thermal Shutdown T SD -- 150 -- °C

DS8289-01 March 2011 www.richtek.com Frequency vs. Input Voltage 450 460 470 480 490 500 510 520 530 540 550 4 8 12 16 20 24 28 32 Input Voltage (V) Frequency (kHz) 1 Frequency vs. Temperature 450 460 470 480 490 500 510 520 530 540 550 -50 -25 0 25 50 75 100 125 Temperature (°C) Frequency (kHz) 1 Reference Voltage vs. Temperature 1.210 1.212 1.214 1.216 1.218 1.220 1.222 1.224 1.226 1.228 1.230 -50 -25 0 25 50 75 100 125 Temperature (°C) Reference Voltage (V) Reference Voltage vs. Input Voltage 1.210 1.212 1.214 1.216 1.218 1.220 1.222 1.224 1.226 1.228 1.230 4 8 12 16 20 24 28 32 Input Voltage (V) Reference Voltage (V) Output Voltage vs. Output Current 4.980 4.984 4.988 4.992 4.996 5.000 5.004 5.008 012345 Output Current (A) Output Voltage (V) Efficiency vs. Output Current 100 012345 Output Current (A) Efficiency (%) Typical Operating Characteristics IOUT = 0A VOUT = 5V, IOUT = 0A VIN = 8V VIN = 12V VIN = 24V VIN = 32V VOUT = 5V VIN = 32V VIN = 24V VIN = 12V VOUT = 5V IOUT = 0A VIN = 8V VIN = 12V VIN = 24V VIN = 32V VIN = 8V VIN = 12V VIN = 24V VIN = 32V VOUT = 5V, IOUT = 0A

DS8289-01 March 2011www.richtek.com Quiescent Current vs. Temperature 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -50 -25 0 25 50 75 100 125 Temperature (°C) Quiescent Current (mA ) Shutdown Current vs. Input Voltage 4 8 12 16 20 24 28 32 Input Voltage (V) Shutdown Current (μA) 1 VEN = 0V Current Limit vs. Temperature -50 -25 0 25 50 75 100 125 Temperature (°C) Current Limit (A) Switching Time (1 μs/Div) IL (5A/Div) VSW (20V/Div) VOUT (10mV/Div) VIN = 12V, VOUT = 5V, IOUT = 5A Time (100 μs/Div) Load Transient Response VOUT (200mV/Div) IOUT (2A/Div) VIN = 12V, VOUT = 5V, IOUT = 0.2A to 5A Load Transient Response Time (100 μs/Div) IOUT (2A/Div) VOUT (200mV/Div) VIN = 12V, VOUT = 5V, IOUT = 2.5A to 5A VIN = 8V VIN = 12V VIN = 24V VIN = 32V VIN = 12V, VOUT = 2.5V

DS8289-01 March 2011 www.richtek.com Power Off from EN Time (2.5ms/Div) VIN = 12V, VOUT = 5V, IOUT = 5A VEN (5V/Div) VOUT (5V/Div) IL (5A/Div) Power On from EN Time (2.5ms/Div) VEN (5V/Div) VOUT (5V/Div) IL (5A/Div) VIN = 12V, VOUT = 5V, IOUT = 5A

deviations do not offer much relief. meet size or height requirements in the design. capacitor, please refer to table 3 for more detail. for COUT selection to ensure that the control loop is stable. response as described in a later section. capacitors are all available in surface mount packages. Special polymer capacitors offer very low ESR value. pass the surge test for use in switching power supplies. trapezoidal current at the source of the high side MOSFET. Table 2. Suggested Inductors for Typical

Figure 3. Reference Circuit with Snubber and Enable Timing Control ringing that would indicate a stability problem. guide, please refer to the section of Layout Consideration. the junction to ambient thermal resistance.

Figure 6. PCB Layout Guide Table 3. Suggested Capacitors for CIN and COUT Table 4. Suggested Diode

9 CIN

components away from this trace.

DS8289-01 March 2011 www.richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the ri ght to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property inf ringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications i s assumed by Richtek. Richtek Technology Corporation Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Richtek Technology Corporation Taipei Office (Marketing) 5F, No. 95, Minchiuan Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)86672399 Fax: (8862)86672377 Email: marketing@richtek.com Outline Dimension A BJ F H M C D I Y X EXPOSED THERMAL PAD (Bottom of Package) 8-Lead SOP (Exposed Pad) Plastic Package Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 4.000 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.510 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.000 0.152 0.000 0.006 J 5.791 6.200 0.228 0.244 M 0.406 1.270 0.016 0.050 X 2.000 2.300 0.079 0.091 Option 1 Y 2.000 2.300 0.079 0.091 X 2.100 2.500 0.083 0.098 Option 2 Y 3.000 3.500 0.118 0.138