® RT8465 Constant Voltage High Power Factor PWM Boost Driver Controller for MR16 Application General Description Features The RT8465 is a constant output voltage, active high power factor, PWM Boost driver controller. It can be used as the first Boost stage followed by a constant current Buck converter with input from AC/electronic transformer in MR16/AR111 application. To achieve high power factor, the AC input voltage from AC/electronic transformer is sensed via the SIN pin. An internal power factor correction circuit follows the sensed sine waveform and modulates the external MOSFET duty cycle-by-cycle to achieve constant output voltage. z The output voltage is adjustable via an output resistive divider. By operating at 220kHz, the filter component size can be small to fit in tight MR16 space. To drive industrial grade MOSFET switches, the RT8465 gate driver can deliver up to 0.8A output current with 9V gate output voltage. z z z z z z z Wide Input Voltage Range : 8V to 32V High Power Factor Correction with Simple System Circuits Adjustable Constant Output Voltage Built-in High Power Factor Correction Circuit Typical 250μ μA Start-Up Supply Current Low Quiescent Current : 0.1μ μA SOP-8 Package RoHS Compliant and Halogen Free Applications z z MR16, AR111 Lamps PFC Controller Simplified Application Circuit L AC IN + ~ - D1 D2 VCC RT8465 R1 R2 SIN GATE M1 C2 C1 ICOMP C3 FB VCOMP R4 C4 R5 C5 R3 SENSE GND RS Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8465-01 March 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8465 Ordering Information Pin Configurations RT8465 (TOP VIEW) Package Type S : SOP-8 GND Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) Note : 8 2 7 SIN VCC 3 6 ICOMP SENSE 4 5 FB SOP-8 Richtek products are : ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` VCOMP GATE Suitable for use in SnPb or Pb-free soldering processes. Marking Information RT8465ZS : Product Number RT8465 ZSYMDNN YMDNN : Date Code Functional Pin Description Pin No. Pin Name Pin Function 1 GND Ground. 2 GATE Gate Driver for External MOSFET Switch. 3 VCC Power Supply. For good bypass, place a ceramic capacitor near the VCC pin. SENSE Inductor Current Sense Input. The inductor current is sensed by a resistor between GND and SENSE pins. The sense pin signal is used as the saw tooth signal to the PWM comparator. The comparator output will modulate the GATE turn-on duty to achieve the output voltage regulation. 5 FB Output Voltage Sense Input. The Output voltage is sensed through an external resistive divider. The sensed voltage (which is tied to amplifier negative input) is compared to an internal reference threshold at 1.2V (which is tied to amplifier positive input). 6 ICOMP Output of the Multiplier. To achieve high power factor, the voltage loop amplifier output signal is modulated with the sensed input voltage through the SIN pin by an internal multiplier. A compensation network between ICOMP and GND is needed. 7 SIN Input Power Voltage Sensing for PFC Function. An external resistor for input voltage sensing is connected to the power input. 8 VCOMP Output of the Internal Voltage Loop GM Amplifier. A compensation network between VCOMP and GND is needed. 4 Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8465-01 March 2013 RT8465 Function Block Diagram + + VCC 10V/8V Chip Enable 8V OVP + 35V S R - PWM Control Circuit GND ICOMP VCOMP 1.2V FB OSC + - PFC Control Circuit GATE Q 200k R SENSE SIN Operation The RT8465 is a floating-GND Boost PWM current mode controller with an integrated low side floating gate driver. The start up voltage of RT8465 is around 10V. Once VCC is above 10V, the RT8465 will maintain operation until VCC drops below 8V. The RT8465's main control loop consists of a 220kHz fixed frequency oscillator, an internal 1.2V feedback (FB) voltage sense threshold, and the PFC control circuit with a PWM comparator. In normal operation, the GATE turns high when the gate driver is set by the oscillator (OSC). When the feedback (FB) voltage is below the reference Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8465-01 March 2013 1.2V threshold, the VCOMP pin voltage will go high. The ICOMP signal is the result of VCOMP signal multiplied with SIN signal. Higher ICOMP voltage means longer GATE turn-on period. The GATE does not always turn off in each cycle. The GATE will be turned on again by OSC for the next switching cycle. The RT8465 provides several protections, including input voltage Under Voltage Lockout (UVLO), Over Current Protection (OCP) and VCC Over Voltage Protection (OVP). Additionally, to ensure the system reliability, the RT8465 is built with internal thermal protection function. is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8465 Absolute Maximum Ratings z z z z z z z z z z z (Note 1) VCC, SIN to GND ---------------------------------------------------------------------------------------------------------GATE to GND (Note 6) ------------------------------------------------------------------------------------------------VCOMP, ICMOP to GND -----------------------------------------------------------------------------------------------FB to GND -----------------------------------------------------------------------------------------------------------------SENSE to GND -----------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C −0.3V to 40V −0.3V to 16V −0.3V to 4V −0.3V to 2V −1V to 0.3V SOP-8 -----------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOP-8, θJA -----------------------------------------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ---------------------------------------------------------------------------------------------MM (Machine Model) ----------------------------------------------------------------------------------------------------- 0.53W Recommended Operating Conditions z z z 188°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 4) Supply Input Voltage, VCC ---------------------------------------------------------------------------------------------- 8V to 32V Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VCC = 24VDC, CLOAD = 1nF, RLOAD = 2.2Ω in series, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Input Start-Up Voltage VST -- 10 11 V Under Voltage Lockout Threshold VUVLO 7 8 -- V Under Voltage Lockout Threshold Hysteresis ΔVUVLO -- 2 -- V Input Supply Current ICC After Start-Up, VCC = 24V -- 2 5 mA Input Quiescent Current IQC Before Start-Up, VCC = 7V -- 0.1 -- μA Switching Frequency f SW VSIN = 14V 190 220 250 kHz Maximum Duty in Transient Operation D MAX(TR) VC = 3V -- -- 100 % Maximum Duty in Steady State Operation D MAX -- 97 -- % Blanking Time tBLANK 200 -- -- ns (Note 5) -- 650 -- ns Oscillator Minimum Turn-Off Time Current Sense Amplifier Current Sense Voltage VSENSE VCOMP = 1V, SIN = 15V -- −100 -- mV Sense Input Current ISENSE Sense = 100mV -- 10 -- μA Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 (Note 5) is a registered trademark of Richtek Technology Corporation. DS8465-01 March 2013 RT8465 Parameter Symbol Test Conditions Min Typ Max Unit No Load at GATE Pin -- 9.5 16 V IGATE = −20mA -- 9.1 -- IGATE = −100μA -- 9.4 -- IGATE = 20mA -- 0.75 -- IGATE = 100μA -- 0.5 -- GATE Drive Rise and Fall Time 1nF Load at GATE -- 70 100 ns GATE Drive Source and Sink Peak Current 1nF Load at GATE -- 0.5 0.8 A VSIN = 14V 50 60 70 VSIN = 28V 80 100 120 -- 1.2 -- V -- 16 -- μA 1.1 1.2 1.3 V -- 1 -- μA 32 35 38 V -- 150 -- °C -- 200 -- kΩ Gate Driver Output GATE Pin Maximum Voltage VGATE High VGATE_H Low VGATE_L GATE Voltage (Note 4) V V Multiplier SIN Pin Input Current ICOMP Threshold for PWM Switch Off VICOMP VC Output Current IVCOMP Feedback Voltage VFB Feedback Input Current IFB VFB = 1.2V VOVP VCC Pin 0.5V ≤ VC ≤ 2.4V (Note 5) (Note 5) μA OVP and Soft-Start Over Voltage Protection Thermal Protection Thermal Shutdown Temperature TSD SIN Pin Input Resistance Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and 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 may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Guaranteed by design; not subject to production test. Note 6. The GATE voltage is internally clamped and varies with operating conditions. Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8465-01 March 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8465 Typical Application Circuit Electronic transformer 12V AC input L + ~ - D1 D2 3 VCC RT8465 R1 R2 7 SIN GATE 2 M1 C2 C1 C3 6 ICOMP 8 VCOMP R4 C4 FB 5 R5 C5 Load : Const Current /Const Voltage R3 SENSE 4 GND GND 1 RS CC converters : RT8450/RT8471/RT8463 CC drivers : RT8482/RT8458D Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS8465-01 March 2013 RT8465 Typical Operating Characteristics VCC Supply Current vs. Input Voltage VCC Supply Current vs. Temperature 2.0 2.5 Supply Current (mA) Supply Current (mA) 1.9 1.8 1.7 1.6 1.5 2.0 1.5 1.0 0.5 VCC = 24V 1.4 0.0 8 13 18 23 28 33 -50 -25 0 Input Voltage (V) VCC_OVP vs. Temperature 50 75 100 125 100 125 UVLO vs. Temperature 15 38 37 13 UVLO (V) 36 VOVP (V) 25 Temperature (°C) 35 11 UVLO-H 9 34 7 33 UVLO-L 5 32 -50 -25 0 25 50 75 100 -50 125 -25 0 Temperature (°C) 25 50 75 Temperature (°C) FB Voltage vs. Temperature GATE Voltage High vs. Temperature 1.3 12 11 GATE Voltage (V) FB Voltage (V) 1.3 1.2 1.2 10 IGATE = −100μA 9 IGATE = −20mA 8 7 VCC = 24V 1.1 VCC = 24V 6 -50 -25 0 25 50 75 100 Temperature (°C) Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8465-01 March 2013 125 -50 -25 0 25 50 75 100 125 Temperature (°C) is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8465 GATE Voltage Low vs. Temperature Switching Frequency vs. Input Voltage 230 GATE Voltage (V) 0.8 Switching Frequency (kHz)1 1.0 IGATE = 20mA 0.6 0.4 IGATE = 100μA 0.2 VSIN = 2V 220 210 VSIN = 14V 200 190 VCC = 24V 0.0 180 -50 -25 0 25 50 75 100 125 8 13 18 Temperature (°C) 28 33 SIN Voltage vs. VSENSE Threshold Minimum On-Time vs. Temperature 700 350 VCOMP VCOMP VCOMP VCOMP VCOMP VCOMP VCOMP 600 330 VSENSE Threshold (mV) Minimum On-Time (ns) 23 Input Voltage (V) 310 290 270 500 400 = = = = = = = VCC = 24V 2.5V 2.2V 1.9V 1.6V 1.3V 1V 0.7V 300 200 100 VCC = 24V 0 250 -50 -25 0 25 50 75 100 0 125 5 10 20 25 30 VSENSE Threshold vs. Temperature SIN Input Current vs. Input Voltage 70 0.10 VSIN = 14V 0.05 VSENSE Threshold (V) 60 SIN Current (μA) 15 SIN Voltage (V) Temperature (°C) 50 40 30 20 -0.05 VSIN = 20V -0.10 VSIN = 10V -0.15 VSIN = 2V 10 VSIN = 5V 0.00 VCC = 24V, VCOMP = 3V 0 -0.20 8 13 18 23 28 Input Voltage (V) Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 33 -50 -25 0 25 50 75 100 125 Temperature (°C) is a registered trademark of Richtek Technology Corporation. DS8465-01 March 2013 RT8465 Application Information The RT8465 provides active power factor correction for power systems with fewer external components. The RT8465 can operate in both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) by fixed frequency PWM control. The fixed switching frequency is internally set at 220kHz. where VICOMP is the reference for the current sense, k is the multiplier gain, VCOMP is the error amplifier output voltage and VSIN is the sinusoidal reference voltage on pin 7. IAC + The IC operates with a dual control topology; the inner current loop and the outer voltage loop. The inner current loop of the IC controls the sinusoidal profile for the average input current. It uses the dependency of the PWM duty cycle on the line input voltage to determine the corresponding input current. This means the average input current follows the input voltage as long as the device operates in CCM. Under light load condition, depending on the choke inductance, the system may enter DCM. In DCM, the average current waveform will be distorted but the resultant harmonics are still low enough to meet the standard of IEC61000-3-2. VAC - IIN + VIN ~ - RSENSE Multiplier The multiplier has two inputs. The SIN pin is the divided sinusoidal voltage which makes the current sense comparator threshold voltage vary from zero to peak value. The other input is the output of error amplifier at VCOMP pin. In this way, the input average current wave will be sinusoidal as well as reflects the load status. In order to achieve high power factor and good THD achieved, the multiplier transfer character is designed to be linear over a wide dynamic range, namely, 1V to 20V for SIN and 0.8V to 1.2V for FB. The relationship between the multiplier output and inputs is described as the below equation : VICOMP = k × ( VCOMP − 0.7 ) × VSIN Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8465-01 March 2013 + C1 M1 VOUT ROUT - GATE 220kHz S SENSE + PWM Modulator 1 KS Sinusoidal Reference Multiplier ICOMP SIN The RT8465 employs average current control to achieve a better input current waveform. In Figure 1, the inductor current is sensed and filtered by a current error amplifier of which output drives a PWM modulator. In this way, the inner current loop tends to minimize the error between the average input current IIN and its reference. The converter works in CCM, so the same considerations done with regard to the peak current control can be applied. IOUT D1 L R Q R2 VCOMP R5 FB + VREF C5 Voltage Error Amplifier IIN, AVG Figure 1. Functional Block with PFC CCM Control Pulse Width Modulator The IC employs an average current control scheme in CCM to achieve the power factor correction. If the voltage loop is working and output voltage is kept constant, the duty cycle, DOFF, for a CCM PFC system is given as VIN DOFF = VOUT From the above equation, DOFF is proportional to VIN. The objective of the current loop is to regulate the average inductor current such that it is proportional to the duty cycle, DOFF, and the input voltage, VIN. Figure 2 shows the waveform for the control scheme. is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 R3 RT8465 Ramp Profile IIN Current Sense/Current Sense Comparator IIN, AVG GATE Drive t Figure 2. Average Current Controls in CCM The PWM is performed by the intersection of a ramp signal with the current error amplifier output. The PWM cycle starts with the GATE turn on for a minimum duration about 300ns typical. In case of the inductor current reaches the peak current limitation, the GATE will be turned off immediately when VSENSE is triggered. Error Amplifier The outer voltage loop of the cascaded control scheme regulates the PFC output bus voltage VOUT. The internal reference on the non-inverting input of the error amplifier is 1.2V. The error amplifier's inverting feedback FB is connected to an external resistor divider which senses the output voltage. The output of the error amplifier is one of the two inputs of the multiplier. A compensation loop is connected outside between the error amplifier output at the VCOMP pin, and ground of the GND pin. Normally, the compensation loop bandwidth is very low to realize high power factor for PFC converter. The compensation is also responsible for the soft start function which controls an increasing AC input current during start-up. The PFC switch's turn-on current is sensed through an external resistor in series with the switch. When the sensed voltage exceeds the threshold voltage (the multiplier output), the current sense comparator will become low and the external MOSFET will be turned off. This ensures a cycle-by-cycle current mode control operation. The maximum current sense reference is 1.8V. The max value usually occurs in start-up process or abnormal conditions such as short load. Under Voltage Lockout (UVLO) The RT8465 internal UVLO block monitors the VCC power supply with 2V hysteresis. The hysteresis behavior guarantees a one-short startup resistor and hold-up capacitor. The IC will then be consuming typically 150μA when start-up and the power dissipation on resistor would be less than 0.1W. After start-up, the operating current is typically 1.5mA to get a better efficiency. Over Voltage Protection (OVP) Whenever VOUT exceeds the rated value by 5%, the over voltage protection is activated. This is implemented by sensing the voltage at FB pin with respect to a reference voltage of 1.2V. This results in a lower input power to reduce the output voltage VOUT. VCC 10V 8V t IC's State OFF Start Normal Open Loop/ Up Operation Standby Normal Operation OFF Figure 4. State of Power VCC Operation FB ⎛ R3 × V ⎞ OUT ⎟ ⎜ ⎝ R2 + R3 ⎠ VCOMP R5 + 1.2V C5 Figure 3. Voltage Loop Amplifier Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 is a registered trademark of Richtek Technology Corporation. DS8465-01 March 2013 RT8465 Thermal Considerations Maximum Power Dissipation (W)1 0.6 For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. Four-Layer PCB 0.5 0.4 0.3 0.2 0.1 0.0 0 25 50 75 100 125 Ambient Temperature (°C) Figure 5. Derating Curve of Maximum Power Dissipation For recommended operating condition specifications, the maximum junction temperature is 125°C The junction to ambient thermal resistance, θJA, is layout dependent. For SOP-8 package, the thermal resistance, θJA, is 188°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : PD(MAX) = (125°C − 25°C) / (188°C/W) = 0.53W for SOP-8 package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 5 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. D1 VOUT COUT VIN CIN SIN R2 C2 D2 VCC C1 GATE PGND GND GND PGND 8 VCOMP GATE 2 7 SIN VCC 3 6 ICOMP SENSE 4 5 FB RVC CVC GND R3 C2 R4 VOUT Figure 6. PCB Layout Guide Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS8465-01 March 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 11 RT8465 Outline Dimension H A M J B F C I D Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 3.988 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.508 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.050 0.254 0.002 0.010 J 5.791 6.200 0.228 0.244 M 0.400 1.270 0.016 0.050 8-Lead SOP Plastic Package Richtek Technology Corporation 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. www.richtek.com 12 DS8465-01 March 2013