PA5711 High Voltage LED Driver ANALOG PRODUCTS DIVISION FEATURES GENERAL DESCRIPTION The PA5711 is a High-Efficiency LED driver with multiple dimming options that include Pulse Width Modulation (PWM), Linear dimming (LD), Motion Detection (MD) and Light sense (LS) inputs. PA5711 features a direct gate driver control through an active high enable pin. It has an internal oscillator whose frequency can be set externally through a resistor. 11V to 480V Input Voltage Range. Over 95% Efficiency. Drives from 1 to hundreds of LED’s in Serial and Parallel combinations. Constant LED Drive current. Linear or PWM luminance dimming control. Light sense and Motion detection inputs to control the LED’s. Resistor Programmable Oscillator Frequency. QFN-16 RoHs Compliant Package. The PA5711 allows the users to introduce the leading edge blanking upon their desired delay requirements, also this can be used to control the Duty cycle of the driver. APPLICATIONS The PA5711 in fly-back mode can be used as a current controlled LED driver (Isolated), driving an LED load at fixed current from a few mA to over 1.4A. The LD pin allows the users to set the threshold beneath the pre-set 280mV, for smaller duty cycle and reduced dissipation across the CS resistors. General Illumination Displays Industrial and Decorative LED Lighting. Automotive applications. DC/DC or AC/DC LED driver applications. Constant current source. SMPS switching controller. LED back lighting. Security, Street and Parking garage lighting. The PA5711 has a PWM dimming option that through an externally programmed control signal, with duty ratio 0-100% and a frequency of a few Kilo-hertz, can control the LED brightness. PA5711 BLOCK DIAGRAM VIN ROSC REXT Voltage Regulator Oscillator VDD 280mV + Gate PWM Controller Gate Driver + - CS LD GND MD PWM ORDERING INFORMATION Temperature Range -40 to 85 °C Rev.0. 03/12 LS EN Figure 1. Block diagram Package Part Number QFN-16 PA5711-T7 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 1 PA5711 High Voltage LED Driver ANALOG PRODUCTS DIVISION 1. SPECIFICATIONS 1.1 Absolute Maximum Rating Parameter Input Voltage Input and Output voltage to GND VDD, externally applied Power Dissipation Maximum Junction Temperature Operating Temperature Junction temperature (operating) Thermal Resistance Junction to Ambient Storage Temperature Symbol VIN CS, LD, PWM, MD, EN, Gate VDD-EXT PD TJMAX TA TJ ja TSTG Max -0.5 to 500 -0.3 to VDD+0.3 8 3.45 168 -40 to +85 -40 to+150 12 -55 to +150 Unit V V V W °C °C °C °C/W °C Note: Continuous operation at or beyond these conditions may permanently damage the device. 3 NC No Connect 4 VIN Supply voltage 11V- 480V 5 REXT Pin for current limiting resistor between VIN and REXT. 6 ROSC Resistor to ground sets the oscillator Frequency. 7 MD 8 LS 9 EN 10 PWM PWM input to control the Gate output. Connect to VDD when unused 11 VDD 5V regulated supply voltage output. Requires a storage capacitor to ground. External Voltage source can be connected to power the chip 12 LD Linear Dimming. Used to reduce the threshold voltage lower than the internal 280mV. Connect to VDD when unused 13 CS LED Current sense input. 14 GND Chip Ground 15 Gate Gate driver Output 16 VDD 5V regulated supply voltage output Motion detection signal input; Connect to VDD when unused. Light sense signal input; Connect to GND when unused. Gate driver enable. Connect to VDD to enable the Gate driver output. CS No Connect 15 14 13 NC 1 NC 2 NC 3 10 VIN 4 9 12 LD 8 5 6 7 Top view of the PA5711 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 11 VDD PA5711 LS No Connect NC GND NC 2 16 MD 1 Rev.0. 03/12 FUNCTION ROSC NAME REXT PIN # Gate 1.2 Pin Description VDD 1.3 Pin Configuration 2 PWM EN PA5711 High Voltage LED Driver ANALOG PRODUCTS DIVISION 1.4 Electrical Specifications Parameter Symbol Input DC Voltage Range VINDC Min Typical* 11 Shut-Down Mode Supply Current IINsd 1.3 Internal DC Voltage Regulator VDD 5 Maximum Voltage to VDD Pin VDDmax IDD(ext) VDD Current Available for External Circuitry PWM Pull-Down Resistance Current Sense Threshold Voltage 480 V 1.87 mA V DC input Voltage into the VIN pin EN to GND VDD=5 ROSC = 1M VIN=15~450V, IDD(ext)=0, Gate output open 7 V External voltage applied to VDD pin 1.0 mA Limited by package power dissipation 70 72 kΩ VPWM = 5V 280 304 mV T=25 C VDD V IOUT=10mA VIN =20V IOUT=-10mA VIN =20V 272 VGATE(high) VDD-0.2 GATE Low Output Voltage VGATE(low) fOSC 0.2 V 196 0 200 204 kHz 32 34 35 ROSC = 1 MΩ External voltage provided to PWM D 0 100 % VLD 0 250 mV Delay from CS Trip to gate low 24.8 nS tDELAY 22.9 GATE Output Rise Time tRISE 25 nS GATE Output Fall Time tFALL 20 nS Pin LS input low IQ 1.4 VLS(lo) Pin LS input high VLS(hi) Pin EN input low VEN(lo) Pin EN input high VEN(hi) Pin MD input low VMD(lo) Pin MD input high VMD(hi) Pin PWM input low VPWM(lo) Pin PWM input high VPWM(hi) 1.5 External voltage provided to the LD pin. 1.6 mA No load, VDD=5 635 mV VDD=5 mV VDD=5 mV VDD=5 mV VDD=5 mV VDD=5 mV VDD=5 mV VDD=5 mV VDD=5 630 2.28 2.85 2.38 2.55 2.24 2.66 ROSC = 150 kΩ kHz Linear Dimming Voltage Range Quiescent current Conditions 55 VCS(high) Oscillator PWM Duty Cycle Units REN GATE High Output Voltage Oscillator Frequency Max *Typical values should not be used for specification limits. TA=25°C unless otherwise specified Rev.0. 03/12 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 3 PA5711 High Voltage LED Driver ANALOG PRODUCTS DIVISION 2. FUNCTIONAL DESCRIPTION 11 to 480 V 500450V VIN ROSC REXT Voltage Regulator Oscillator VDD 280mV + PWM Controller Gate Driver Gate + - CS RCS LD GND PWM MD LS EN Figure 2. A typical Application Circuit 2.1 Overview The PA5711 is a high efficiency, low cost, off-line LED driver with multiple inputs for controlling the LED under various environmental conditions. The PA5711 driver utilizes a high voltage process for a broad input voltage range. This flexibility allows for wide range of operation from 11V to 480V DC. This enables the PA5711 to drive the applications such as decorative lighting, signage and RGB back lighting. The PA5711 in the buck topology (as shown above in Fig.2) is a common choice to use the controller in non isolated LED lighting. The PA5711 can drive multiple LED’s in a string or in parallel. This set up provides a good efficiency and constant current drive with minimal external components. The LED’s can be dimmed using voltage 0-250mV on the LD pin or by a low frequency on the PWM. To save energy by turning the LED’s off, the LED’s can also be controlled via external signals to MD, LS, and EN pins. The sense resistor at CS controls the peak current thru the LED string. Rev.0. 03/12 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 4 PA5711 High Voltage LED Driver ANALOG PRODUCTS DIVISION 2.2 LED DRIVER - THEORY OF OPERATION 2.2.2 Current Sense Resistor The gates of PWM, EN, MD, and LD are enabled when they are connected to the VDD pin. The LS must be connected to GND. In such a configuration the LED current is solely controlled by the CS resistor. Each positive edge of the oscillator turns the Gate driver output high, turning on the external MOSFET. This ramps the Inductor current and increases the voltage drop across the CS resistor. When this drop exceeds VCS, the gate driver output is low. This turns off the MOSFET decaying the inductor current until the next positive edge of the clock cycle. The current threshold limit is set by comparing the voltage developed across RCS to VCS, which is 280mV for the PA5711.This default threshold level can be reduced applying a voltage lower than VCS at the LD pin. The lower of these two thresholds limits the peak current in the inductor. The peak LED current is set by the external sense resistor connected from the CS pin to ground. The value of this resistor is determined by the average LED current, the inductor ripple current and the internal threshold voltage. The inductor is selected to keep the inductor ripple current less than 30% of the average LED current.The dissipation across this resistor is given by the formula : P = RCS* ILED 2 It is a safe practice to select the resistor with atleast twice the power rating that is calculated. Gate Driver Output 2.2.1 Voltage Regulator The PA5711 has an internal voltage regulator that can regulate 11V to 480V input voltage, with an appropriate current limiting resistor at REXT, down to 5V. The VDD pin needs to have a holding cap of 22µF to provide filtering against bounces and a 0.1µF to by pass any high frequency switching noise. The PA5711 VDD pin can supply 1mA for external circuitry. Voltage across RCS The internal voltage regulator can be bypassed by providing a voltage higher than internal VDD. This feature reduces the power dissipation and can be implemented in an application where an auxiliary supply can power to the PA5711. 2.2.3 Current Sense Blanking The total input current from the VIN supply is a sum of the quiescent current of the PA5711, which is about 1.87mA and the gate driver current. The gate driver current is dependent on the gate charge of the external MOSFET and switching frequency. The PA5711 has no internal current sense blanking circuit. This allows the user to choose and introduce the right time delay that fits the application. The user can add a RC delay network on the CS path i.e. between the RCS and the CS pin. A time delay approximation can be made using : This input current approximation can be done by using the following equation: Figure 3. PA5711 Waveforms = 5*R*C Where R and C are the delay elements IIN ≈ 1.87mA + (QGATE * fs) Where QGATE is the total gate charge of the External MOSFET. REXT in k 10 VIN Range in volts 11 - 50 20 100 330 560 750 30 - 100 75 - 200 175 - 300 290 - 400 400 - 480 2.2.4 Enable / Disable The Enable pin (EN) of the PA5711 is active high. If this pin is grounded then the Driver is disabled and chip will consume minimal current. The Gate driver is disabled and the LED’s cannot be driven during this period. For normal operation the Enable pin must be connected high. An indicative table to choose the approximate value of REXT depending on VIN Rev.0. 03/12 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 5 PA5711 ANALOG PRODUCTS DIVISION High Voltage LED Driver 2.2.5 Linear Dimming input is driven low the LED’s are turned off. The PA5711 comes with a linear dimming function which is one of the four different ways the LED can be controlled. While VCS is the maximum threshold against which the current sense resistor voltage drop is compared against, the LD pin can be used to reduce this threshold. An external resistive divider setup will allow the user to adjust the LED light intensity. 2.2.7 Light sense The PA5711 has a Light sense input to accept signal from an external light sensor. The LED’s are turned on/off dependent on the signal from the Light sensors. This pin must be connected to ground if not used. 2.2.8 Motion Detection The RCS voltage drop is compared against the lower of these two voltages. Hence decreasing the voltage provided at LD below 250mV would reduce the intensity of the LED light. This allows the user to choose from available resistors rather than calculating the resistor value in accordance with the internal threshold. The PA5711 has a motion detection input. An external motion detector can drive this pin to turn the LED’s on/off. This pin needs to be connected to VDD when not used. Since a voltage lower than the internal threshold can enable linear dimming it is advisable to connect LD to V DD when linear dimming is not required. The PA5711 can drive external MOSFETs with a gate capacitance of up to 600pF. A soft start function can be implemented on the PA5711 by using RC network to slowly ramp the voltage applied to the LD pin from GND potential to over 300mV, at which the VCS overrides the Linear Dimming Function. VDD R1 LD R2 C 2.2.9 Gate Driver 2.2.10 Oscillator The PA5711 operates at a constant frequency. The external resistor Rosc determines the oscillator frequency. The inductor size, total chip power dissipation and filter capacitors are the basis on which the switching frequency is decided. The internal oscillator has a 20% frequency accuracy. In a non-isolated mode the driver switching frequency is between 30 kHz and 200kHz. This large operating range gives the designer a reasonable compromise between switching frequency and inductor size. Figure 4. Soft-Start RC arrangement The LD pin can also be used as a feed back to the chip, especially in an isolated driver application, a feedback from the isolated portion can be applied to the LD pin to achieve greater control over the calculate current drive. 2.2.6 PWM dimming Pulse Width Modulation dimming or PWM dimming can be implemented on the PA5711 by using a low frequency Square wave signal to drive the PWM pin. The square wave frequency can be in the range of a few hundred hertz. In this setup the PWM wave will be directly driving the output of the Gate driver. PWM signals can be generated using a Microcontroller or Pulse generators. The duty cycle of the input PWM is directly proportional to the intensity of LED light. If the PWM Rev.0. 03/12 Figure 5. Frequency variation across ROSC 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 6 PA5711 ANALOG PRODUCTS DIVISION High Voltage LED Driver 2.2.11 Inductor design The LED ripple current along with factors such as Maximum TON, Minimum input voltage and total forward voltage drop across the LED’s (VF) at the desired average LED current decide the value of the inductor. The minimum voltage is dependent on the specific application and the Maximum TON is determined by the duty cycle and the switching frequency. The maximum duty cycle - Dmax is given by : Where VLEDstring Dmax = VLEDstring is the desired forward voltage drop across LED string at the designed LED current Vin Vin is the minimum input voltage The maximum duty cycle must be maintained below 50% to maintain open loop stability and sub harmonic oscillations. The Maximum ON-time can be calculated as follows: Dmax Where fs is the switching frequency tONmax = fs The size of the inductor can be calculated using the equation : tONmax * (Vin – VLEDstring) Where γ is the inductor ripple Lmin = ILED * γ The peak inductor current is given by : γ ILmax = ILED * [1+ ] 2 Rev.0. 03/12 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 7 PA5711 High Voltage LED Driver ANALOG PRODUCTS DIVISION 3. QFN-16 PACKAGE DIMENSIONS AND LAYOUT QFN-16 Dimensions Min A B A B C D E F G H J D C E J G F Typical Max mm in mm in mm in 0.70 3.925 3.925 2.25 2.25 0.028 0.155 0.155 0.089 0.089 0.014 0.25 0.010 0.030 0.157 0.157 0.091 0.091 0.026 0.022 0.008 0.012 0.8 4.075 4.075 2.35 2.35 0.35 0.75 4.00 4.00 2.30 2.30 0.65 0.55 0.20 0.30 0.031 0.160 0.160 0.093 0.093 0.000 0.030 0.000 0.014 0.75 0.35 H Min c b a b c d e f a d f mm 4.30 2.85 2.10 0.67 0.25 in 0.169 0.112 0.083 0.026 0.010 QFN-16 Pad Layout Typical mm in 4.35 0.171 2.90 0.114 2.15 0.085 0.72 0.028 0.30 0.012 0.65 0.026 Max mm 4.40 2.95 2.20 0.77 0.35 e Tape and Reel Specifications Reel Dia A0 B0 K0 D E F W P0 P2 P t-max 178 (7”) 4.1±0.05 4.1±0.05 0.80±0.05 1.50±0.10 1.75±0.10 3.50±0.05 12.00±0.30 4.00±0.10 2.00±0.05 4.00±0.10 0.25 P0 P2 D t 10 Pitches Cumulative Tolerance on Tape± 0.2 E Pin 1 indicated by Dot Top cover tape A0 F W 711 B0 711 711 K0 P Rev.0. 03/12 2929 South Fair Lane, Tempe Tel: (602) 431-8101. Fax: (602) 431-2288 www.protekdevices.com NOT FOR USE IN LIFE SUPPORT SYSTEMS 8 in 0.173 0.116 0.0866 0.030 0.014