PAM2863ECR

A Product Line of Diodes Incorporated PAM2863 2A LED DRIVER with INTERNAL SWITCH Description Pin Assignments The PAM2863 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 4.5V and 40V and provides an externally adjustable output current of up to 2A. Depending upon supply voltage and external components, this can provide up to 30 watts of output power. The PAM2863 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted below the set value, by applying an external control signal to the VSET pin. The VSET pin will accept either a DC voltage or a PWM waveform. The soft-start time can be increased using an external capacitor from the VSET pin to ground. Applying a voltage of 0.2V or lower to the VSET pin turns the output off and switches the device into a low current standby state. Features • Simple Low Parts Count • Internal 40V NDMOS Switch • 2A Output Current • Applications • High End LED Flashlight • LED Light Bar Single Pin On/Off and Brightness Control Using DC Voltage or PWM • Soft-Start • High Efficiency (up to 97%) • Wide Input Voltage Range: 4.5V to 40V • Output Shutdown • Open LED Protection • Short LED Protection • Up to 1MHz Switching Frequency • Typical 5% Output Current Accuracy • Pb-Free SOP-8(EP) Packages PAM2863 Document number: DSxxxxx Rev. 1 - 0 1 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Typical Applications Circuit Pin Descriptions Pin Number 5, 6 3, 7, 8 Pin Name LX GND 4 VSET 2 1 ISENSE VIN Function Drain of NDMOS switch. Ground (0V) • Multi-function On/Off and brightness control pin: • Leave floating for normal operation. • Drive to voltage below 0.2V to turn off output current • Drive with DC voltage (0.3V < VSET< 2.5V) to adjust output current from 12% to 100% of IOUTnom • Drive with PWM signal from open-collector or open-drain transistor, to adjust output current. Adjustment range 1% to 100% of IOUTnom for f < 500Hz • Connect a capacitor from this pin to ground to increase soft-start time. (Default soft-start time = 0.1ms. Additional soft-start time is approx.1.5ms/1nF) Connect resistor RS from this pin to VIN to define nominal average output current IOUTnom = 0.1/Rs Input voltage (6V to 40V). Decouple to ground with 10μF or higher X7R ceramic capacitor close to device. PAM2863 Document number: DSxxxxx Rev. 1 - 0 2 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Functional Block Diagram Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Parameter Input Voltage Range Rating -0.3 to +40 Unit LX, ISENSE Pin Voltage VSET Pin Voltage Maximum Junction Temperature Storage Temperature Soldering Temperature -0.3 to +40 V -0.3 to +6.0 170 -65 to +170 300, 5sec °C Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) Parameter Input Voltage Range Ambient Temperature Range Junction Temperature Range PAM2863 Document number: DSxxxxx Rev. 1 - 0 Rating 4.5 to 40 -40 to +85 -40 to +125 Unit V °C °C 3 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Thermal Information Parameter Package Symbol Max Thermal Resistance (Junction to Ambient) SOP-8(EP) θJA 90 Thermal Resistance (Junction to Case) SOP-8(EP) θJC 11 Unit °C/W Electrical Characteristics (@TA = +25°C, VIN = 16V, unless otherwise specified.) Parameter Inout Voltage Symbol Output Current ILED Shutdown Current ISD Quiescent Current without Switching Mean Current Sense Threshold Voltage Sense Threshold Hysteresis ISENSE Pin Input Current VSET Range on VSET Pin Test Conditions Min Typ 4.5 VIN 40 RS = 0.1Ω 2 VSET Pin Grounded 20 IQ VSET Pin Floating, VIN = 16V 0.6 VSENSE Measured on ISENSE Pin with Respect to VIN 95 VSENSE_HYS VSENSE = VIN -0.1 VEN For DC Dimming 100 Units V 1 RS = 0.05Ω ISENSE Max A A 40 µA mA 105 mV ±13 % 8 µA 0.3 2.5 V DC Voltage on VSET Pin to Enable VEN(ON) VEN Rising 0.25 V DC Voltage on VSET Pin to Disable VEN(OFF) VEN Falling 0.2 V @ILX = 100mA 0.3 LX Switch on Resistance LX Switch Leakage Current Soft-Start Time Operating Frequency RLX VIN = 16V, CEN = 1nF 1.5 Ms FLX VIN = 16V, VO = 9.6V (3 LEDs), L = 47µH, ΔI = 0.25A (ILED = 1A) 233 kHz For 4% Accuracy 500 TON_REC Recommended Maximum Switch Frequency FLX(MAX) Max Duty Circle Internal Comparator Propagation Delay Over Temperature Protection Temp Protection Hysteresis Current Limit Note: µA TSS Recommended Minimum Switch ON Time Recommended Duty Cycle Range Ω 5 ILX(LEAK) Ns 1.0 MHz 75 % 98 25 DLX % TPD (Note 1) 45 Ns TOTP 150 °C TOTP_HYS 40 °C 2.5 A IXL(MAX) Peak Inductor Current 1. VSENSE: LevelA: 95mV to 100mV; level B: 100mV to 105mV Parameters are not tested at production, but guaranteed by design. PAM2863 Document number: DSxxxxx Rev. 1 - 0 4 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Typical Performance Characteristics (@TA = +25°C, VIN = 16V, unless otherwise specified.) PAM2863 Document number: DSxxxxx Rev. 1 - 0 5 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Typical Performance Characteristics (cont.) (@TA = +25°C, VIN = 16V, unless otherwise specified.) PAM2863 Document number: DSxxxxx Rev. 1 - 0 6 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Typical Performance Characteristics (cont.) (@TA = +25°C, VIN = 16V, unless otherwise specified.) PAM2863 Document number: DSxxxxx Rev. 1 - 0 7 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Application Information Setting Nominal Average Output Current with External Resistor RS The nominal average output current in the LED(s) is determined by the value of the external current sense resistor (RS) connected between VIN and ISENSE and is given by: IOUT(NOM) = 0 .1 RS The table below gives values of nominal average output current for several preferred values of current setting resistor (RS) in the typical application circuit shown on page 1. Nominal Average Output Current (mA) 2000 1500 1000 760 667 333 RS (Ω) 0.05 0.067 0.1 0.13 0.15 0.3 The above values assume that the VSET pin is floating and at a nominal voltage of VREF (2.5V). Note that RS = 0.1Ω is the minimum allowed value of sense resistor under these conditions to maintain switch current below the specified maximum value. It is possible to use different values of RS if the VSET pin is driven from an external voltage. Capacitor Selection A low ESR capacitor should be used for input decoupling, as the ESR of this capacitor appears in series with the supply source impedance and lowers overall efficiency. This capacitor has to supply the relatively high peak current to the coil and smooth the current ripple on the input supply. A minimum value of 10µF is acceptable if the input source is close to the device, but higher values will improve performance at lower input voltages, especially when the source impedance is high. The input capacitor should be placed as close as possible to the IC. For maximum stability over temperature and voltage, capacitors with X7R, X5R, or better dielectric are recommended. Capacitors with Y5Vdielectric are not suitable for decoupling in this application and should NOT be used. Inductor Selection Recommended inductor values for the PAM2863 are in the range 33µH to 100µH. Higher values of inductance are recommended at higher supply voltages in order to minimize errors due to switching delays, which in increased ripple and lower efficiency. Higher values of inductance also result in a smaller change in output current over the supply voltage range. The inductor should be mounted as close to the device as possilbe with low resistance connections to the LX and VIN pins. The chosen coil should have a saturation current higher than the peak output current and a continuous current rating above the required mean output current. The inductor value should be chosen to maintain operating duty cycle and switch ‘on’/’off’ times within the specified limits over the supply voltage and load current range. The following equations can be used as a guide. LX Switch ‘On’ time TON = LΔI VIN − VLED − ILED (RS + RL + RLX ) Lx Switch ‘Off’ time TOFF = LΔI VLED + VD + ILED (RS + RL ) Where: L is the coil inductance; RL is the coil resistance; RS is the current sense resistance ILED is the required LED current; ΔI is the coil peakpeak ripple current (Internally set to 0.25 x ILED); VIN is the supply voltage; VLED is the total LED forward voltage; RLX is the switch resistance (0.3Ω nominal); VD is the diode forward voltage at the required load current PAM2863 Document number: DSxxxxx Rev. 1 - 0 8 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Ordering Information Part Number PAM2863ECR Part Marking P2863 XXXYW Package Type Standard Package SOP-8(EP) 2500 Units/ Tape&Reel Marking Information PAM2863 Document number: DSxxxxx Rev. 1 - 0 9 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 Package Outline Dimensions (All dimensions in mm.) SOP-8(EP) PAM2863 Document number: DSxxxxx Rev. 1 - 0 10 of 11 www.diodes.com October 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2863 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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Copyright © 2012, Diodes Incorporated www.diodes.com PAM2863 Document number: DSxxxxx Rev. 1 - 0 11 of 11 www.diodes.com October 2012 © Diodes Incorporated