TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control SOP-8 Pin Definition: 1. VIN 8. RT 2. CS 7. LD 3. GND 6. VDD 4. Gate 5. PWMD General Description The TS19460 is an average current mode control LED driver IC operating in a constant off-time mode. It greatly improves accuracy, line and load regulation of the LED current without any need for loop compensation or highside current sensing. The output LED current accuracy is at ±5%, and it is equipped with current limit comparator for hiccup mode output short circuit protection. The TS19460 can be powered from an 8V~450V supply. A PWM dimming input is provided that accepts an external control TTL compatible signal. The output current can be programmed by an internal 250mV reference, or controlled externally through a 0~1.5V dimming input. The TS19460 is ideally suited for buck LED drivers and is requires only few external components (apart from the power stage) to produce a controlled LED current making it and ideal solution for low cost LED drivers. Features Ordering Information ● Fast average current controller ● Programmable constant off-time switching ● Linear and PWM dimming capability ● Requires few external components for operation Note: “G” denote for Halogen Free Product ● Output short circuit protection with skip mode Typical Application Circuit ● Pin –compatible with TS19450CS Part No. Package Packing TS19460CS RLG SOP-8 2.5kpcs / 13” Reel Application ● DC/DC or AC/DC LED driver applications ● RGB backlighting LED driver ● Back lighting of flat panel displays ● General purpose constant current source ● Signage and decorative LED lighting ● LED street lighting Absolute Maximum Ratings Parameter Symbol Limit Unit Input Voltage Range VIN to GND -0.5 ~ +470 V Internal Regulated Voltage VDD to GND 12 V -0.3 ~ (VDD+0.3) V mW CS, LD, PWMD, Gate, RT to GND Continuous Power Dissipation PD 650 Storage Temperature Range TA -65 to +150 o C TJ -40 to +150 o C RθJA 128 Junction Temperature Range Thermal Resistance – Junction to Ambient o C/W Note: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device 1/7 Version: C13 TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control Electrical Specifications (TA= 25oC, VIN= 12V, VLD=PWM=VDD, unless otherwise noted) Function Parameter Symbol Test Conditions Min Typ Max Units 8.0 -- -0.5 450 1.0 V mA 7.25 7.5 7.75 V 0 -- 1.0 V 0 -- 100 mV 6.45 6.7 6.95 V -- 500 -- mV 3.5 -- -- mA Input (1) DC Input Voltage Range Shut-down Mode Supply Current VINDC IINSD DC input voltage Pin PWMD to GND Internal Regulator Internally Regulated Voltage VDD Line Regulation of VDD ∆VDDLine Load Regulation of VDD ∆VDDLoad VIN=8V, IDD(EXT)=0 500pF at Gate, RT=226kΩ VIN=8~450V, IDD(EXT)=0 500pF at Gate, RT=226kΩ IDD(EXT)= 0 ~ 1mA 500pF at Gate, RT=226kΩ VIN rising Undervoltage Lockout Threshold UVLO Undervoltage Lockout Hysteresis ∆UVLO VIN falling Maximum Input Current IIN (MAX) VIN=8V Dimming PWMD Input Low Voltage VENL VIN=8V~450V -- -- 0.8 V PWMD Input High Voltage PWMD Pull-down resistance at PWMD VENH VIN=8V~450V 2.0 -- -- V REN VPWMD=5V 50 100 150 kΩ 238 -- 250 0.18 262 -- mV mV --- 150 200 --- mV mV 150 -32 ---- 280 1 48 ns µs --- 12 -- Average Current Sense Logic Current Sense Reference Voltage LD to Current Sense Ratio LD input Voltage Shutdown LD input Voltage Enable Current Sense Blanking Interval Minimum On-Time VCS Av(LD) VLD(OFF) ∆VLD(OFF) TBLANK TON(min) VLD falling VLD rising VCS= VCS + 30mV RT=1MΩ Off Time TOFF Max. Steady-State Duty Cycle DMAX 8 75 Hiccup Threshold Voltage Current Limit Delay CS to Gate VCS TDELAY VCS= VCS + 30mV 410 -- --- 470 150 mV ns Short Circuit Hiccup Time Minimum On-Time (Short Circuit) THICCUP TON(min) VCS= VDD 330 -- --- 460 430 µs ns Gate Sourcing Current ISOURCE VGATE=0V, VDD=7.5V 165 -- -- mA Gate Sinking Current Gate output Rise Time ISINK TRISE VGATE=VDD, VDD=7.5V CGATE=500pF, VDD=7.5V 165 -- -30 -50 mA ns -- 30 50 ns RT=226kΩ µs % Short Circuit Protection Gate Driver Gate Output Fall Time TFALL CGATE=500pF, VDD=7.5V Note: 1. Limited by package power dissipation, whichever is lower 2/7 Version: C13 TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control Block Diagram Pin Description Pin Function 1 VIN 2 CS 3 GND 4 GATE 5 PWMD 6 VDD Description This pin is the input of 8V~450V linear regulator This pin is the current sense pin used to sense the MOSFET current by means of an external sense resistor. Ground return for all internal circuitry. This pin must be electrically connected to the ground of the power train. This pin is the output GATE driver for an external N-CH Power MOSFET This is the PWM dimming input of the IC. When this pin is pulled to GND, the Gate Driver is turned off. When the pin is pulled high, the GATE driver operates normally. This is the power supply pin for all internal circuits. It must be bypassed with a low ESR capacitor to GND (≥0.1µF) This pin is the linear dimming input and sets the current sense threshold as long as the 7 LD voltage at the pin is less than 1.5V, The Gate output is disable when LD voltage <150mV(typ.) and recovery when LD voltage >200mV (typ.) 8 RT A resistor is connected between RT and GND to program the Gate off-time. 3/7 Version: C13 TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control Application Information The TS19460 is optimized to drive buck LED drivers using average current mode control. This method of control enables fairly accurate LED current control without the need for high side current sensing or the design of any closed loop controllers. The IC uses very few external components and enables both linear and PWM dimming of the LED current. A resistor connected to the RT pin programs the off-time. Constant off-time control average current mode is used for stability and to improve the LED current regulation over a wide range of input voltages. The current through the switching MOSFET source is averaged and used to give constant-current feedback. This current is detected from a sense resistor at the CS pin, the feedback operates in a fast open-loop mode, there is no compensation required, the output current is programmed as ILED = 0.25V / RCS When the Voltage at the LD input >1.5V, otherwise ILED = ( VLD * 0.181 ) / RCS When application to design the inductor witching ripple current in it is 40% of average peak to peak, full load current, the inductance can be calculated as follow: LOUT = ( VOUT(max) * TOFF ) / ( 0.4 * IOUT ) The duty cycle range of current control feedback is limited to duty <75%, A reduction in the LED current string voltage is greater than 75% of input voltage. Reducing the output LED voltage is below VOUT(MIN) = VIN * D(MIN), where D(MIN) = 1uS / (TOFF + 1uS), may also result in the loss of regulation of LED current. This condition will cause an increase in the LED current and can be possible to trip the short circuit protection comparator. The short circuit protection comparator trips when the voltage at CS exceeds 0.44V, the Gate off time (THICCUP = 400uS) is generated to prevent stair-casing of inductor current and potentially its saturation due to insufficient output voltage. The leading edge blanking delay is provide at CS to prevent false triggering of current feedback and short circuit protection. Input Voltage Regulator The TS19460 can be powered directly from its VIN pin and can work from 8.0V~450VDC at its VIN pin. When a voltage is applied at the VIN pin, the TS19460 maintains a constant 7.5V at the VDD pin. This voltage is used to power the IC and any external resistor dividers needed to control the IC. The VDD pin must be bypassed by a low ESR capacitor to provide a low impedance path for the high frequency current of the output GATE driver. The TS19460 can be also operated by supplying a voltage at the VDD pin greater than the internally regulated voltage. Please note that this external voltage at the VDD pin should not exceed 12V. Although the VIN pin of the TS19460 is rated up to 450V, the actual maximum voltage that can be applied is limited by the power dissipation in the IC. For example, if an SOP-8 (junction to ambient thermal resistance RθJA = 128°C/ W) TS19460 draws about IIN = 2.0mA from the VIN pin, and has a maximum allowable temperature rise of the junction temperature limited to about the maximum voltage at the VIN pin would be: VIN(MAX) = ( TJ(MAX) – TA ) / ( RθJA * IIN ) = 390V In these cases, to operate the TS19460 from higher input voltages, a Zener diode can be added in series with the VIN pin to divert some of the power loss from the TS19460 to the Zener diode. In the above example, using a 100V zener diode will allow the circuit to easily work up to 490V. 4/7 Version: C13 TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control Application Information (Continue) The input current drawn from the VIN pin is a sum of the 1.0mA current drawn by the internal circuit and the current drawn by the GATE driver (which in turn depends on the switching frequency and the GATE charge of the external IIN ≈ 1mA + QG x fS In the above equation, fS is the switching frequency and QG is the GATE charge of the external MOSFET (which can be obtained from the datasheet of the MOSFET). Oscillator The oscillator in the TS19460 is controlled by a single resistor connected at the RT pin. The equation governing the off-time of the GATE output is given by: TOFF(uS) = ( RT(KΩ) / 25 ) + 0.3 *within the range of 30kΩ ≤ RT ≤ 1MΩ Linear Dimming The Linear Dimming pin is used to control the LED current, when voltage at LD is fall below 1.5V, the internal reference voltage (250mV) to the constant current feedback become over ridden by VLD * 0.181, and the current in the inductor remain continuous, the LED current is given by ILED = ( VLD * 0.181 ) / RCS, The Gate output is disable when LD voltage <150mV(typ.) and recovery when LD voltage >200mV (typ.) The Linear Dimming input could also be used for mixed-mode dimming to expand the dimming ratio, in this kind of application condition, the pulse-width modulated signal of a measured amplitude below 1.5V should be applied at LD. PWM Dimming PWM Dimming can be achieved by driving the PWMD pin with a square wave signal. The rising and falling edges are limited by current slew rate in inductor, the first switching cycle is terminated upon reaching the level (250mV) at CS, the circuit is further reaching its steady state within 3~5 switching cycle regardless of the switching frequency. 5/7 Version: C13 TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control SOP-8 Mechanical Drawing Unit: Millimeters Marking Diagram Y = Year Code M = Month Code for Halogen Free Product (O=Jan, P=Feb, Q=Mar, R=Apl, S=May, T=Jun, U=Jul, V=Aug, W=Sep, X=Oct, Y=Nov, Z=Dec) L = Lot Code 6/7 Version: C13 TS19460 AC/DC WLED Driver with Average-Mode Constant Current Control Notice Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies. Information contained herein is intended to provide a product description only. No license, express or implied, to any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications. Customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify TSC for any damages resulting from such improper use or sale. 7/7 Version: C13