TS19378 2A Buck (Step-down) WLED Driver SOP-8EP Pin Definition: 1. EN/SS 8. COMP 2. GND 7. FB 3. VGATE 6. OVP 4. Vcc 5. SW General Description The TS19378 is a high voltage step-down converter designed for driving up to 10 series white LEDs from a 40V system input. The total LED driving current up to 2A, which is measured through an external current sense resistor. Its low 200mV feedback voltage reduces power loss and improves efficiency. The OVP pin monitors the output voltage and turns off the converter if an over-voltage condition is present due to an open circuit condition. The TS19378 includes current limit, short circuit protection and thermal shutdown protection preventing damage. TS19378 provides high power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to the duty ratio linearly from 0 up to 100%. Since this converter can accommodate an input voltage up to 40V, it is also suitable for the operation via an AC adapter. Features Application ● Input Voltage Range 8V~40V ● White LED Backlighting ● Output voltage up to 38V ● High Power LED Application ● 2A Switch Output Current ● Multiple LED Driving ● Duty ratio: 0%~100% PWM control ● LED Lighting Equipment ● 300kHz Switching Frequency ● Enable/Disable Functions ● Soft Start Time Control ● Current limit and Thermal Shutdown ● Short Circuit Protections ● Built-in Internal SW P-CH MOS Ordering Information Part No. Package Packing TS19378CS RLG SOP-8EP 2.5Kpcs / 13” Reel Note: “G” denotes Halogen Free Product. Block Diagram 1/7 Version: A13 TS19378 2A Buck (Step-down) WLED Driver Absolute Maximum Rating Parameter Symbol Limit Unit VCC VSS - 0.3 to VSS + 45 V VCC Pin Voltage Feedback Pin Voltage VFB VSS - 0.3 to 6 V EN/SS Pin Voltage VEN/SS VSS - 0.3 to 6 V OVP Pin Voltage VOVP VSS - 0.3 to VCC V COMP Pin Voltage VCOMP VSS - 0.3 to 6 V VGATE Pin Voltage VGATE VSS - 0.3 to VCC V Switch Pin Voltage VSW VSS - 0.3 to VCC + 0.3 V Power Dissipation PD Internally limited mW Storage Temperature Range TST -65 to +150 °C Operating Junction Temperature Range TOJP -40 to +125 °C Operating Supply Voltage VOP 8 to 40 V Output Voltage VOUT 38 V Thermal Resistance from Junction to case θJC 15 °C/W Thermal Resistance from Junction to ambient θJA 40 °C/W 2 Note: θJA is measured with the PCB copper area(need connect to Exposed Pad) of approximately 1.5 in (Multi-layer). Electrical Specifications (VIN=12V, TA =25oC, unless otherwise noted) Parameter Symbol Conditions Min Typ Max Units 0.19 0.20 0.21 V Feedback Voltage VFB IOUT=0.2A Quiescent Current ICCQ VFB=0.5V force driver off -- 3 6 mA Feedback Bias Current IFB IOUT=0.1A -- 0.1 0.5 uA Shutdown Supply Current ISD VEN =0V -- 150 300 uA ISWLIMIT 2.5 -- -- A Oscillation Frequency FOSC 240 300 360 KHz Short Frequency FOSC -- 50 -- KHz Low (regulator OFF) -- -- 0.8 V Switch Current Limit EN/SS Pin Shutdown Logic input threshold voltage VSL EN/SS Pin Input Current IEN/SS VEN=0V -- 5 -- uA Internal MOSFET RDSON RDSON VCC=5V, VFB=0V -- 130 180 mΩ OVP Sense Voltage VOVP 0.833 0.850 0.867 V Thermal shutdown Temp TSD -- 150 -- °C Thermal shutdown Hysteresis TSH -- 40 -- °C 2/7 Version: A13 TS19378 2A Buck (Step-down) WLED Driver Typical Application Circuit A: Normal Application Circuit VOUT VIN AX2005/A U1 4 3 C1 C2 C3 220uF 0.1uF 1uF 2 20K 1 SW VCC 33uH L1 5 7 VGATE LED-1 FB VSS 8 COMP EN/SS D1 B340 ILED R1 0.1uF 470uF 6 OVP C5 C4 R2 LED-N 100Ω R3 C6 C7 8.2K 0.1uF 15n R5 R4 0.6Ω D2 Dimming 100Hz-50KHz DIODE VFB = 0.2V ILED = VFB/R5 VOVP (OVP) = 0.85× (1+ R1 ) R4 COUT ESR Range R2 C7 30~80mΩ 470R 10nF 80~300mΩ 100R 15nF B: AC Input Application Circuit 9Inverting) Bridge rectifier U1 4 AC adapter 3 C1 C2 220uF 0.1uF C3 C4 100uF 1uF 2 20K 1 AX2005/A SW VCC FB VGATE VSS COMP EN/SS OVP 5 L1 7 33uH LED-1 D1 B340 8 LED-2 6 ILED R2 LED-3 C5 0.1uF 560Ω R3 C6 8.2K 0.1uF LED-4 C7 R1 R4 33nF R5 0.6Ω VOUT VFB = 0.2V ILED = VFB/R5 VOVP (OVP) = 0.85× (1+ R1 ) R4 ILED 350mA 750mA 1000mA R5 0.57Ω 0.266Ω 0.2Ω 70mW 150mW 200mW C1 100uF 220uF 330uF L1 33uH 3/7 Version: A13 TS19378 2A Buck (Step-down) WLED Driver Function Descriptions PWM Control The TS19378 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the TS19378, the pulse width varies in a range from 0 to 100%, according to the load current. The ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current Setting ILED Current Application circuit item shows the basic application circuit with TS19378 adjustable output version. The external resistor sets the LED output current according to the following formula: ILED=(0.25V/R5), VFB=0.2V Resistor select for LED output current setting ILED R2 350mA 0.57Ω 70mW 750mA 0.266Ω 150mW 1000mA 0.2Ω 200mW Current Liming The current limit threshold is setting by the internal circuit. Compensation In all LED driver applications. Connecting a resistor (R2) and a capacitor (C7) from COMP pin to GND. Please refer the application circuit table to design. EN/SS This pin can be supplied shutdown or soft start function. It is inside pull high function. For normal application, the pin must be connected a capacitor to ground. There is a 5uA current to charge this capacitor, vary the different capacitor value to control soft start time. Allow the switching regulator circuit to be shutdown pulling this pin below a 0.8V threshold voltage; the shutdown supply current is approximately 150uA Inductor Selection For most designs, the different frequency can be reducing the inductor value; The TS19378 is suggested 33uH. Where is inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in high ripple currents. Choose inductor ripple current approximately 20% of the maximum load current 2A, ∆IL=0.4A. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (2A+0.2A). Input Capacitor Selection This capacitor should be located close to the IC using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage. The RMS current rating requirement for the input capacitor of a buck regulator is approximately 1⁄2 the DC load current. A low ESR input capacitor sized for maximum RMS current must be used. A 220µF low ESR capacitor for most applications is sufficient. Over Voltage Protection The OVP voltage is set by outside resistance (R1 and R4). The external resistor sets the OVP voltage according to the following equation: VOUT (OVP) = VOVP × (1+ R4 ) R1 If VOVP >0.85V, The OVP is happened that to disable the driver until VOVP <0.85V. 4/7 Version: A13 TS19378 2A Buck (Step-down) WLED Driver Function Descriptions (Continue) Output Capacitor Selection For lower output voltage ripple and more stable LED current, higher value output capacitor and low ESR is recommended. A 470uF electrolytic capacitor works for most of the applications. 5/7 Version: A13 TS19378 2A Buck (Step-down) WLED Driver SOP-8EP Mechanical Drawing DIM A B C D E E1 F G K M P R SOP-8EP DIMENSION MILLIMETERS INCHES MIN MAX MIN MAX. 4.80 5.00 0.189 0.196 3.80 4.00 0.150 0.157 1.35 1.75 0.054 0.068 0.35 0.49 0.014 0.019 2.05 2.41 0.081 0.095 2.82 3.30 0.111 0.130 0.40 1.25 0.016 0.049 1.27BSC 0.05BSC 0.10 0.25 0.004 0.009 0º 7º 0º 7º 5.80 6.20 0.229 0.244 0.25 0.50 0.010 0.019 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: A13 TS19378 2A Buck (Step-down) WLED Driver 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: A13