IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT DESCRIPTION RECOMMENDED EQUIPMENT The IS32LT3117 is designed for automotive lighting applications such as map light, dome light, tail light and daytime running lights. This device is a 4-channel, linear regulated, constant current LED driver which can sink 4 equal currents of up to 350mA per channel to drive high brightness LEDs over an input voltage range of 6V to 60V, while maintaining an output leakage current of less than 1µA. The sink current is easily programmed using a single external resistor. The current sinks of the IS32LT3117 may be connected in parallel to allow greater than 350mA of LED current, ie, all four VLEDx pins tied together for a maximum 1.4A sink available for one LED string. See limitations in the LED CURRENT SETTING section. The IS32LT3117 also features a PWM input to enable simple dimming control using a digital control signal. FEATURES 6V to 60V input supply voltage range Up to 1.4A total sink current Over temperature protections Thermal current regulation above 130°C Sink current matching 3% between channels PWM dimming and Shutdown control input Very few external components IC is AEC-Q100 qualified (pending) QUICK START 6.0V~60V, 2A DC power supply One digital voltmeter Four series-connected HB LED strings rated no less than 100mA A current probe to measure the HB LED current ABSOLUTE MAXIMUM RATINGS ≤ 60V power supply Caution: Do not exceed the conditions listed above, otherwise the board will be damaged. EVALUATION BOARD OPERATION The evaluation board is configured to operate each HBLED string (CHx) at 100mA. The operating current is set by the resistor value at IS32LT3117 pin 8. See “LED CURRENT SETTING” section of the datasheet for guidance in calculating resistor values for specific currents. PROCEDURE The IS32LT3117 evaluation board is fully assembled and tested. Follow the steps listed below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. 1) 2) Connect each HBLED string as follows: CHx: Connect an HBLED strings cathode to the CHx of CON3 and the anode to the CON2, Where x is 1, 2, 3 and 4. Unused CHx inputs should be connected to GND. Calculate the VCC, recommended value is 0.5V to 1V higher than the sum of the LED string’s total forward voltage drop. For example, if the LED string’s total forward voltage is 9V@100mA, the recommended VCC is 10V. Note: Selecting an input voltage much higher than the LED string’s total forward voltage will cause a high IS32LT3117 power dissipation which may lead to device shutdown. 3) Figure 1: Photo of IS32LT3117 Evaluation Board 4) Insert the current probe between the CHx terminal (CON3) and the cathode of the CHx LED string to measure the HBLED current JP1 is used to configure the PWM signal input mode. When JP1 is “ON” the IS32LT3117 is enabled and no external PWM signal should be connected. When JP1 is “OFF” the IS32LT3117 must be driven by an external PWM signal source. Caution: Always remove JP1 when driving the IS32LT3117 with an external PWM source. JP1 ON pulls up the TP1 pin to a possibly high VCC voltage that may damage the PWM signal source. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 03/10/2014 1 IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT 5) 6) Verify that the VCC is 10V and connect the VCC and GND to CON1. Turn on the power supply (VCC) and measure the HBLED current using the current probe and verify all currents are equal. POWER SUPPLY AND POWER DISSIPATION The dissipation is proportional to the voltage across the LED and the sink current that can be defined as: PLEDx VLEDSx I OUTx Where x is 1, 2, 3 or 4. VLEDSx is the total forward voltage of LEDs in series; IOUTx is the current of the LED series. VVLEDx is the voltage of the IS32LT3117 VLEDx pin. The power of the IS32LT3117 can be defined as: 4 P3117 (VVLEDx I OUTx ) VCC I Q x 1 4 (VCC VLEDS x ) I OUTx ) VCC I Q x 1 LED CURRENT SETTING The maximum sink current of all four channels (VLEDx) is set by resistor (RISET) connected from the IS32LT3117 ISET pin (8) to ground. The maximum possible current is 350mA per VLEDx pin, however, more than one VLEDx pin can be tied together to allow for larger currents. Two combined VLEDx pins will double the available sink current for the LED string, while combining all four VLEDx pins will result in 4x the sink current for one LED string. The VLEDx sink current can be calculated by the following; VISET=1.27V (Typ.): I SINKx 1600 V ISET R ISET From Figure 2, RISET=R1//R2, for accurate LED current, resistors should be 1% or better tolerance. More information please refers to the IS32LT3117 datasheet. HB LED Digital-Dimming Control The JP1 connector is used for configuring the dimming function as in the table below: JP1 Configuration Description Assume VCC=10V, IOUTx =0.1A, VLEDSx=9V, IQ=5mA: ON No external PWM signal PLEDx=9V×0.1A=0.9W OFF Connect external PWM signal source P3117=(10V-9V)×0.1A×4+10V×0.005A = 0.45W The voltage at VLEDx pin of the IS32LT3117 will be the remaining value of VCC-VOUTx, and if it is larger than 2V@350mA (VVLEDx, recommended max headroom voltage), the IC dissipation will be high which may trigger the IC over temperature protection (OVP). The evaluation board features a PWM input terminal for connecting an external digital PWM signal. JP1 connector is used to connect or disconnect a 100k ohm pull up resistor (R3) to the PWM input. Apply a digital PWM signal with a 0.8V logic-low (or less) and a 2.1V logic high (or greater) level, and frequencies from 4kHz to 100kHz. To adjust the HB LED brightness, vary the signal duty cycle from 0 to 100. Caution: If JP1 is “ON” the PWM pin will be pulled up to the input VCC which can be up to 60V. ORDERING INFORMATION Part No. Temperature Range Package IS32LT3117-ZLA3-EB -40°C ~ +125°C (Automotive Range) eTSSOP-16, Lead-free Table1: Ordering Information For pricing, delivery, and ordering information, please contact ISSI’s analog marketing team at [email protected] or (408) 969-6600 Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 03/10/2014 2 IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT VCC C3 VCC 33uF/100V U1 VCC 3 C1 GND 10uF/100V CON2 VCC Vref 9 C2 C4 0.1uF/10V 0.1uF/100V CON1 100K R3 VLED1 PWM 1 CH2 VLED2 8 R2 20K NC 14 CH3 Iset VLED3 6 7 2 5 CH1 PWM TP1 R1 16 AGND AGND PGND PGND VLED4 12 CH4 10 CON3 IS32LT3117-EB Figure 2: IS32LT3117 Application Schematic BILL OF MATERIALS Name Symbol LED Driver U1 Resistor Description Qty Supplier Part No. Constant current LED driver 1 ISSI IS32LT3117 R1 RES,20k,1/10W,±1%,SMD 1 YAGEO Resistor R2 NC 1 Resistor R3 RES,100k,1/10W,±5%,SMD 1 YAGEO Capacitor C1 CAP,10µF,100V,±20%,SMD 1 YAGEO Capacitor C2 CAP, 0.1µF,100V,±20%,SMD 1 YAGEO Capacitor C3 CAP,33µF,100V,±20%,SMD 1 YAGEO Jumper JP1 2.54mm Jumper 1 connectors CON1~CON3 3 Bill of materials, refer to Figure 2 above. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 3/10/2014 3 IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT Figure 3: Board Component Placement Guide -Top Layer Figure 4: Board PCB Layout- Top Layer Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 3/10/2014 4 IS32LT3117 60V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP FOR AUTOMOTIVE LIGHT Figure 5: Board Component Placement Guide -Bottom Layer Figure 6: Board PCB Layout-Bottom Layer Copyright © 2014 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 3/10/2014 5