IS31LT3178/IS32LT TO-200mA CONSTANT-CURRENT LED DRIVER

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1 IS3LT378/IS3LT378 -TO-mA DESCRIPTION The IS3LT378 and IS3LT378 are adjustable linear current devices with excellent temperature stability. A single resistor is all that is required to set the operating current from ma to ma. The devices can operate from an input voltage from.6v to 4V with a minimal voltage headroom of.v (Typ.) at 5mA. Designed with a low dropout voltage; the device can drive LED strings close to the supply voltage without switch capacitors or inductors. The EN Pin of the IS3LT378/IS3LT378 can function as the PWM signal input used for MCU PWM dimming. As a current sink it is ideal for LED lighting applications or current limiter for power supplies. The device is provided in a lead (Pb) free, SOT3-6 and SOP-8-EP packages. FEATURES Low-side current sink - Adjustable from ma to 5mA (SOT3-6)/mA (SOP-8-EP) with external resistor selection Wide input voltage range from -.6V to 4V with a low dropout of typical.v at 5mA Up to khz PWM input ±5% current accuracy over -4 C ~ +5 C Protection features: -.6%/K current roll off at high temp over 45 C for thermal protection Up to.77w (SOT3-6)/.3W (SOP-8-EP) power dissipation in a small package RoHS compliant (Pb-free) package AEC-Q qualified in progress (IS3LT378) QUICK START Figure : Photo of IS3LT378-STLS4/IS3LT378-STLA3 Evaluation Board Figure : Photo of IS3LT378-GRLS4/IS3LT378-GRLA3 Evaluation Board RECOMMENDED EQUIPMENT.6V~4V, A DC variable power supply HBLEDs ABSOLUTE MAXIMUM RATINGS 4V input voltage Caution: Do not exceed the conditions listed above, otherwise the board will be damaged. PROCEDURE The IS3LT378/IS3LT378 evaluation board are 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. ) Connect the ground terminal of the power supply to the (TP3) and the positive terminal to the VCC (TP). Connect the Anode of an external LED string to LED+ (TP5) and its Cathode to LED- (TP6). ) The evaluation board (IS3LT378-STLS4/ IS3LT378-STLA3-EB) supports three current levels, selected by JP, JP, JP3 see the table below. The test point REXT can be used to add an external resistor. The final resistance can be measured with an ohm meter across REXT and (TP7) pins. For jumpers (JP~JP3) Closed= and Open=. JP JP JP3 R EXT (kω) 33 6 Integrated Silicon Solution, Inc. Rev. A, 8//8

2 IS3LT378/IS3LT378 -TO-mA 3) The evaluation board (IS3LT378-GRLS4 /IS3LT378-GRLA3-EB) supports four current levels, selected by JP, JP, JP3, JP4 see the table on the right. The test point REXT can be used to add an external resistor. The final resistance can be measured with an ohm meter across REXT and (TP7) pins. For jumpers (JP~JP4) Closed= and Open=. JP JP JP3 JP4 R EXT (kω) ORDERING INFORMATION Part No. Temperature Range Package IS3LT378-STLS4-EB -4 C ~ +5 C, Industrial SOT-3-6, Lead-free IS3LT378-GRLS4-EB -4 C ~ +5 C, Industrial SOP-8-EP, Lead-free IS3LT378-STLA3-EB -4 C ~ +5 C, Automotive SOT-3-6, Lead-free IS3LT378-GRLA3-EB -4 C ~ +5 C, Automotive SOP-8-EP, Lead-free Table : Ordering Information For pricing, delivery, and ordering information, please contact ISSI s analog marketing team at analog@issi.com or (48) EVALUATION BOARD OPERATION IS3LT378/IS3LT378 evaluation board drives one string of HBLEDs. OUTPUT CURRENT SETING IS3LT378/IS3LT378 provides an easy constant current source solution for LED lighting applications. It uses an external resistor to adjust the LED current from ma to 5mA (SOT3-6)/mA (SOP-8-EP). The LED current can be determined by the external resistor R as Equation (): R V 6 ().6kΩ R 6kΩ for SOT3-6 package, and 8kΩ R 6kΩ for SOP-8-EP package. Where R is in Ω, I SET is desired LED current in Amp and V =.V (Typ.) R must be a % accuracy resistor with good temperature characteristics in order to ensure stable output current. The device limits the maximum output current to I OUT_LIMIT to protect itself from an output overcurrent condition caused by a low value. Do not leave pin floating. THERMAL PROTECTION The IS3LT378/IS3LT378 implements thermal roll off protection to reduce the LED current when the package s thermal dissipation is exceeded and prevent thermal runaway. The thermal roll off begins from 45 C, and linearly decreases following the junction temp to 85% of the set current value at T SD (7 C). In the event that the junction temperature exceeds 7 C, the device will go into shutdown mode. At this point, the IC begins to cool off and will resume operation once the junction temperature goes below 4 C. Integrated Silicon Solution, Inc. Rev. A, 8//8

3 IS3LT378/IS3LT378 -TO-mA VCC TP D C LED+ TP5 U LED- TP6 C 3 OUT 6 REXT TP4 JP JP JP3 EN TP C3 EN,4,5 R R3 R4 TP3 IS3LT378/IS3LT378(SOT3-6) TP7 Figure 3:IS3LT378/ IS3LT378 (SOT3-6) Application Schematic VCC TP D LED+ TP5 C C U OUT OUT 4 REXT TP4 LED- TP6 JP JP JP3 JP4 EN TP C3 3 EN 5~8 R R3 R4 R5 TP3 IS3LT378/IS3LT378(SOP-8-EP) TP7 Figure 4:IS3LT378/ IS3LT378 (SOP-8-EP) Application Schematic Integrated Silicon Solution, Inc. 3 Rev. A, 8//8

4 IS3LT378/IS3LT378 -TO-mA BILL OF MATERIALS Name Symbol Description Qty Supplier Part No. LED Driver U Constant-Current LED Driver ISSI IS3LT378-STLS4-TR IS3LT378-STLA3-TR Resistor R RES,R,/8W,±5%,SMD YAGEO RC85JR-7RL Resistor R RES,33K,/8W,±%,SMD YAGEO RC85FR-733KL Resistor R3 RES,6K,/8W,±%,SMD YAGEO RC85FR-76KL Resistor R4 RES,K,/8W,±%,SMD YAGEO RL85FR-7KL Capacitor C CAP,.µF,5V,±%,SMD YAGEO CC6KPX7R9BB4 Capacitor C CAP, nf,5v,±%,smd YAGEO CC6KPX7R9BB Capacitor C3 NC Jumper JP~JP3 Jumper 3 Test Terminal TP~TP7 Test terminal 7 Bill of materials, refer to Figure 3 above. Name Symbol Description Qty Supplier Part No. LED Driver U Constant-Current LED Driver ISSI IS3LT378-GRLS4-TR IS3LT378-GRLA3-TR Resistor R RES,R,/8W,±5%,SMD YAGEO RC85JR-7RL Resistor R RES,33K,/8W,±%,SMD YAGEO RC85FR-733KL Resistor R3 RES,6K,/8W,±%,SMD YAGEO RC85FR-76KL Resistor R4 RES,K,/8W,±%,SMD YAGEO RL85FR-7KL Resistor R5 RES,8.K,/8W,±%,SMD YAGEO RL85FR-78KL Capacitor C CAP,.µF,5V,±%,SMD YAGEO CC6KPX7R9BB4 Capacitor C CAP, nf,5v,±%,smd YAGEO CC6KPX7R9BB Capacitor C3 NC Jumper JP~JP4 Jumper 4 Test Terminal TP~TP7 Test terminal 7 Bill of materials, refer to Figure 4 above. Integrated Silicon Solution, Inc. 4 Rev. A, 8//8

5 IS3LT378/IS3LT378 -TO-mA Figure 5: Board Component Placement Guide - Top Layer (SOT3-6) Figure 6: Board PCB Layout - Top Layer (SOT3-6) Integrated Silicon Solution, Inc. 5 Rev. A, 8//8

6 IS3LT378/IS3LT378 -TO-mA Figure 7: Board Component Placement Guide - Bottom Layer (SOT3-6) Figure 8: Board PCB Layout - Bottom Layer (SOT3-6) Integrated Silicon Solution, Inc. 6 Rev. A, 8//8

7 IS3LT378/IS3LT378 -TO-mA Figure 9: Board Component Placement Guide - Top Layer (SOP-8-EP) Figure : Board PCB Layout - Top Layer (SOP-8-EP) Integrated Silicon Solution, Inc. 7 Rev. A, 8//8

8 IS3LT378/IS3LT378 -TO-mA Figure : Board Component Placement Guide - Bottom Layer (SOP-8-EP) Figure : Board PCB Layout - Bottom Layer (SOP-8-EP) Copyright 8 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. 8 Rev. A, 8//8

9 IS3LT378/IS3LT378 -TO-mA REVISION HISTORY Revision Detail Information Date A Initial release Integrated Silicon Solution, Inc. 9 Rev. A, 8//8