IS32LT3170/71 10-TO-150MA CONSTANT-CURRENT LED DRIVER FOR AUTOMOTIVE Preliminary Information August 2015 GENERAL DESCRIPTION FEATURES The IS32LT3170 and IS32LT3171 are adjustable linear current devices with excellent temperature stability. A single resistor is all that is required to set the operating current from 10mA to 150mA. The devices can operate from an input voltage from 2.5V to 42V with a minimal voltage headroom of 0.6V. Designed with a low dropout voltage; the device can drive LED strings close to the supply voltage without switch capacitors or inductors. The IS32LT3170/71 simplifies designs by providing a stable current without the additional requirement of input or output capacitors, inductors, FETs or diodes. The complete constant current driver requires only a current set resistor and a small PCB area making designs both efficient and cost effective. The EN Pin (1) of the IS32LT3171 can function as the PWM signal input used for LED dimming purposes. As a current sink it is ideal for LED lighting applications or current limiter for power supplies. APPLICATIONS The device is provided in a lead (Pb) free, SOT23-6 package. Low-side current sink - Current preset to 10mA - Adjustable from 10mA to 150mA with external resistor selection Wide input voltage range from - 2.5V to 42V (IS32LT3171) - 5V to 42V (IS32LT3170) with a low dropout of 0.6V Up to 10kHz PWM input (IS32LT3171 only) Protection features: - 0.26%/K negative temperature coefficient at high temp for thermal protection Up to 1W power dissipation in a small SOT23-6 package RoHS compliant (Pb-free) package Automotive AEC-Q100 qualified (pending) Automotive and avionic lighting Architectural LED lighting Channel letters for advertising, LED strips for decorative lighting Retail lighting in fridge, freezer case and vending machines Emergency lighting (e.g. steps lighting, exit way sign etc.) TYPICAL APPLICATION CIRCUIT Figure 1 Typical Application Circuit Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 1 IS32LT3170/71 PIN CONFIGURATION Package Pin Configuration (Top View) SOT23-6 PIN DESCRIPTION No. Pin Description 1 EN Enable pin (PWM input IS32LT3171 only). 2,3,5 OUT Current sink. 4 GND Ground. 6 REXT Optional current adjust. Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 2 IS32LT3170/71 ORDERING INFORMATION Automotive Range: -40°C to +125°C Order Part No. Package QTY/Reel IS32LT3170-STLA3-TR IS32LT3171-STLA3-TR SOT-23-6, Lead-free 3000 Copyright © 2015 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. 0A, 08/04/2015 3 IS32LT3170/71 ABSOLUTE MAXIMUM RATINGS (Note 1) Maximum enable voltage, VEN(MAX) only for IS32LT3170-STLA3-TR VEN(MAX) only for IS32LT3171-STLA3-TR Maximum output current, IOUT(MAX) Maximum output voltage, VOUT(MAX) Reverse voltage between all terminals, VR Junction to ambient, θJA Power dissipation, PD(MAX) (Note 2) Maximum junction temperature, TJMAX Storage temperature range, TSTG Operating temperature range, TA ESD (HBM) ESD (CDM) 45V 6V 200mA 45V 0.5V 94.8°C/W 1W 150°C -65°C ~ +150°C −40°C ~ +125°C 2kV 500V Note 1: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note 2: Detail information please refer to package thermal de-rating curve on Page 13. ELECTRICAL CHARACTERISTICS “●” This symbol in the table means these parameters are for IS32LT3170-STLA3-TR. “○” This symbol in the table means these parameters are for IS32LT3171-STLA3-TR. “♦” This symbol in the table means these limits are guaranteed at room temp TA = TJ = 25°C. “◊” This symbol in the table means these limits are guaranteed at full temp range TA = TJ = -40°C~125°C. Test condition is TA = TJ = -40°C~125°C, unless otherwise specified. Symbol Parameter VBD_OUT OUT pin breakdown voltage IEN Enable current RINT Internal resistor Condition VEN= 0V Typ. 0.35 VEN= 3.3V ○ 0.35 IRINT = 10mA ● VOUT = 1.4V, VEN = 3.3V, REXT OPEN ○ VOUT > 2.0V, VEN = 24V, REXT = 10Ω ● Output current Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 ○ Unit V ● VOUT > 2.0V, VEN = 3.3V, REXT = 10Ω Max. 42 VEN= 24V VOUT = 1.4V, VEN = 24V, REXT OPEN IOUT Min. mA 100 106 112 ♦ 9 10 11 ◊ 8 10 11 ♦ 9 10 11 ◊ 8 10 11 ♦ 110 116 122 ◊ 100 116 123 ♦ 110 116 122 ◊ 100 116 123 Ω mA mA 4 IS32LT3170/71 DC CHARACTERISTICS WITH STABILIZED LED LOAD “●” This symbol in the table means these parameters are for IS32LT3170-STLA3-TR. “○” This symbol in the table means these parameters are for IS32LT3171-STLA3-TR. Test condition is TA = TJ = -40°C~125°C, unless otherwise specified. Symbol Parameter VS Sufficient supply voltage on EN pin VHR Lowest sufficient headroom voltage on OUT pin Output current change versus ambient temp change ∆IOUT/IOUT (Note 3) Output current change versus Vout Condition Min. Typ. Max. ● 5 42 ○ 2.5 5.5 IOUT = 100mA 0.6 1 VOUT > 2.0V, VEN = 24V, REXT = 10Ω ● -0.26 VOUT > 2.0V, VEN = 3.3V, REXT = 10Ω ○ -0.26 VOUT > 2.0V, VEN = 24V, REXT = 10Ω ● 1.9 VOUT > 2.0V, VEN = 3.3V, REXT = 10Ω ○ Unit V V %/K %/V 1.9 Note 3: Guaranteed by design. Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 5 IS32LT3170/71 FUNCTIONAL BLOCK DIAGRAM IS32LT3170 IS32LT3171 Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 6 IS32LT3170/71 TYPICAL PERFORMANCE CHARACTERISTICS IS32LT3170 80 VEN = 42V REXT = 20Ω VEN = 42V REXT Open 25 Output Current (mA) Output Current (mA) 30 20 15 TA = 85°C TA = 25°C 10 TA = 125°C 0 0.5 2 3.5 5 6.5 8 9.5 11 12.5 60 TA = 125°C TA = 85°C 40 0 0.5 14 2 3.5 5 6.5 8 9.5 11 12.5 14 Output Voltage (V) Output Voltage (V) Figure 3 IOUT vs. VOUT Figure 2 IOUT vs. VOUT 180 150 VEN = 42V REXT = 7.5Ω 160 TA = 25°C TA = -40°C Output Current (mA) VEN = 42V REXT = 10Ω Output Current (mA) TA = -40°C 20 TA = -40°C 5 TA = 25°C 100 TA = 85°C TA = 125°C 50 TA = 25°C TA = -40°C 140 TA = 85°C 120 100 80 TA = 125°C 60 40 20 0 0.5 2 3.5 5 6.5 8 9.5 11 12.5 0 0.5 14 2 3.5 5 Output Voltage (V) Figure 4 IOUT vs. VOUT 9.5 11 12.5 14 Figure 5 IOUT vs. VOUT 200 VEN = 5V fPWM = 100Hz@1% Duty Cycle TA = 25°C 160 REXT = 10Ω 140 120 100 REXT= 20Ω 80 60 40 VEN = 42V TA = 25°C 180 REXT = 7.5Ω Output Current (mA) 180 Output Current (mA) 8 Output Voltage (V) 200 160 140 REXT = 7.5Ω REXT = 10Ω 120 100 REXT = 20Ω 80 60 40 REXT Open 20 0 6.5 REXT Open 20 0 2 4 6 8 10 12 Output Voltage (V) Figure 6 IOUT vs. VOUT Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 14 0 0 2 4 6 8 10 12 14 Output Voltage (V) Figure 7 IOUT vs. VOUT 7 IS32LT3170/71 80 20 VOUT = 2V REXT = 20Ω 16 TA = 25°C 12 8 Output Current (mA) Output Current (mA) VOUT = 2V REXT Open TA = 85°C TA = 125°C TA = -40°C TA = 25°C TA = 85°C 60 TA = -40°C TA = 125°C 40 20 4 0 5 15 25 0 42 35 5 15 25 VEN (V) 42 VEN (V) Figure 8 IOUT vs. VEN Figure 9 IOUT vs. VEN 150 200 TA = 85°C 120 90 TA = -40°C TA = 125°C VOUT = 2V REXT = 7.5Ω 175 TA = 25°C Output Current (mA) VOUT = 2V REXT = 10Ω Output Current (mA) 35 60 TA = 25°C TA = 85°C 150 125 TA = -40°C TA = 125°C 100 75 50 30 25 0 5 15 25 35 0 42 5 15 25 VEN (V) Figure 11 IOUT vs. VEN Figure 10 IOUT vs. VEN REXT = 7.5Ω IOUT = 0A REXT Open TA = -40°C 400 Supply Current (µA) Output Current (mA) 500 VOUT = 2V TA = 25°C 140 REXT = 10Ω 120 100 80 REXT = 20Ω 60 40 TA = 25°C 300 TA = 85°C 200 TA = 125°C 100 REXT Open 20 0 0 42 VEN (V) 180 160 35 5 10 15 20 25 30 35 VEN (V) Figure 12 IOUT vs. VEN Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 40 42 0 0 5 10 15 20 25 30 35 40 42 VEN (V) Figure 13 IEN vs. VEN 8 IS32LT3170/71 250 Output Current (mA) VEN = 42V VOUT = 2V 200 150 100 50 0 1 10 100 REXT (Ω) Figure 14 IOUT vs. REXT Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 9 IS32LT3170/71 IS32LT3171 80 VEN = 3.3V REXT = 20Ω VEN = 3.3V REXT Open 25 Output Current (mA) Output Current (mA) 30 20 15 TA = 25°C TA = 85°C 10 TA = -40°C TA = 25°C 60 TA = 85°C TA = 125°C 40 20 TA = 125°C 5 TA = -40°C 0 0.5 2 3.5 5 6.5 8 9.5 11 12.5 0 0.5 14 2 3.5 5 9.5 11 12.5 14 Figure 16 IOUT vs. VOUT Figure 15 IOUT vs. VOUT 180 150 VEN = 3.3V REXT = 7.5Ω 160 TA = 25°C TA = -40°C Output Current (mA) Output Current (mA) 8 Output Voltage (V) Output Voltage (V) VEN = 3.3V REXT = 10Ω 6.5 100 TA = 85°C TA = 125°C 50 TA = 25°C TA = -40°C 140 120 TA = 85°C 100 80 TA = 125°C 60 40 20 0 0.5 2 3.5 5 6.5 8 9.5 11 12.5 0 0.5 14 2 3.5 5 Output Voltage (V) Output Current (mA) Output Current (mA) 120 100 REXT= 20Ω 60 40 14 160 REXT = 7.5Ω 140 REXT = 10Ω 120 100 REXT = 20Ω 80 60 40 REXT Open REXT Open 20 0 12.5 VEN = 3.3V TA = 25°C 180 REXT = 10Ω 80 11 200 REXT = 7.5Ω 160 140 9.5 Figure 18 IOUT vs. VOUT VEN = 5V fPWM = 100Hz@1% Duty Cycle TA = 25°C 180 8 Output Voltage (V) Figure 17 IOUT vs. VOUT 200 6.5 20 0 2 4 6 8 10 12 Output Voltage (V) Figure 19 IOUT vs. VOUT Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 14 0 0 2 4 6 8 10 12 14 Output Voltage (V) Figure 20 IOUT vs. VOUT 10 IS32LT3170/71 80 20 VOUT = 2V REXT = 20Ω 16 12 TA = 25°C 8 Output Current (mA) Output Current (mA) VOUT = 2V REXT Open TA = 85°C TA = 125°C TA = -40°C TA = 25°C TA = 85°C 60 TA = 125°C TA = -40°C 40 20 4 0 0 2.5 3 3.5 4 4.5 5 2.5 3 3.5 4.5 5 VEN (V) VEN (V) Figure 22 IOUT vs. VEN Figure 21 IOUT vs. VEN 200 150 VOUT = 2V REXT = 10Ω TA = 85°C 120 90 TA = 25°C TA = -40°C TA = 125°C VOUT = 2V REXT = 7.5Ω 175 Output Current (mA) Output Current (mA) 4 60 TA = 25°C TA = -40°C 150 125 TA = 85°C TA = 125°C 100 75 50 30 25 0 2.5 3 3.5 4 4.5 0 5 2.5 3 3.5 500 REXT = 7.5Ω VOUT = 2V TA = 25°C IOUT = 0A REXT Open 400 140 Supply Current (µA) Output Current (mA) 5 Figure 24 IOUT vs. VEN Figure 23 IOUT vs. VEN 180 REXT = 10Ω 120 100 REXT = 20Ω 80 60 40 TA = -40°C TA = 25°C 300 200 TA = 85°C TA = 125°C 100 REXT Open 20 0 4.5 VEN (V) VEN (V) 160 4 2.5 3 3.5 4 4.5 5 0 0.5 1 1.5 2 2.5 3 VEN (V) VEN (V) Figure 25 IOUT vs. VEN Figure 26 IEN vs. VEN Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 3.5 4 4.5 11 5 IS32LT3170/71 250 Output Current (mA) VEN = 3.3V VOUT = 2V 200 150 100 50 0 1 10 100 REXT (Ω) Figure 27 IOUT vs. REXT Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 12 IS32LT3170/71 APPLICATIONS INFORMATION IS32LT3170/71 provides an easy constant current source solution for LED lighting applications. It uses an external resistor to adjust the LED current from 10mA to 150mA. The LED current can be determined by the Equation (1): I SET 10mA RINT REXT (1) REXT Where RINT (106Ω typ) is an internal resistor and REXT is the external resistor. Paralleling a low tolerance resistor REXT with the internal resistor RINT will improve the overall accuracy of the current sense resistance. The resulting output current will vary slightly lower due to the negative temperature coefficient (NTC) resulting from the self heating of the IS32LT3170/71. HIGH INPUT VOLTAGE APPLICATION When driving a long string of LEDs whose total forward voltage drop exceeds the IS32LT3170 VBD_OUT limit of 42V, it is possible to stack several LEDs(such as 2 LEDs) between the EN pin and the OUT pins 2,3, and 5 so the voltage on the EN pin is higher than 5V. The remaining string of LEDs can then be placed between power supply +VS and EN pin, (Figure 3). The number of LEDs required to stack at EN pin will depend on the LED’s forward voltage drop (VF) and the +VS value. When operating the chip at high ambient temperatures, or when driving maximum load current, care must be taken to avoid exceeding the package power dissipation limits. Exceeding the package dissipation will cause the device to enter thermal protection mode. The maximum package power dissipation can be calculated using the following Equation (2): PD ( MAX ) TJ ( MAX ) TA (2) JA Where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance; a metric for the relative thermal performance of a package. The recommended maximum operating junction temperature, TJ(MAX), is 125°C and so the maximum ambient temperature is determined by the package parameter; θJA. The θJA for the IS32LT3170/71 SOT23-6 package, is 94.8°C/W. Therefore the maximum power dissipation at TA = 25°C is: PD ( MAX ) +VS > 42V 125C 25C 1W 94.8C / W The actual power dissipation PD is: PD VOUT ( I EN I OUT ) 1 EN OUT To ensure the performance, the die temperature (TJ) of the IS32LT3170/71 should not exceed 125°C. The graph below gives details for the package power derating. 2,3,5 IS32LT3170 6 REXT GND (3) 4 1.2 REXT Note: when operating the IS32LT3170 at voltages exceeding the device operating limits, care needs to be taken to keep the EN pin and OUT pin voltage below 42V. THERMAL PROTECTION AND DISSIPATION The IS32LT3170/71 implements thermal foldback protection to reduce the LED current when the package’s thermal dissipation is exceeded and prevent “thermal runaway”. The thermal foldback implements a negative temperature coefficient (NTC) of -0.26%/K. Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 Power Dissipation (W) Figure 28 High Input Voltage Application Circuit SOT23-6 1 0.8 0.6 0.4 0.2 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (°C) Figure 29 PD vs. TA (SOT23-6) 13 IS32LT3170/71 The thermal resistance is achieved by mounting the IS32LT3170/71 on a standard FR4 double-sided printed circuit board (PCB) with a copper area of a few square inches on each side of the board under the IS32LT3170/71. Multiple thermal vias, as shown in Figure 5, help to conduct the heat from the exposed pad of the IS32LT3170/71 to the copper on each side of the board. The thermal resistance can be reduced by using a metal substrate or by adding a heatsink. Figure 30 Board Via Layout For Thermal Dissipation Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 14 IS32LT3170/71 CLASSIFICATION REFLOW PROFILES Profile Feature Preheat & Soak Temperature min (Tsmin) Temperature max (Tsmax) Time (Tsmin to Tsmax) (ts) Pb-Free Assembly 150°C 200°C 60-120 seconds Average ramp-up rate (Tsmax to Tp) 3°C/second max. Liquidous temperature (TL) 217°C Time at liquidous (tL) 60-150 seconds Peak package body temperature (Tp)* Max 260°C Time (tp)** within 5°C of the specified classification temperature (Tc) Max 30 seconds Average ramp-down rate (Tp to Tsmax) 6°C/second max. Time 25°C to peak temperature 8 minutes max. Figure 31 Classification Profile Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 15 IS32LT3170/71 PACKAGE INFORMATION SOT23-6 Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 16 IS32LT3170/71 RECOMMENDED LAND PATTERN Note: 1. Land pattern complies to IPC-7351. 2. All dimensions in MM. 3. This document (including dimensions, notes & specs) is a recommendation based on typical circuit board manufacturing parameters. Since land pattern design depends on many factors unknown (eg. user’s board manufacturing specs), user must determine suitability for use. Integrated Silicon Solution, Inc. – www.issi.com Rev. 0A, 08/04/2015 17