IS31LT3117-ZLS4-TR

IS31LT3117 53V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP July 2021 GENERAL DESCRIPTION FEATURES The IS31LT3117 is a 4-channel, linear regulated, constant current LED driver which can provide 4 equal currents outputs of up to 350mA per channel to drive high brightness LEDs over an input voltage range of 6V to 53V, while maintaining an output leakage current of less than 1µA. The output current is easily programmed using a single, tiny external resistor. The outputs of the IS31LT3117 can be connected in parallel to allow greater than 350mA output current.         The IS31LT3117 also features a PWM input to enable simple dimming control using a digital control signal. The recommended frequency range of the PWM signal is 4kHz ~ 100kHz. APPLICATIONS The IS31LT3117 provides a unique over temperature protection scheme. A hard shutdown which turns off all LED currents occurs if the die junction temperature exceeds the maximum value of 160°C. However, as the die junction temperature rises up to over 130°C (Typ.), the output current will begin to roll off at a rate of -2.22%/°C (Typ.). If the die temperature continues to rise above the hard shutdown temperature threshold, the LED currents will drop to zero. When temperature returns to 140°C (Typ.) or below, the hard shutdown protection is released and the chip will function again. 6V to 53V input supply voltage range Up to 1.4A total output current Over temperature protections Thermal current regulation above 130°C ±3% output current matching between channels PWM dimming and shutdown control input Optional 2.5V output to drive external standoff BJTs Very few external components  Industrial LED lighting  Low EMI lighting applications  Low-side constant current regulator The IS31LT3117 also has an optional 2.5V reference voltage output which is able to supply up to 10mA (typ.) output current. This voltage may be used to drive the base of the external BJTs for higher current applications in such case, driving for a wide varying input voltage is needed. The IS31LT3117 is offered in eTSSOP-16 package with operating temperature range of -40°C to +125°C. TYPICAL APPLICATION CIRCUIT Figure 1 Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 IS31LT3117 Directly Driving 4 LED Strings 1 IS31LT3117 VCC 6V ~ 53VDC COUT 33µF R5 3 8 VCC CIN 10µF RISET GND VLED1 PGND VLED2 VLED3 PWM Q5 Vb 1µF IS31LT3117 6 CPWM 1nF 1 RPWM 1kΩ 9 ISET 2,5 PWM VREF VLED4 16 14 Q1 R1 100nF Vb Q2 R2 Vb Q3 100nF R3 100nF Vb Q4 R4 Vb 100nF 12 10 Optional Figure 2 IS31LT3117 With Optional 2.5V Output Driving 4 External Standoff BJTs Note 1: The 33µF output capacitor should be placed as close to the LED array as possible in order to minimize the parasitic inductor effect due to the output wiring. Note 2: The resistor RISET should be place as close to ISET and GND pins as possible. Note 3: If you want less than four channels, the unused channel should be connected to GND. Note 4: RPWM and CPWM are optional to optimize PWM pin ESD performance. But a RC filter will degrade PWM dimming contrast ratio. Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 2 IS31LT3117 PIN CONFIGURATION Package Pin Configuration (Top View) eTSSOP-16 PIN DESCRIPTION No. Pin Description 1 PWM PWM control pin. (PWM=high, enable. PWM=low for 3.5ms, disable) 2, 5 PGND Power ground. 3 VCC Voltage supply input (6V~53V). 4,7,11,13,15 NC No connection. 6 GND Ground. 8 ISET A resistor from this pin to ground will set all the channel sink currents to the same value. 9 VREF 2.5V reference output capable of sourcing 10mA (Typ.). A 1µF capacitor must be connected from this pin to ground. 10,12,14,16 VLED4~VLED1 Current source outputs. Each channel should be connected to GND if it is not used. Thermal Pad Connect to ground. Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 3 IS31LT3117 ORDERING INFORMATION Industrial Range: -40°C to +125°C Order Part No. Package QTY IS31LT3117-ZLS4-TR IS31LT3117-ZLS4 eTSSOP-16, Lead-free 2500/Reel 96/Tube Copyright  ©  2021  Lumissil  Microsystems.  All  rights  reserved.  Lumissil  Microsystems  reserves  the  right  to  make  changes  to  this  specification  and  its  products  at  any  time  without  notice.  Lumissil  Microsystems  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.  Lumissil Microsystems 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 Lumissil Microsystems 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 Lumissil Microsystems is adequately protected under the circumstances Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 4 IS31LT3117 ABSOLUTE MAXIMUM RATINGS (NOTE 4) VCC pin to GND Voltage at PWM and VLEDx pins Voltage at ISET pin Current at VREF pin Junction temperature, TJ Storage temperature range, TSTG Operating temperature range, TA Power dissipation, PD(MAX) (Note 5) Thermal resistance, junction to ambient, still air, θJA ESD (HBM) ESD (CDM) -0.3V ~ +56V -0.3V ~ +56V -0.3V ~ +6.0V 10mA -40°C ~ +160°C -65°C ~ +150°C -40°C ~ +125°C 2.5W 39.9°C/W All pins pass 2kV, except all ground pin pass 1kV All pins pass 750V, except Pin 1 passes 100V Note 4: 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 5: Detail information please refers to package thermal de-rating curve on Page 13. ELECTRICAL CHARACTERISTICS Valid are at VCC = 12V, TA = TJ = -40°C ~ +125°C, typical value at 25°C, unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Unit VCC Supply voltage range 6.0 53 V RISET The ISET resistance 5.8 203 kΩ ISINK Output current per channel 367.5 mA IIN Quiescent Input supply current ISD Shutdown input current tSD The time of PWM pin keeping low to shutdown the IC RISET= 5.8kΩ, PWM= High VVLEDx= 1V, TA= 25°C 332.5 350 RISET= 5.8kΩ, PWM= High 13.8 RISET= 203kΩ, PWM= High 6.3 PWM= Low, VCC= 12V 90 3.5 mA µA ms fPWM The PWM dimming frequency VCC= 12V (Note 8) VHR Recommended VLED output voltage headroom ISINK= 350mA (Note 6) ILEAKAGE Leakage current per channel PWM= Low, VVLEDx= 53V tRISE Output current rise time RISET=5.8kΩ, PWM=20kHz, current rise from 10%~90% (Note 7) 300 ns tFALL Output current fall time RISET=5.8kΩ, PWM=20kHz, current fall down from 90%~10% (Note 7) 200 ns VISET ISET pin output voltage PWM pin input logic high voltage VPWM rising VPWML PWM pin input logic low voltage VPWM falling 100 0.8 kHz V 1 1.16 VPWMH Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 4 1.27 1.38 1.4 µA V V 0.4 V 5 IS31LT3117 ELECTRICAL CHARACTERISTICS (CONTINUE) Valid are at VCC = 12V, TA = TJ = -40°C ~ +125°C, typical value at 25°C, unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Unit TRO Thermal roll off threshold (Note 7) 130 °C TSD Thermal shutdown threshold Temperature rising (Note 7) 160 °C TSD-HYS Thermal shutdown hysteresis Temperature falling (Note 7) 20 °C ΔISINK/ISINK Current matching between Channels RISET= 5.8kΩ, PWM= High VVLEDx= 1V VREF Reference voltage output -3 2.32 2.5 3 % 2.76 V Note 6: It is a recommended value to ensure a better line regulation of 350mA output current. Note 7: Guarantee by design. Note 8: If add RC network on the PWM pin, the PWM dimming contrast ratio will be degraded and the recommended maximum PWM frequency is 50kHz. Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 6 IS31LT3117 TYPICAL PERFORMANCE CHARACTERISTICS 1.30 9.0 TA = 25ºC VCC = 12V 1.28 8.8 8.7 8.6 VISET (V) Supply Current (mA) 8.9 8.5 8.4 1.26 1.24 8.3 8.2 1.22 8.1 8.0 6 12 18 24 30 36 42 48 1.20 -40 54 -25 -10 5 Supply Voltage (V) Figure 3 35 50 65 80 95 110 125 Temperature (°C) Supply Current vs. Supply Voltage Figure 4 12 VISET vs. Temperature 2.60 TA = 25ºC VCC = 12V 2.58 11 2.56 10 VREF (V) Supply Current (mA) 20 9 8 2.52 2.50 7 6 -40 2.54 2.48 2.46 -25 -10 5 20 35 50 65 80 95 110 125 6 12 18 36 42 54 48 Supply Voltage (V) Temperature (°C) Figure 5 30 24 Figure 6 Supply Current vs. Temperature VREF vs. Supply Voltage 2.70 1.30 VCC = 12V TA = 25ºC 2.65 1.28 VREF (V) VISET (V) 2.60 1.26 1.24 2.55 2.50 1.22 1.20 2.45 6 12 18 24 30 36 42 48 54 60 2.40 -40 -25 -10 5 VISET vs. Supply Voltage Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 35 50 65 80 95 110 125 Temperature (°C) Supply Voltage (V) Figure 7 20 Figure 8 VREF vs. Temperature 7 IS31LT3117 400 350 VCC = 12V 300 VCC = 12V TA = 25ºC RISET = 5.8kΩ 300 250 200 150 RISET = 20kΩ Output Current (mA) Output Current (mA) 350 100 0 0 200 400 600 800 200 150 100 50 RISET = 200kΩ 50 250 0 1000 1200 1400 1600 1800 2000 0 50 100 VVLEDX (mV) Figure 9 200 RISET (kΩ) Output Current vs. VVLEDX Figure 10 400 Output Current vs. RISET 400 VCC = 12V RISET = 5.8kΩ fPWM = 4kHz,20kHz,100kHz 380 Output Current (mA) 350 Output Current (mA) 150 300 250 200 150 100 VCC = 12V 3 LEDs 360 340 320 300 280 260 240 50 0 220 0 20 40 60 80 100 200 -40 -25 -10 PWM Duty Cycle (%) Figure 11 Figure 13 Output Current vs. PWM Duty Cycle Output Current vs. VPWM on Rising Time Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 5 20 35 50 65 80 95 110 125 Temperature (°C) Figure 12 Figure 14 Output Current vs. Temperature Output Current vs. VPWM on Falling Time 8 IS31LT3117 FUNCTIONAL BLOCK DIAGRAM Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 9 IS31LT3117 APPLICATION INFORMATION FUNCTIONAL DESCRIPTION IS31LT3117 is a linear current regulator designed to drive high brightness LEDs. The device integrates 4 channels capable of driving up to 350mA in each channel and operates over a supply voltage range of 6V to 53V. Output current is easily programmed by using a single resistor. The IS31LT3117 incorporates a special thermal regulation protection feature which prevents the die temperature from exceeding the maximum rated junction temperature of 160°C. IS31LT3117 features a PWM/enable input which can be used to realize PWM dimming of the LEDs. In addition, the enable input can be used to put the device into a low power consumption shutdown mode. In shutdown, the device consumes only 80µA of supply current. VCC The VCC input pin provides power to the internal circuitry of the entire chip. The device supply current will vary with the output current setting due to the internal reference currents generated for each channel. The nominal supply current is 11.5mA (RISET=5.8kΩ) during operation. ISET sequence with the same initial propagation delay (typical 60ns) and interval delay time tINTDEL (typical 200ns). “First On First Off” ensures all channels are of the same pulse width as the input PWM signal. PWM IVLED1 IVLED2 IVLED3 IVLED4 tPG Figure 15 tINTDEL tPG tINTDEL PWM Dimming Sequential On/Off Note: there is a propagation time tPG from PWM rising/falling edge to the first channel activity, typical 60ns. GND Signal ground current return pin. PGND Power ground current return pin. This pin should be connected to as large as possible of a copper pad on the PCB to allow the best possible thermal performance of the circuit. The output current for the IS31LT3117 is set by connecting a resistor from the ISET pin to GND. An internal 1.27V reference voltage source will supply a current to the external current setting resistor. The reference current is internally amplified by a gain of 1600 to each of the 4 outputs. In order to have an accurate current output, this current setting resistor must be mounted as close to ISET and AGND pins as possible. It is recommended to maintain above a 0.8V VVLEDx to ensure a better line regulation of 350mA output current. PWM OUTPUT CURRENT When the PWM input pin is at low state (VPWM < 0.4V) and stays low for more than 3.5ms, the IS31LT3117 enters a low power consumption mode with all of the outputs turned OFF. In this mode, the IS31LT3117 consumes only 80µA of supply current. When the PWM input pin is at high state (VPWM > 1.4V), the IS31LT3117 will enters in operation mode to resume normal operation and all outputs are turned ON. A PWM input signal to the PWM pin can be used for HBLED dimming control. The recommended frequency range of PWM signal is 4kHz ~ 100kHz. To minimize power supply ripple and ground bounce, the IS31LT3117 integrates a sequential channel turn on/off function for the output channels VLEDx. On the rising PWM edge (propagation delay of typical 60ns), the output channels will be sequentially turned on from VLED1 to VLED4 with an interval delay time of tINTDEL (typical 200ns). On the falling PWM edge, the output channels will be sequentially turned off in the same The maximum sink current of all four channels are set by a single resistor (RISET) connected from the ISET pin to ground. The maximum possible current is 350mA per channel. However, any of the four channels can be connected in parallel to allow a larger current output. The channel sink current can be calculated by the following Equation (1): Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 VLEDx Constant current regulator channel. Each of the 4 input pins are capable of sinking up to 350mA of current with a headroom voltage VVLEDx of 0.8V (Min.). I SINKx  1600  VISET R ISET (1) Where VISET = 1.27V (Typ.) RISET need to be chosen 1% accuracy resistor with enough power tolerance and good temperature characteristic to ensure stable output current. The following table shows examples of ISINKX values for various RISET settings: 10 IS31LT3117 ISINKx (mA) RISET (kΩ) 10 203 100 20.3 350 5.8 R1 If less than 4 channels are required for a particular application, it is recommended to combine channels together to drive the LEDs. This will help to reduce the individual internal bias currents and, thus, the overall power consumption and heat dissipation of the device. For example, it can be configured to combine two or four channels to one channel to drive two or one string of LEDs. If only three channels are used, the unused channel should be connected to GND. ANALOG DIMMING The IS31LT3117 can also be dimmed by a voltage source applied directly through an external resistor to ISET pin (as the Figure 16). The R1 value can be chosen by below Equation (2): R1  1600  VDMAX I SINKx (2) Where, ISINKx is the desired maximum sink current of each channel, VDMAX is the maximum voltage of the dimming voltage source (VDIM). Then choose RISET by below Equation (3): RISET VISET  R1  VDMAX  VISET C1 0.1µF RISET Figure 16 Analog Dimming VREF When time of sinking a high current from a voltage source increases, the headroom voltage (VVLEDx) on the current sinks will also increase. This will cause an increase in power dissipation at the current sink, which may result in an increase of the package temperature. VVLEDx  VCC  VLEDS (5) Where VLEDS = total LED VF for the channel. To address this thermal condition, the IS31LT3117 integrates a 2.5V reference output which can be used to drive the base of an external BJT. This turns on the BJT and effectively clamps the voltage across the IS31LT3117’s output driver to approximately 0.8V. The power dissipation is then shared between the IC and the standoff transistor. The VREF pin can source up to 10mA of current to drive 4 external BJT’s, one for each channel. OPERATION WITH EXTERNAL BJTS (3) During this dimming method, the LEDs current of each channel is given by following Equation (4): V V  VISET I LED  1600   ISET  DIM R1  RISET ISET VDIM    (4) Where, VDIM is the voltage of the dimming voltage source. In most of the applications, the largest power dissipation will be caused by the current regulator. The thermal dissipation is proportional to the headroom voltage (VVLEDx) and the sink current flowing through it. When VCC is much higher than the VLEDS or ISINKx is large, the power dissipation of the IS31LT3117 will be high. This condition may easily trigger the over temperature protection (OTP). Using external standoff BJTs can transfer the unwanted thermal power from the current regulator channel to the BJTs (Figure 17). In this dimming, the dimming voltage source is inversely proportional to the LED current. That is, when the VDIM is maximum voltage, the output current is minimum, ideally zero, and when the VDIM is 0V, the output current is maximum. To avoid the noise coupling, it should place a 0.1µF capacitor close to the input of the dimming voltage source. Figure 17 IS31LT3117 with external BJTs With the external BJTs, the voltage across VLEDx to GND is given by Equation (6): Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 11 IS31LT3117 VVLEDx  VREF  VbeQ 5  R x  I beQx  VbeQx  VREF  VbeQ 5  R x  Rx  (6) I SINKx  VbeQx  1 Where VbeQ5 and VbeQx are the base-emitter voltage of Q5 and Qx, IbeQx is the base-emitter current of Qx.  is the gain of BJT. In order to ensure the normal operation, the voltage across VLEDx should not be lower than the minimum headroom voltage, minimum VHD (0.8V). So, VREF  VbeQ 5  R x  I SINKx  VbeQx  VHD  1  2 . 4  0 . 7  0 . 7  0 .8  115  0.35 200  1 IQ5  Therefore, 4 0.35 I SINKx  4  7 mA 200  1 X 1  1    PS  PQ 5  PR 5  VCC  (V REF  VbeQ 5 )  I Q 5 V REF  VbeQ 5  V beQ x  V HD (7) I SINKx  1 4 IQ5 I SINKx   X 1  1 (8) The PS is pretty low. So R5 can be eliminated. PR 5  R5  I Q 5 2 (9) The power on Q5 can be given by Equation (10):  PQx  VCC  V LEDS  VVLEDx   I SINKx  12  9.6  0.8   0.35  0.56W LED BRIGHTNESS CONTROL The power on R5 can be given by Equation (9):   12  2.4  0.7  0.007  0.0721W And, R5 can transfer the unwanted thermal power from Q5 to itself. Assume the current thought Q5 is IQ5,  I SINKx  1 By Equation (8), Therefore, Rx  V REF  VbeQ 5  VbeQx  V HD  PQ 5  VCC  V REF  VbeQ 5  R5  I Q 5  I Q 5 (10) An appropriate value of R5 should be chosen to ensure the power dissipation on Q5 won’t exceed the power rating of Q5. If the sum of total power of PR5 and PQ5 is low enough, R5 can be shorted and all power dissipates on Q5. The power on Qx can be calculated by Equation (11): PQx  VCC  V LEDS  VVLEDx   I SINKx (11) An appropriate value of Rx should be chosen to ensure the power dissipation on Qx won’t exceed the power rating of Qx. All of these BJTs should be set to operate in the linear region to ensure normal operation. For example, assume ISINKx =350mA, VCC=12V, VLEDS of three LEDs is 9.6V, the minimum  of the selected BJT is 200, the maximum base-emitter voltage of Q5 and Qx are all 0.7V, The minimum VREF pin output voltage is 2.4V, The Vbe of BJT is approximately 0.7V. Rx can be calculated from Equation (7): Lumissil Microsystems – www.lumissil.com Rev. C, 07/15/2021 IS31LT3117 allows user to control the LED intensity in two ways. First, the current sink level can be adjusted by changing the external resistance, or by using an external current source on the ISET pin to provide the reference current. However, the spectral output of the LED may shift slightly at different current levels, thus adversely affecting the color temperature of the light output. IS31LT3117 also provides a PWM input pin to control the ON/OFF state of all four channels. Using a PWM input signal of different duty cycle allows the average LED current to be adjusted linearly and proportional to the duty cycle, while maintaining the same peak current through the LEDs. In this way, the light intensity can be reduced without affecting the spectral content of the light, effectively dimming the light without changing the color temperature. TEMPERATURE REGULATION IS31LT3117 integrates a thermal regulation block which is designed to protect the IC from overheating when dissipating high power. If the junction temperature of the device exceeds 130°C (Typ.), the output current in each channel will begin to reduce linearly at a rate of -2.22% per °C and hence reduce the power dissipation of the IC. If the junction temperature of the IC continues to increase to the point where the thermal shutdown temperature of 160°C is reached or exceeded, the IC will automatically go into shutdown mode in which all of the four channel’s sink currents are reduced to a minimum. 12 IS31LT3117 If the junction temperature of the device is above 130°C (Typ.), and if thermal shutdown is not initiated, the output current will continue to regulate based on the junction temperature. In the temperature range 130°C