NCV7691D10R2G

NCV7691 Current Controller for Automotive LED Lamps The NCV7691 is a device which uses an external NPN bipolar device combined with feedback resistor(s) to regulate a current for use in driving LEDs. The target application for this device is automotive rear combination lamps. A single driver gives the user flexibility to add single channels to multichannel systems. A dedicated dimming feature is included via the PWM input pin. The individual driver is turned off when an open load or short circuit is detected. LED brightness levels are easily programmed using an external resistor in series with the bipolar transistor. The use of the resistor gives the user the flexibility to use the device over a wide range of currents. Multiple strings of LEDs can be operated with a single NCV7691 device. Set back power limit reduces the drive current during overvoltage conditions. The device is available in a SOIC8 package. www.onsemi.com 8 1 SOIC 8 CASE 751AZ MARKING DIAGRAM 8 NCV7691 ALYW G 1 Features • Constant Current Output for LED String Drive • External Bipolar Device for Wide Current Range Flexibility ♦ • • • • • • • • • • With BCP56 Transistor, Can Drive Multiple Strings Concurrently (ref. Datasheet Info) External Programming Current Resistor Pulse Width Modulation (PWM) Control Negative Temperature Coefficient Current Control Option Open LED String Diagnostic Short−Circuit LED String Diagnostic Multiple LED String Control Overvoltage Set Back Power Limitation SOIC8 Package AEC−Q100 Qualified and PPAP Capable These are Pb−Free Devices IC (Pb−Free) NCV7691 A L Y W G = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package PINOUT DIAGRAM VS SC PWM BASE FLTS NTC FB GND Applications • • • • • • ORDERING INFORMATION Rear Combination Lamps (RCL) Daytime Running Lights (DRL) Fog Lights Center High Mounted Stop Lamps (CHMSL) Arrays Turn Signal and Other Externally Modulated Applications General Automotive Linear Current LED Driver © Semiconductor Components Industries, LLC, 2015 August, 2017 − Rev. 5 Device Package Shipping† NCV7691D10R2G SOIC8 (Pb−Free) 3000 / Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. 1 Publication Order Number: NCV7691/D NCV7691 VS Short Circuit Sense Interface NCV7691 Base Drive SC BASE Feedback Circuit FB GND Reference “Short Circuit Detection with 4 or more channels” Figure .for circuit details Figure 1. Application Diagram MRA4003T3G Vbat 14V C1 0.1 mF R2 10 kW R3 1 kW VS BCP56 SC PWM BASE PWM Control Logic FLTS FB R1 NTC GND 1W C2 0.1 mF Figure 2. Microprocessor Controlled Application Diagram www.onsemi.com 2 NCV7691 Thermal Short−circuit Monitoring Detection − SC + Supply Monitoring 2V VS BASE Slew Rate Control PWM 1k Current Limitation Protection 120K FB − + − FLTS + Thermal Shutdown (Vref/2 or NTC/20) 76 mV Open Load Detection Vref Reference 0.4V to 2.1V NTC Selection NTC 10 152mV GND Figure 3. Block Diagram PIN FUNCTION DESCRIPTION SOIC8 Package Pin # Label 1 VS 2 PWM Logic input for output on/off control. Pull high for output on. 3 FLTS A capacitor to ground sets the time for open circuit, short circuit, and overtemperature detection. 4 NTC Optional input for Negative Temperature Coefficient performance. Ground this pin if Negative Temperature Coefficient is not used. 5 GND Ground 6 FB 7 BASE 8 SC Description Automotive Battery input voltage Feedback pin for current regulation Base Drive for external transistor (16 mA [min]) LED Short Circuit Detection Input. Ground pin if not used. www.onsemi.com 3 NCV7691 MAXIMUM RATINGS (Voltages are with respect to GND, unless otherwise specified) Rating Value Supply Voltage (VS) DC Peak Transient Unit V −0.3 to 50 50 High Voltage Pins (PWM, SC) Low Voltage Pins (FB, NTC) Low Voltage Pin (BASE) Fault Input / Output (FLTS) Junction Temperature, TJ Peak Reflow Soldering Temperature: Pb−Free, 60 to 150 seconds at 217°C (Note 1) −0.3 to (VS + 0.3) V −0.3 to 3.6 V −0.3 to 3.6 or VS + 0.6 whichever is lower V −0.3 to (VS + 0.3) *Internally limited charge voltage V −40 to 150 °C 260 peak °C Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality should not be assumed, damage may occur and reliability may be affected. 1. For additional information, please see or download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D and Application Note AND8003/D. ATTRIBUTES Characteristic Value ESD Capability Human Body Model Machine Model Charge Device Model ±4.0 kV ≥ ±200 V ≥ ±1 kV Moisture Sensitivity MSL2 Storage Temperature −55 to 150°C Package Thermal Resistance SOIC−8 Junction–to–Board, RYJB (Note 2) Junction–to–Ambient, RqJA Junction–to–Lead, RYJL 129°C/W 179°C/W 100°C/W 2. Values represent typical still air steady−state thermal performance on 1 oz. copper FR4 PCB with 650 mm2 copper area. www.onsemi.com 4 NCV7691 ELECTRICAL CHARACTERISTICS (4.5 V < VS < 18 V, CFLTS = 0.1 mF, R1 = 1 W, Transistor NPN = BCP56, −40°C ≤ TJ ≤ 150°C, unless otherwise specified) (Note 3) Characteristic Conditions Min Typ Max Unit VS = 14 V, PWM = 0 − 30 100 mA VS = 14 V, PWM = High Base current subtracted − 3.0 4.0 mA Supply Current in fault condition VS = 14 V, PWM = High VFLTS ≥ FLTS Clamp (5.0 V typ.) − 1.8 2.8 mA Under Voltage Lockout VS rising 3.5 4.0 4.5 V − 200 − mV 150 170 190 °C General Parameters Supply Current in normal condition Under Voltage Lockout Hysteresis Thermal Shutdown (Note 4) Thermal Hysteresis (Note 4) − 15 − °C Thermal Shutdown Delay (Note 4) 10 23 36 ms Output Source Current BASE = 1 V, FB = 0 V 16 25 30 mA Output Pull−Down Resistance PWM = 0 V, BASE = 1 V, FB = 0 V 0.5 1 2 kW Unity Gain Bandwidth − 100 − kHz Amplifier Trans−conductance − 30 − mA/mV 142 54 22 152 76 38 162 100 50 VS Overvoltage Fold Back Threshold 1 18.7 19.5 20.5 V VS Overvoltage Fold Back Threshold 1 Hysteresis − 700 − mV VS Overvoltage Fold Back Threshold 2 30.3 31.4 32.5 V VS Overvoltage Fold Back Threshold 2 Hysteresis − 700 − mV 8.0 8.5 8.8 V 1 2 3 mA 400 600 800 kW 1 1.15 1.3 V 4 5 6 V Base Current Drive Programming FB Regulation Voltage Under Voltage Lockout < VS < Over Voltage Fold Back Threshold 1 VS > Over Voltage Fold Back Threshold 1 VS > Over Voltage Fold Back Threshold 2 mV Open Load Timing VS Open Load Disable Threshold VS falling FLTS Charge Current PWM = 5 V, FB = 0 V, VS = 14 V FLTS Pull Down Resistor FLTS Threshold (Output Deactivation Threshold) FLTS Clamp VS = 18 V, (Note 7) PWM = 5 V, Charge Current activated Above this clamp voltage Charge current rolls off to 0 Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product performance may not be indicated by the Electrical Characteristics if operated under different conditions. 3. Designed to meet these characteristics over the stated voltage and temperature recommended operating ranges, though may not be 100% parametrically tested in production. 4. Guaranteed by design. 5. NTC = 400 mV is > NTC detection level and is a higher impedance than when operating within the detection level. 6. Evaluated at VS = 14V, (LED string current)max = 15 mA to 37 mA. 7. Device tested at 18 V. Upper limit of 6 V applies across the VS input supply range, but the maximum rating for FLTS (−0.3V to VS to −0.3V) must be considered for all system designs especially at the minimum extreme of VS = 4.5 V. www.onsemi.com 5 NCV7691 ELECTRICAL CHARACTERISTICS (4.5 V < VS < 18 V, CFLTS = 0.1 mF, R1 = 1 W, Transistor NPN = BCP56, −40°C ≤ TJ ≤ 150°C, unless otherwise specified) (Note 3) Characteristic Conditions Min Typ Max Unit VS − 1.7 VS − 2 VS − 2.3 V − 8 16 mA Input High Threshold − − 2.2 V Input Low Threshold 0.7 − − V Hysteresis − 0.35 − V Input Pull−down Resistor 30 120 190 kW Short Circuit Short Circuit Detection Threshold Short Circuit Output Current Current out of the SC pin PWM Temperature Compensation NTC Attenuation 0.4 V < NTC < 2.1 V − 1/10 − Regulation Offset (referenced to FB) 0.4 V < NTC < 2.1 V, VS = 14 V −2 −7 − − +2 +7 % mV NTC Input Pull−down Resistor NTC = 150 mV (low impedance) NTC = 400 mV (high impedance) (Note 5) 15 22 1 31 kW MW 170 220 300 mV NTC Detection Level AC Characteristics LED Current rise time 10% / 90% criterion, PWM rising (Note 6) 1 2.5 7.5 ms LED Current fall time 90% / 10% criterion, PWM falling (Note 6) 1 2.5 7.5 ms Propagation Delay PWM rising to IoutB/T 50% criterion (Note 6) − 5 15 ms Propagation Delay PWM falling to IoutB/T 50% criterion (Note 6) − 5 15 ms PWM Propagation Delay Delta |(Falling time) − (Rising time)| − 4 ms Delay Time VS to BASE VS rising through UVLO to BASE going high through 0.5 V CBASE = 50 pF, RBASE = 680 W PWM = VS, SC = floating, FB = GND, NTC = GND − 4 9 ms Open Load Blanking Delay FLTS capacitor charge time not included 25 42 70 ms Short Circuit Blanking Time 10 23 36 ms Power−Up Blanking Time 10 23 36 ms Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product performance may not be indicated by the Electrical Characteristics if operated under different conditions. 3. Designed to meet these characteristics over the stated voltage and temperature recommended operating ranges, though may not be 100% parametrically tested in production. 4. Guaranteed by design. 5. NTC = 400 mV is > NTC detection level and is a higher impedance than when operating within the detection level. 6. Evaluated at VS = 14V, (LED string current)max = 15 mA to 37 mA. 7. Device tested at 18 V. Upper limit of 6 V applies across the VS input supply range, but the maximum rating for FLTS (−0.3V to VS to −0.3V) must be considered for all system designs especially at the minimum extreme of VS = 4.5 V. www.onsemi.com 6 NCV7691 TYPICAL PERFORMANCE CHARACTERISTICS 270 Theta JA (5C/W) 250 230 210 1.0 OZ 190 170 2.0 OZ 150 0 100 200 300 400 500 600 700 800 900 Copper heat spreader Area (sqmm) Figure 4. qJA vs. Copper Spreader Area PCB Cu Area 100sqmm 1 oz 1000 = 0.5 DD = 0.5 100 R(t) (C/W) 0.2 0.1 0.05 0.02 10 0.01 SINGLE PULSE 1 0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000 Pulse Time (sec) Figure 5. Thermal Duty Cycle Curves on 650 mm2 Spreader Test Board 1000 2 2 mm 50 50 mm 100 mm2 500 mm2 R(t) 5C/W 100 10 1 0.000001 0.00001 0.0001 0.001 0.01 0.1 Time (Sec) 1 10 Figure 6. Single Pulse Heating Curve www.onsemi.com 7 100 1000 NCV7691 Detailed Operating Description a signal the buffer (U2) decreasing the base drive to the external transistor (BCP56). For loads above 150 mA, a PZT651device (replacing the BCP56) is recommended for stable operation. Normal operation includes a substantial voltage drop across the three LEDs limiting the power dissipation across the BCP56 transistor. Care must be taken when reducing the number of LEDs in the LED string for power considerations in the BCP56 and the Under Voltage Lockout performance. While the built in threshold for Under Voltage Lockout is specified at 4.0 V, another threshold is present at lower voltages (2.6 V) which could impact illuminations with the use of lower threshold voltage LEDs or lower string count. The NCV7691 device provides low−side current drive via an external bipolar transistor. The low voltage (152 mV) current sense threshold allows for maximum dropout voltage in the system. Dimming is performed using the dedicated PWM pin on the IC. Average output current is directly related to the intensity of the LED (or LED string). Output Drive Figure 7 shows the typical output drive configuration. A feedback loop regulates the current through the external LED. U1 monitors the voltage across the external sense resistor (R1). When the voltage exceeds the 152 mV reference, the output of U1 goes from high to low sending Vbat VS BASE BCP56 U2 FB − + R1 1W U1 152 mV GND Figure 7. Output Drive Configuration FLTS Reporting Latched off conditions can be reinitiated by a toggle of the PWM pin or a power down of the supply (VS). FLTS reports three fault conditions (by going high) all of which force the output off. • Open Circuit (latched) • Thermal Shutdown (thermal hysteresis) • Short Circuit (latched) www.onsemi.com 8 NCV7691 Open Load Detection When an open load is detected, the output turns off, and can be turned back on again by a toggle of the PWM pin or a power down of the supply (VS). If the open load feature is not used, FLTS should be tied to GND. Grounding FLTS disables open load detection. Short circuit detection and thermal shutdown functions remain active but are not reported externally. The BASE pin is actively held low in this case. Faulted output strings due to open load conditions sometimes require the complete shutdown of illumination within an automotive rear lighting system. The NCV7691 provides that feature option. There are two open load detections schemes in the NCV7691. These are OR’d conditions. 1. In normal regulation, the IC monitors the FB voltage (typ 152 mV). When this voltage falls by 50% (to typ 76 mV), an open circuit is detected and a current starts to charge FLTS to flag open load, once FLTS voltage crosses the output deactivation threshold the driver is switched off resulting in a latched off−state. When regulating via the NTC pin, the open load detection threshold is V(NTC)/20. 2. During open load, the base current increases to try and satisfy the regulation loop. Internal circuitry monitors the base current. When the Base Current Drive reaches the Output Source Current (typ 25 mA) threshold, an open circuit is flagged and the driver is latched off. VS VS Open Load Disable FLTS Clamp (V) FLTS Charge Current 2mA VS Monitoring Output Drive BASE BCP56 Detect Blanking Timer (42 ms) FLTS VS FB − Two schemes are used should the rise in base current create a regulated voltage on the feedback pin (FB). If this occurs scheme #1 would not detect the open load. R1 1 ohm + 600 kW C2 0.1uF Output Deactivation Threshold 1.15V GND Open load can be disabled by connecting FLTS to GND. Figure 8. Open Load Detection Circuitry Table 1. OPEN LOAD DETECTION Open Load (VS > Open Load Disable Threshold) FLTS BASE No Open Load (with FLTS capacitor) Normal Operation (held low) regulation No Open Load Grounded regulation FB = 1/2 regulation (with FLTS capacitor) FLTS starts charging Held low via internal pull−down resistor after time−out. BASE Current > 25 mA [typ] (with FLTS capacitor) FLTS starts charging Held low via internal pull−down resistor after time−out. FB = 1/2 regulation Grounded Actively held low. BASE Current > 25 mA [typ] Grounded Actively held low. Multiple String Open Load Consideration One of the ways to improve the open load detection capability is more precise external BASE current limitation. An example of the circuit with one extra resistor and PNP bipolar is shown in Figure 9. In multi−string applications with high−beta transistors, the feedback voltage from individual strings is averaged, so one defective LED string does not always lead to the open load detection. www.onsemi.com 9 NCV7691 BCP56 ~ 9.3mA ~ 0.1mA NCV7691 ~ 10mA Figure 11 shows the proper wired “OR” connection for applications which require all channels to latch−off with an open load condition. An open load condition will be reported back to the microprocessor regardless of which channel it occurs on. Note the NCV7691 device uses a feature which allows any channel to charge the FLTS capacitor due to its definition at a charge current value much higher than the discharge value (2 mA versus 600 kW [typ]). Additional NCV7691 Single Current Controller devices device may share the same common FLTS capacitors in systems requiring multiple ICs. BCP56 45mV 14mV max. 47R 30mA 1R5 1R5 10.9mA BASE 57.3mV FLTS Clamp (V) FLTS Charge Current 2mA − to microprocessor Figure 9. Improved Open Load Detection for Multiple Strings + FLTS BSS138 600k FLTS pull−down resistor System Voltage and Overvoltage Fold−back Low voltage system operation is typically limited by head room in the LED string. Because of this limitation, detection of open loads is inactive below VS = typ 8.5 V (Open Load Disable voltage). There is also an upper limitation. The current roll off feature of the part resets the loop at a lower reference voltage and consequential lower current for VS above the Overvoltage Fold−back threshold on VS, (typ 19.5 V). The open load Detection circuitry is inactive for VS above this Overvoltage Fold−back threshold voltage. C1 0.1uF Output Deactivation Threshold 1.15V GND Figure 10. Open Drain Output Interface to Microprocessor Open Load Timing FLTS The timing for open load detection is programmed using the FLTS pin. The NCV7691 device regulates a 152 mV reference point (Figure 8 on the feedback pin (FB)). When the voltage decreases (half of the FB Regulation Voltage) or the base current reaches the internal 25 mA (typ) limit for 42 ms the timer associated with the FLTS pin starts by charging the capacitor with a 2 mA current source. When the voltage on FLTS exceeds the output Deactivation Threshold (1.15 V (typ)), the BASE pin is pulled low and is held low by an internal pulldown resistor. A 42 ms blanking time during power up ensures there is enough time for power−up to eliminate false open−load detections. The slow FLTS discharge (600 kW [typ]) load (and resultant long time to restart LED drive) eliminates flickering effects. NCV7691 GND to microprocessor NCV7691 FLTS Clamp (V) FLTS Charge Current 2mA − + FLTS BSS138 600k FLTS pull−down resistor C1 0.1uF − BC856 V(FB) < 75 mV −> −> FLTS current source active −> −> LEDs off + GND − FB + SC Output Deactivation Threshold 1.15V GND Note – Only one timing capacitor and interface transistor are required for system operation. FLTS Interface Figure 10 shows an open−drain logic level FET serving as a buffer to the microprocessor. Figure 11. FLTS Wired OR to Microprocessor www.onsemi.com 10 NCV7691 Temperature Compensation a positive temperature coefficient. The regulation loop voltage on NTC should be sufficiently higher than the 220 mV reference voltage to avoid interactions. A typical regulation voltage of 1.6 V is suggested. The overall tolerance specification for the NTC functionality is broken down into two components. 1. Absolute error. A ±2% tolerance is attributed to the expected value as a result of internal circuitry (most predominantly the 1/10 resistor divider). 2. Reference error. A ± 7mV offset mismatch in the circuitry referenced to FB. This provides a part capability of (V(NTC)/10) x 0.98 −7mV < V(FB) < (V(NTC)/10) x 1.02 + 7mV. In addition to the temperature coefficient of the Zener diode (D1), a PTC resistor (R2) can be used to enhance the effect of the overall negative temperature coefficient. A positive temperature coefficient resistor at the top of the resistor divider creates a negative temperature coefficient at the resistor divider output. Alternatively, a negative temperature coefficient resistor for R3 would have the same effect. The NCV7691 device typically operates with a zero TC output current source. The NTC (Negative Temperature Coefficient) pin provides an alternative for an output current which degrades with temperature as defined by the designer’s external components. Zero TC operation is provided when the NTC pin is connected to GND. When a negative temperature coefficient output current is desired to compensate for effects of external LED illumination, the setup shown in Figure 12 will provide the function. On the NTC pin, a comparator detects when the voltage is higher than typ 220 mV, and this voltage is used to provide the feedback reference voltage for the current feedback regulation loop. The zener provides a reference voltage for the negative temperature coefficient NTC device through an external divider. Be careful of your choice of the zener diode as the temperature coefficients of the devices have a wide variation with the low voltage zeners having a high negative temperature coefficient and the high voltage zeners having VS VS R1 BASE − R2 D1 SZMM3Z4V7T1G 4.7 V (typ) NTC FB + 0.4 V to 2.1 V R3 H L 152 mV GND L H + − 220 mV Figure 12. Negative Temperature Compensation Operation www.onsemi.com 11 NCV7691 Short Circuit Detection (S1). The comparator connected between VS and SC is referenced to a voltage 2.0 V down from VS. A detection voltage less than 2.0 V will toggle a signal from the comparator to the output drive buffer turning off output drive (BASE) to the external bipolar transistor. An initial blanking time of 23 ms is used during turn−on of the device to ignore false detections. This is beneficial during normal operation and when the device is used without a microprocessor input (PWM) interface as in Figure 13. Switching off the Base−driver in case of SC, will also make the FLTS charge active, indicating the error to the microprocessor. When having multiple channels an isolation might be needed to provide the appropriate voltage back to the SC pin during short circuit. Figure 14 shows how external diodes can provide this feature. The short circuit (SC) pin of the device is used as an input to detect a fault when the collector of the external bipolar transistor is shorted to the battery voltage. The threshold voltage detection is referenced 2.0 volts down from the VS pin. A voltage of less than 2.0 volts between VS and SC will latch the device off. The PWM pin must be toggled or UVLO event must occur to reinitiate a turn−on. The detection time for this event is swift to protect the external transistor. To maintain operation during transient events down to 4.5 V, the short circuit detection circuitry is inactive below VS = typ 8.5 V. (the same Open Load Disable voltage as used to disable Open load detection). Otherwise false short circuit events could be falsely triggered due to non−conduction of the external LEDs during transients. Figure 13 shows a short circuit event modeled as a switch S1 MRA4003T3G Vbat 14V C1 0.1uF SC VS BCP56 Output Drive to microprocessor BASE FLTS Clamp 5V Blanking Timer (23 ms) 2mA FLTS BSS138 R2 10 Kohm + Short Circuit Detection Threshold − 2V FB R1 1 ohm C2 0.1uF 600 kW GND Short Circuit Detection is disabled below 8.5 V (typ). Figure 13. Short Circuit Detection www.onsemi.com 12 NCV7691 Short Circuit Detection with 4 or more Channels Figure 15 shows an implementation which will work provided the drop across the loads is < 3.4 V. This limitation is due to the SC minimum specification of VS − 1.7 V. This setup saves the user 2 diodes. Interfacing the short circuit detection for multiple channels with one NCV7691 driver system is done easily using diodes or a diode resistor combination depending on your system requirements. Figure 14 shows the implementation using 4 individual diodes which will work for all applications. LOAD2 LOAD1 Q1, BCP56 D1 D2 D3 D4 LOAD3 Q2, BCP56 Ib(Q1) LOAD4 Q3, BCP56 Q4, BCP56 Ib(Q3) Ib(Q2) Ib(Q4) R2 R3 R8 R9 R1 R4 R10 R5 R11 SC BASE FB GND Figure 14. Short Circuit Detection with 4 or more Channels LOAD2 LOAD1 LOAD3 LOAD4 R6, 680 Ohms R12, 680 Ohms R7, 680 Ohms R13, 680 Ohms Q1, BCP56 D1 D2 Q2, BCP56 Ib(Q1) R2 Q3, BCP56 Q4, BCP56 Ib(Q3) Ib(Q2) Ib(Q4) R3 R8 R9 R1 R4 R5 R10 SC BASE FB GND Figure 15. Saving Two Diodes for Short Circuit Protection www.onsemi.com 13 R11 NCV7691 Thermal ShutDown Stoplight / Tail Light Application The thermal shut down circuit checks the internal junction temperature of the device. When the internal temperature rises above the Thermal shutdown threshold for greater than the thermal shutdown filter time (23 ms [typ]) the device is switched off. The filter is implemented to achieve a clean detection. Switching off the Base−driver in case of TSD, will also make the FLTS charge active, indicating the error to the microprocessor. Automotive applications have a need to drive the RCL (Rear Combination Light). Combining the NCV7691 with the NCV1455B device accomplishes that task. Figure 17 shows the interface of the two ICs using an additional diode (D2). The STOP input signal provides a signal to the NCV7691 which will provide a 100% duty cycle output to the LED strings whenever STOP is high. When only TAIL is high, a modulated duty cycle input is provided to the PWM input and also provides power to the NCV7691 and the LED string. The NCV1455B can provide up to 200 mA (albeit with a 2.5 V drop at 200 mA) of output drive current. If your application exceeds the current capability of the NCV1455B (200mA) two extra diodes will be required as shown in Figure 18. In this case, the current flow through the LEDs will come from STOP and/or TAIL eliminating the high current from the NCV1455B. Applications Direct Drive without direct battery connection: Some applications may not allow for a direct connection of VS to the battery voltage. These applications require a connection with a smart−FET. Figure 16 highlights this setup. MRA4003T3G C5 0.1uF Channel Control Vbat 14V BCM C1 0.1uF R2 10 k VS SC R3 10 k PWM BASE FLTS FB BCP56 GND NTC R1 1 C4 0.1uF Figure 16. SmartFET Control D1 MRA4003T3G STOP (Vbat) C5 0.1uF TAIL D2 MRA4003T3G C1 0.1uF GND VCC TRIG DIS OUT THRES RESET R3 10 k R2 10 k VS SC PWM BASE FLTS FB BCP56 CV GND NTC NCV1455B* C4 0.1uF NCV7691 Figure 17. Stoplight / Taillight Application www.onsemi.com 14 R1 1 NCV7691 TAIL STOP D1 MRA4003T3G C5 0.1uF D2 MRA4003T3G GND D3 SBAV70L C1 0.1uF GND TRIG DIS OUT THRES RESET R2 10 k VCC VS D4 SBAV70L R3 10 k SC PWM BASE FLTS FB BCP56 CV NTC NCV1455B* C4 0.1uF GND NCV7691 Figure 18. Stoplight / Taillight Application at higher currents www.onsemi.com 15 R1 NCV7691 R1 is used to limit current in the event of an open circuit on one of the strings. Figure 21: Open Circuit. It shows the change in BASE drive which occurs with an open circuit in one of the strings. The drive current out of BASE changes from (Ib(Q1)+ Ib(Q2)) to (Ib(Q1)+Ic(Q2)) as regulation will try to maintain in the loop to get 152 mV on FB. Figure 22 shows the equivalent circuit when an open load occurs. Figure 19: Application Diagram with no microprocessor. A resistor pull−up from PWM to VS illustrates how the device can be used as a standalone LED driver without using a microprocessor to drive the PWM input. Figure 20 along with Figure 21 and Figure 22 highlight the use of the NCV7691 device with multiple strings connected to a common drive BASE pin and using external resistors to tie additional strings to a common feedback point (FB). The FB pin will maintain regulation with the FB pin at 152 mV. LOAD1 MRA4003T3G LOAD2 R6 Vbat 14V R7 Q1, BCP56 Q2, BCP56 Ib(Q1) C1 0.1uF R2 10 Kohm R3 10 Kohm VS Ib(Q2) R2 BCP56 SC R3 R1 PWM BASE R4 NTC R5 FB FLTS R1 1 ohm GND SC BASE C2 0.1uF FB GND Figure 19. Application Diagram with No Microprocessor Figure 20. Driving Multiple Strings X LOAD1 (Because of the SC minimum specification limitation of VS − 1.7 V, resistors R6 and R7 will need to be replaced by diodes if the drop across the load is >3.4 V) LOAD2 R6 LOAD1 R6 R7 Q2, BCP56 Q1, BCP56 Ib(Q1) Ib(Q1) Q1, BCP56 Q2, BCP56 Ic(Q2) Ib(Q2) R2 R3 R2 R3 R1 R4 R1 R5 R4 SC BASE SC FB BASE GND FB (Because of the SC minimum specification limitation of VS − 1.7 V, resistors R6 and R7 will need to be replaced by diodes if the drop across the load is >3.4 V) GND Figure 21. Open Circuit Figure 22. Open Circuit Equivalent www.onsemi.com 16 R5 NCV7691 Table 2. FAULT HANDLING TABLE Driver Condition During Fault Driver Condition after Parameters Within Specified Limits Output Fault Clear or Operation Restitution Requirement Fault Memory Sense Condition Open Load (FLTS active) Latched off. 42 ms w / FB < Vref/2 76 mV or Ibase > 25 mA 8.5 V < VS < 19.5 V Driver is latched Off. Driver is latched Off. Toggle PWM pin. VS power down below UVLO. FLTS low to high Open Load (FLTS = GND) No effect. n/a No effect. No effect. n/a n/a Short Circuit to Vbat (FLTS active) Latched off. 23 ms SC < VS − 2 V VS > 8.5 V Driver is latched Off. Driver is latched Off. Toggle PWM pin. VS power down below UVLO. FLTS low to high Short Circuit to Vbat (FLTS = GND) Latched off. 23 ms SC < VS − 2 V VS > 8.5 V Driver is latched Off. Driver is latched Off. Toggle PWM pin. VS power down below UVLO. FLTS low to high Under Voltage Lockout Driver Off VS < 4 V Driver Off Driver back on. VS > 4 V minus 200mV hysteresis. n/a Over Voltage Output Current Reduced Threshold 1 VS > 19.5 V Threshold 2 VS > 31 V Reduced output current (FB Regulation Voltage) Driver back to normal operation. VS < threshold minus 700 mV hysteresis. n/a Thermal Shutdown (FLTS active) Driver Off 23 ms TJ > 170°C Driver Off Driver back on. Die temperature below shutdown hysteresis FLTS low to high Thermal Shutdown (FLTS =GND) Driver Off 23 ms TJ > 170°C Driver Off Driver back on. Die temperature below shutdown hysteresis FLTS low to high Fault NOTE: All specified voltages, currents, and times refer to typical numbers. www.onsemi.com 17 Fault Reporting MECHANICAL CASE OUTLINE PACKAGE DIMENSIONS SOIC−8 CASE 751AZ ISSUE B 8 1 SCALE 1:1 NOTES 4&5 0.10 C D 45 5 CHAMFER D h NOTE 6 D A 8 DATE 18 MAY 2015 H 2X 5 0.10 C D E E1 NOTES 4&5 L2 1 0.20 C D 4 8X B NOTE 6 TOP VIEW b 0.25 M L C DETAIL A C A-B D NOTES 3&7 NOTE 7 c 0.10 C e A1 C SIDE VIEW NOTE 8 DIM A A1 A2 b c D E E1 e h L L2 DETAIL A A2 A SEATING PLANE NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSION b DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE PROTRUSION SHALL BE 0.004 mm IN EXCESS OF MAXIMUM MATERIAL CONDITION. 4. DIMENSION D DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006 mm PER SIDE. DIMENSION E1 DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.010 mm PER SIDE. 5. THE PACKAGE TOP MAY BE SMALLER THAN THE PACKAGE BOT­ TOM. DIMENSIONS D AND E1 ARE DETERMINED AT THE OUTER­ MOST EXTREMES OF THE PLASTIC BODY AT DATUM H. 6. DIMENSIONS A AND B ARE TO BE DETERMINED AT DATUM H. 7. DIMENSIONS b AND c APPLY TO THE FLAT SECTION OF THE LEAD BETWEEN 0.10 TO 0.25 FROM THE LEAD TIP. 8. A1 IS DEFINED AS THE VERTICAL DISTANCE FROM THE SEATING PLANE TO THE LOWEST POINT ON THE PACKAGE BODY. SEATING PLANE END VIEW RECOMMENDED SOLDERING FOOTPRINT* MILLIMETERS MIN MAX --1.75 0.10 0.25 1.25 --0.31 0.51 0.10 0.25 4.90 BSC 6.00 BSC 3.90 BSC 1.27 BSC 0.25 0.41 0.40 1.27 0.25 BSC GENERIC MARKING DIAGRAM* 8X 0.76 8 8X 1.52 1 7.00 XXXXX A L Y W G 1 1.27 PITCH DIMENSIONS: MILLIMETERS *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. DOCUMENT NUMBER: DESCRIPTION: 98AON34918E SOIC−8 XXXXX ALYWX G = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package *This information is generic. Please refer to device data sheet for actual part marking. Pb−Free indicator, “G”, may or not be present. Electronic versions are uncontrolled except when accessed directly from the Document Repository. Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red. PAGE 1 OF 1 ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor reserves the right to make changes without further notice to any products herein. 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