CAT4106 6 W Quad Channel DC/DC LED Driver with Diagnostics Description http://onsemi.com 1 PIN CONNECTIONS 1 LED1 GND FAULT PGND FB SW EN/PWM NC LED1 GND FAULT PGND 1 VFMAX VFMIN CTRL VIN TAB is GND NC EN/PWM SW FB Four LED Channels with Tight Current Matching Integrated DC/DC Boost Converter Up to 6 W LED Total Output Power Up to 92% Efficiency Low Dropout LED Channels (500 mV at 175 mA) High Frequency PWM Interface (up to 2 kHz) Adjustable Short/Open LED Detection Programmable LED Channel Current Adjustable LED Channel Voltage Thermal Shutdown Protection 16−lead TQFN 4 x 4 mm and TSSOP Packages These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant LED2 LED3 LED4 RSET VFMAX VFMIN CTRL VIN TAB is GND Features • • • • • • • • • • • • 1 TSSOP−16 YP SUFFIX CASE 948AP TQFN−16 HV4 SUFFIX CASE 510AE RSET LED4 LED3 LED2 The CAT4106 is an integrated multi−channel LED driver and high power DC/DC converter suitable for powering backlighting applications up to a total of 6 watts. Up to four matched LED strings can be accurately programmed with uniform drive current set by a single external resistor. Each output channel is suitable for LED string voltages of up to 36 V. The driver automatically adjusts the output voltage to drive the highest forward voltage string with the minimum headroom voltage maximizing the efficiency. High resolution dimming control is achieved by the EN/PWM logic pin which supports multiple frequencies. This ensures precise PWM dimming control while the device remains fully biased. In addition, when held at logic low, the device to enter a full shutdown “zero” current mode. External programming resistors set the minimum and maximum voltage limits for the acceptable “window of operation” for LED strings. Any channel which fails to regulate within the window (Open or Short LED) is detected and flagged on the FAULT logic output (active low, open−drain). The device is available in a 16−lead TQFN 4 mm x 4 mm and TSSOP with exposed pad packages. (Top Views) MARKING DIAGRAMS 4106Y CDAL CDAL = CAT4106HV4−GT2 4106Y = CAT4106YP−T2 Applications • LCD Backlight Lighting • Automotive and General Purpose Lighting ORDERING INFORMATION Device Package Shipping CAT4106HV4−GT2 (Note 1) TQFN−16 (Pb−Free) 2,000/ Tape & Reel CAT4106YP−T2 (Note 1) TSSOP−16 (Pb−Free) 2,000/ Tape & Reel 1. NiPdAu Plated Finish (RoHS−compliant) 2. Matte−Tin Plated Finish (RoHS−compliant) © Semiconductor Components Industries, LLC, 2010 March, 2010 − Rev. 0 1 Publication Order Number: CAT4106/D CAT4106 L VL C2 3 V to 24 V C3 10 mF/ 50 V 47 mH 4.7 mF VIN VIN 3 V to 5.5 V C1 1 mF R4 R6 SW VFMAX VFMIN R5 CAT4106 OFF... ON... DIM R1 D R7 EN/PWM RSET LED1 LED2 LED3 R2 20 kW LED4 CTRL FAULT FB GND PGND R3 20 kW VIN R8 LED Fault Detection (open drain pull−down) Figure 1. Typical Application Circuit Table 1. ABSOLUTE MAXIMUM RATINGS Parameters Ratings Units VIN, RSET, EN/PWM, CTRL, FB, FAULT −0.3 V to 6 V VFMIN, VFMAX −0.3 V to 6 V LED1, LED2, LED3, LED4 −0.3 V to 25 V SW (internally clamped to 40 V) 50 V Storage Temperature Range −65 to +160 _C Junction Temperature Range −40 to +150 _C 300 _C Lead Temperature Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Table 2. RECOMMENDED OPERATING CONDITIONS Parameter Range Units VIN 3.0 to 5.5 V Inductor Drive Voltage 3.0 to 24 V LED String Forward Voltage per channel up to 36 V Ambient Temperature Range −40 to +85 _C ILED per LED pin 10 to 175 mA 3. Typical application circuit with external components is shown above. Table 3. RECOMMENDED EN/PWM TIMING (For 3.0 ≤ VIN ≤ 5.5 V, over full ambient temperature range −40 to +85°C.) Name Min Typ Max Units LED setup time from shutdown 10 40 100 ms TLO EN/PWM low time 0.2 2000 ms THI EN/PWM high time 0.2 Symbol TLEDSETUP TPWRDWN TLEDSET Conditions ms EN/PWM low time to shutdown delay 8 LED current settling time ILED = 100 mA http://onsemi.com 2 0.2 ms ms CAT4106 TLEDSETUP THI TPWRDWN TLO EN/PWM SHUTDOWN DIMMING 100% BRIGHTNESS POWERDOWN SHUTDOWN LED CURRENT DEVICE QUIESCENT CURRENT Figure 2. CAT4106 EN/PWM Timing Table 4. ELECTRICAL OPERATING CHARACTERISTICS VIN = 5 V, VL (inductor drive voltage) = 12 V, TAMB = 25°C (over recommended operating conditions unless specified otherwise) Symbol IQ Description Conditions Min Max Units 2.5 2.0 3.4 2.9 3.5 3.0 4.4 3.9 mA 1 mA 1.3 V V kW VIN Operating Current Switching Not Switching Switching Not Switching ISD VIN input shutdown Current VEN = 0 V VIH VIL REN EN/PWM Logic High Threshold Logic Low Threshold Internal Pull−Down Resistor Device Enable Level Disable/PWM Level VUVLO Undervoltage lockout (UVLO) VIN pin voltage TSD Thermal Shutdown Threshold THYS Thermal Hysteresis VRSET RSET regulation voltage 10 mA < IRSET < 2 mA RSET to LED Current gain ratio 30 mA LED current 100 LED Channel Dropout Voltage ILED = 175 mA 0.5 DILED LED Channel Matching 0.5 V < VLED < 5 V ILED−OFF LED Channel leakage Channel is Off VVFMAX O/C Detect voltage threshold VVFMIN S/C Detect voltage threshold VCTRL ICTRL CTRL pin voltage accuracy CTRL pin maximum load Offset to Lowest LED output IFAULT Pull−down Drive Current Open Drain Leakage Current FAULT is Active (0.1 V bias) FAULT is Inactive 1 2 FB Pin control voltage FB pin input leakage current Normal switching mode regulation ILED/IRSET VDO VFB IFB FSW ISWMAX RSW DCMAX DCMIN ISWLEAK OVPSW SW Pin Switching Frequency Switch Pin Current Limit Switch Pin On−resistance Maximum Duty Cycle Minimum Duty Cycle Switch Leakage Current Over Voltage Protection Detect (ILED = 30 mA) (ILED = 30 mA) (ILED = 60 mA) (ILED = 60 mA) Typ 0.4 100 0.8 0.7 200 300 2.0 V 150 _C 20 ISW = 500 mA Prior to Current Limiting Prior to Pulse−Skipping VSW = 20 V Enters Low Power mode http://onsemi.com 3 1.17 −5 1.20 ±1 _C 1.23 V V +5 % 1 mA 1.25 V 1.15 1.20 1.15 1.20 1.25 V − 0.1 25 0 + 0.1 V mA 1 mA mA 285 300 315 1 mV mA 0.7 0.8 1.0 1.0 1.0 96 5 1.3 MHz A W % % mA V 5 40 CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS 1.30 6 1.25 switching 4 not switching 2 RSET VOLTAGE (V) 0 0 0.5 1.0 1.5 1.20 1.15 1.10 2.0 3.5 4.0 4.5 5.0 VIN SUPPLY (V) Figure 3. Quiescent Current vs. RSET Current Figure 4. RSET Voltage vs. VIN Supply 1.30 140 1.25 120 1.20 1.15 5.5 100 80 0 50 100 60 150 20 60 100 140 TEMPERATURE (°C) LED CURRENT (mA) Figure 5. RSET Voltage vs. Temperature Figure 6. ILED/IRSET Gain vs. LED Current 200 175 175 150 150 LED CURRENT (mA) 200 125 100 75 50 180 125 100 75 50 25 25 0 3.0 RSET CURRENT (mA) 1.10 −50 LED CURRENT (mA) RSET VOLTAGE (V) 8 GAIN QUIESCENT CURRENT (mA) (VIN = 5 V, VL = 12 V, TAMB = 25°C, typical application circuit unless otherwise specified.) 0 0.2 0.4 0.6 0.8 0 1.0 3.0 3.5 4.0 4.5 5.0 5.5 LED PIN VOLTAGE (V) VIN SUPPLY (V) Figure 7. LED Channel Current vs. LED Pin Voltage Figure 8. LED Channel Current vs. VIN Supply http://onsemi.com 4 CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS 0.9 30 0.8 25 FAULT DRIVE RDSON (W) LED PIN VOLTAGE (V) (VIN = 5 V, VL = 12 V, TAMB = 25°C, typical application circuit unless otherwise specified.) 0.7 0.6 0.5 20 15 10 R2 = R3 = 24 kW 0.4 3.0 3.5 4.0 4.5 5.0 5 5.5 5.0 5.5 Figure 10. FAULT Drive RDSON vs. VIN Supply 1.2 SWITCHING FREQUENCY (MHz) SWITCH RESISTANCE (W) 4.5 Figure 9. LED Channel Voltage vs. VIN Supply 1.0 0.5 3.0 3.5 4.0 4.5 5.0 1.1 1.0 0.9 0.8 5.5 3.0 3.5 4.0 4.5 5.0 VIN SUPPLY (V) VIN SUPPLY (V) Figure 11. Switch Resistance vs. VIN Supply Figure 12. Switching Frequency vs. VIN Supply 5.5 5 1200 1100 POWERDOWN DELAY (ms) SW CURRENT LIMIT (mA) 4.0 VIN SUPPLY (V) 1.5 1000 900 800 700 600 3.5 VIN SUPPLY (V) 2.0 0 3.0 3.0 3.5 4.0 4.5 5.0 4 3 2 1 0 5.5 3.0 3.5 4.0 4.5 5.0 VIN SUPPLY (V) VIN SUPPLY (V) Figure 13. Switching Current Limit vs. VIN Supply Figure 14. Powerdown Delay vs. VIN Supply http://onsemi.com 5 5.5 CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS (VIN = 5 V, VL = 12 V, TAMB = 25°C, typical application circuit unless otherwise specified.) 100 TOTAL LED CURRENT (%) 0.95 VHI 0.90 0.85 VLO 0.80 0.75 0.70 3.0 3.5 4.0 4.5 5.0 10 100 Hz 1 5.5 1 kHz 1 10 100 VIN SUPPLY (V) DUTY CYCLE (%) Figure 15. EN/PWM Threshold vs. VIN Supply Figure 16. PWM Duty Cycle vs. LED Current Figure 17. PWM Dimming 100 Hz Figure 18. PWM Dimming 1 kHz 200 MAX ILED PER CHANNEL (mA) EN/PWM THRESHOLD (V) 1.00 VOUT = 20 V 150 25 V 30 V 100 50 0 2 4 6 8 10 12 14 VL (V) Figure 19. Power−Up 4 x 10 LEDs, 50 mA per Channel Figure 20. Maximum LED Current vs. VL Supply http://onsemi.com 6 16 CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS 100 95 95 EFFICIENCY (%) 100 90 85 80 90 85 80 VOUT = 19 V VOUT = 24 V 75 75 70 4.5 4.7 4.9 5.1 5.3 70 5.5 8 10 12 14 INPUT VOLTAGE (V) INDUCTOR VOLTAGE (V) Figure 21. Efficiency vs. VIN (VIN = VL) Figure 22. Efficiency vs. VL (VIN = 5 V) 100 95 EFFICIENCY (%) EFFICIENCY (%) (VIN = 5 V, VL = 12 V, 20 mA per channel (80 mA total output current), TAMB = 25°C, typical application circuit unless otherwise specified.) 90 85 80 75 70 40 80 120 160 200 OUTPUT CURRENT (mA) Figure 23. Efficiency vs. Output Current (9−LED String) http://onsemi.com 7 240 16 CAT4106 Table 5. PIN DESCRIPTION TQFN−16 Name TSSOP−16 LED1 1 LED1 cathode terminal GND 2 Signal Ground reference FAULT 3 Open/Short LED Fault detection output (active−low) PGND 4 Power Ground Reference (DC/DC Power Switch) Function FB 5 Feedback reference (300 mV) for setting LED channel operating voltage SW 6 Internal power FET switch drain connection EN/PWM 7 Device Enable (active high) and PWM control input N.C. 8 Not connected VIN 9 Supply voltage for the device CTRL 10 LED channel operating voltage (lowest of all 4 channels) VFMIN 11 Comparator input for setting the LED string short−circuit voltage limit VFMAX 12 Comparator input for setting the LED string open−circuit voltage limit RSET 13 RSET resistor pin for setting the LED channel operating current LED4 14 LED4 cathode terminal LED3 15 LED3 cathode terminal LED2 16 LED2 cathode terminal TAB TAB Thermal pad (connect to GND and PGND) Pin Descriptions VIN is the supply pin for the device. The supply input current needed for normal operation is approximately 2 mA plus 3 times IRSET pin current. During intervals of PWM dimming, or whenever the converter is not switching, the supply current will decrease by around 1 mA. The voltage applied at VIN should be kept between 3 V and 5.5 V. A small ceramic bypass capacitor of 0.1 mF or greater is recommended to be in close proximity to the VIN pin. EN/PWM is the device Enable and PWM dimming control input for all LED channels. Guaranteed levels of logic high and logic low are set at 1.3 V and 0.4 V respectively. During normal PWM dimming, the entire device remains fully biased and only the LED channels are pulsed on/off. The device will only enter zero current shutdown mode after the EN/PWM is help low for at least 5 ms typically. This pin has an internal pull−down resistor of 200 kW. RSET is the voltage regulated control pin for sensing the desired programming current level to be applied on all LED channels. During normal operation, the RSET pin is kept at 1.2 V and accurately monitors the current level in the externally applied R1 resistor. The current transfer ratio from RSET pin current to LED pin current is 100. LED1 to LED4 provide the regulated current source for driving each of the LED strings with a tightly matched constant current. To ensure optimal performance, the bias voltage on the LED channels should be set at a nominal 0.6 V or higher. Each channel is capable of driving a current up to 175 mA. All channels immediately enter a high impedance mode whenever the EN/PWM is taken LOW. CTRL pin is a multiplexer output which selects the lowest operating voltage appearing on any of the four LED output drive channels. This control signal represents the cathode terminal voltage of the LED string with greatest forward voltage (VF). An external resistor network from CTRL to FB can be used to set the lowest operating voltage of each channel. External current loading of the CTRL pin is recommended to be less than 25 mA. FB is the voltage feedback control pin for the internal high power DC/DC converter. This pin has a high impedance input and its voltage remains accurately regulated to 0.3 V during normal steady state operation. SW pin is the drain terminal of the high voltage CMOS power switch which has a typical on−resistance of 1 W and is current limited to 1 A typically. An overvoltage protection circuit places the device in a soft−clamping low power mode if the voltage transients exceed 40 V. VFMIN pin uses a pair of external resistors (R6 & R7) to program the worst case, minimum LED string forward voltage (VFMIN) expected in the specific application. If, during power−up, any LED string enters full regulation before this programmed level is reached (VFMIN pin voltage < 1.2 V), the string will be considered to contain LEDs which are short−circuit and a fault condition will be http://onsemi.com 8 CAT4106 flagged. The VFMIN input circuitry consists of a comparator referenced to 1.2 V. A typical value for resistor R7 is around 20 kW. R6 can be calculated as follows: R6 + R7 ǒ A typical value for resistor R5 is 20 kW. R4 can be calculated as follows: Ǔ R4 + R5 V FMIN *1 1.2 V ǒ Ǔ V FMAX *1 1.2 V If this detection feature is not needed, the VFMAX pin must be tied to ground. FAULT is an open−drain, active−low, logic signal which becomes active during an LED short−circuit or open−circuit condition. The pin must be connected to a pull−up resistor of around 100 kW tied to VIN. The drive pull−down resistance (when active) is typically less than 100 W. The diagnostic sequence used to determine a fault condition is initiated when the device is first enabled. PGND pin is the source connection terminal of the high voltage CMOS power switch in the DC/DC converter. The inductor supply bypass capacitor should be connected in close proximity to the PGND pin. The return current from PGND should be connected to the PCB ground plane. GND is the ground reference pin for the device. All analog control voltages are referenced to this pin. In addition, all LED drive currents are conducted through the GND pin. TAB is the thermal pad connection of the package and should be connected to PCB ground plane. If this detection feature is not needed, the VFMIN pin must be tied to ground. VFMAX pin uses a pair of external resistors (R4 & R5) to program the worst case, maximum LED string forward voltage (VFMAX) expected in the specific application. If any LED string fails to become regulated before the programmed voltage is reached, the string will be considered to contain LEDs which are open−circuit and a fault condition will be flagged. When an open−circuit is flagged, the individual channel that causes the open−circuit is internally flagged and subsequently ignored. In the event that all channels are detected as being Open−LED, the Output Voltage (top LED Anode) will stabilize at the VFMAX programmed voltage. The VFMAX input circuitry consists of a comparator referenced to 1.2 V. Block Diagram L VL D R4 R5 SW 300 mV C3 R6 R7 LED Cluster N_Series M_Parallel VFMIN VFMAX FAULT OVP Controller Ctrl/Fault Detector mC Diagnostics CTRL 1A 1W 1 MHz PWM Controller R2 LED1 FB LED1 LED2 LED3 LED4 Supply VIN Shutdown Delay EN/DIM System EN/SD I1 PWM_DIM I2 I3 I4 Drive Control IRSETx100 0 − 175 mA 200 kW R3 GND RSET LEDn PGND R1 Figure 24. CAT4106 Simplified Functional Block Diagram http://onsemi.com 9 CAT4106 Device Operation In a typical application, the CAT4106 drives an LED array consisting of up to four separate strings. A single external resistor value is used to select the drive level in all output channels. Each channel provides a very well regulated and tightly matched bias current on all LED strings. An integrated DC/DC boost converter is used to generate the high voltage output required to power the LED strings. Up to a maximum of 6 W of LED power can be delivered when powered from a 12 V supply. To offer improved performance, the device also allows the user to set the operating voltage level on the output drive channels. A pair of external resistors is used to control the nominal channel voltage, during normal operation. The resulting output voltage (LED anodes) will be equal to the sum of the adjusted channel voltage plus the maximum forward voltage present on any string. The CAT4106 provides four tightly matched current sinks to accurately regulate LED current in each channel. Up to 175 mA per channel can be programmed by selecting a suitable value for the external R1 resistor (connected between RSET and GND pins). LED Detection The CAT4106 detects failure conditions related to the LED load, such as if one of the LED strings has been disconnected (Open−LED) or if one LED string has a lower LED pin voltage than expected (Short−LED). Either condition is flagged by turning on the open−drain output on the FAULT pin. The Open−LED detection is active in normal operation. The Short−LED detection is only active during power−up, just after the EN/PWM input goes from low to high. If in normal operation (LEDs are in regulation) a short−LED condition occurs, it will not be detected. LED Current Setting The CAT4106 provides four tightly matched current sinks to accurately regulate LED current in each channel. The LED current is set by the external resistor R1 connected between the RSET pin and ground. The following formula gives the relationship between the resistor value and the LED current per channel. R1 [ 103 Figure 25. Cold Power−Up Short−LED Detection 1.2 V LED current per channel Table 6. RESISTOR R1 AND LED CURRENT LED Current per Channel (mA) R1 (W) 10 12.4 k 20 6.19 k 30 4.12 k 50 2.49 k 100 1.24 k 150 820 Figure 26. Normal Operation Open−LED Detection The test condition in Figure 25 is with one LED pin shorted to the output (top LED anode). The test condition in Figure 26 is with one LED pin floating or disconnected. In both cases, the CAT4106 is set to drive 50 mA per channel. Setting VFMIN Level (Short−LED) Setting the Channel Voltage The VFMIN level represents the minimum level expected for the LED string voltage “window of operation”. This voltage setting is based on the number of series LEDs being used and the expected minimum forward voltage VF during normal operation. Example: Consider a string of 6 LEDs in series, with each LED having a VF range of 3.5 V ± 0.5 V. Since the minimum VF of each LED is 3.0 V the overall lowest expected string voltage would be 18 V. Any string voltage of less than 18 V is considered as a short−circuit fault in one or more of the series LEDs. Each LED channel typically requires less than 0.5 V of headroom for full load operation. The lowest channel operating voltage can be controlled and programmed via the external resistor network connected between, CTRL, FB and GND as shown in Figure 24. Lowest LED pin voltage + V FB R2 ) R3 R3 For most applications, a gain of 2x (R2 equals R3) is recommended. The CTRL output pin has optimal performance when loaded with around 15 mA, which equates to an R3 resistor value of 20 kW. http://onsemi.com 10 CAT4106 During PWM dimming, the recommended minimum pulse width interval (either High or Low) is 0.2 ms. The recommended maximum pulse width during PWM dimming is 2.5 ms, however this only applies to the Low pulse interval. Pulse durations extending past 2.5 ms may cause the device to enter full shutdown mode. The LED channel response time is much longer if the device has been in shutdown mode. For most applications, a maximum dimming resolution can be achieved with PWM clock frequencies in the range of 100 Hz to 2 kHz. Pulse width intervals of 1 ms, allows up to 1000:1 dimming ratio at 1 kHz PWM frequency. The external resistor R6 value needed to set a VFMIN level of 18 V is calculated as follows: R6 + R7 18 V ǒ1.2 * 1Ǔ V For R7 = 20 kW, R6 = 280 kW. Setting VFMAX Level (Open−LED) The VFMAX level represents the maximum level expected for the LED string voltage “window of operation”. This voltage setting is based on the number of series LEDs being used and the expected maximum VF during normal operation. Example: Consider a string of 6 LEDs in series, with each LED having a VF range of 3.5 V ± 0.5 V. Since the maximum VF of each LED is 4.0 V, the overall maximum expected string voltage would be 24 V. Any string voltage which appears greater than 24 V would be considered as containing an open−circuit in one or more of the series LEDs. The external resistor R4 value needed to set a VFMAX level of 24 V is calculated as follows: R4 + R5 One or Two LED String Applications The CAT4106 can be used to drive one or two strings of LEDs by connecting together some LED pins. Also for applications requiring LED current greater than 175 mA, LED channels can be tied together, assuming the supply is suitable to drive the load. Figure 27 shows a typical application for driving a single string of LEDs. The LED current is equal to four times the channel current. 24 V ǒ1.2 * 1Ǔ V D L VL C2 For R5 = 20 kW, R4 = 380 kW. In normal operation, the LED string which has the largest VF will be used to set the VCTRL/VFB voltage levels. If the largest string voltage tries to exceed VFMAX setting, it will no longer be allowed to control the voltage level of VCTRL/VFB (i.e. it will be ignored) and subsequently the next largest LED string voltage will then be used in the control loop. All remaining functional LED channels will continue to operate as normal. If a disconnected LED string is reconnected, the FAULT flag remains on and the channel disabled until the device has been re−enabled with the EN pin going from low to high. If all LED channels are detected as being open−circuit, then the boost converter will limit the output voltage to the VFMAX setting. This eliminates the need for an external protection zener. C3 VIN VIN C1 CAT4106 OFF... ON... DIM... R2 R1 R4 R6 R5 R7 SW VFMAX VFMIN EN/PWM RSET LED1 LED2 LED3 LED4 VCTRL FAULT FB GND PGND VIN R8 R3 LED Fault Detection (open drain pull−down) Figure 27. Application Circuit for One LED String Figure 28 shows a typical application for driving two strings of LEDs. The LED current is equal to two times the channel current. Enable and PWM Dimming Control D L VL EN/PWM input signal provides two independent functions. The first function is to enable and disable the entire device. The second function is to apply PWM dimming on the output channels while the chip remains fully enabled. Applying logic high on the EN/PWM input will power up the device. The device will continue to remain powered up, even in the presence of PWM signals being applied. To disable the device into complete system shutdown mode, a logic low must be applied to the EN/PWM input for typically 5 ms. The duty cycle applied at the EN/PWM is directly applied to all the output channels. Each time the input is taken low, all output channels will immediately be switched off and the channels will resume normal operation when the PWM is taken back high. The response time of the channels when switching ON or OFF is typically 0.2 ms. C2 C3 VIN VIN C1 R4 R6 R5 R7 SW VFMAX VFMIN CAT4106 OFF... ON... DIM... R2 R1 R3 EN/PWM RSET LED1 LED2 LED3 LED4 VCTRL FAULT FB GND PGND VIN R8 LED Fault Detection (open drain pull−down) Figure 28. Application Circuit for Two LED Strings http://onsemi.com 11 CAT4106 Application Information External Component Selection Recommended Layout The board layout should provide good thermal dissipation through the PCB. Multiple via can be used to connect the tab of the CAT4106 to a large ground plane underneath the package. Input capacitor C1 should be placed as close to the driver IC as possible. The RSET resistor (R1) and channel voltage setting resistor (R3) should have a Kelvin connection to the GND pin of the CAT4106. Capacitors The CAT4106 requires small ceramic capacitors of 1 mF on the VIN pin (C1), 4.7 mF on the inductor input (C2), and 10 mF on the output (C3). Under normal condition, a 4.7 mF input capacitor (C2) is sufficient. The voltage rating of each capacitor should be compatible with the maximum voltage applied. For the output, a 50 V rated capacitor (C3) is recommended in case the LED becomes disconnected (Open−LED condition). X5R and X7R capacitor types are ideal due to their stability across temperature range. Inductor A 47 mH inductor is recommended for most applications. In cases where the efficiency is critical, inductances with lower series resistance are preferred. Inductors with current rating of 1 A or higher are recommended for most applications. Coilcraft CR73−470 inductor rated at 1.08 A is recommended for most applications. Schottky Diode The current rating of the Schottky diode (D) must exceed the peak current flowing through it. A 1 A rated Schottky diode is recommended. The Schottky diode performance is rated in terms of its forward voltage at a given current. In order to achieve the best efficiency, this forward voltage should be as low as possible. The response time is also critical since the driver is operating at 1 MHz. NXP PMEG6010CEJ (60 V / 1 A rated) Schottky barrier rectifier is recommended for most applications. Figure 29. Recommended Layout for TQFN−16 http://onsemi.com 12 CAT4106 PACKAGE DIMENSIONS TQFN16, 4x4 CASE 510AE−01 ISSUE A A D DETAIL A E2 E PIN#1 ID PIN#1 INDEX AREA TOP VIEW SIDE VIEW SYMBOL MIN NOM MAX A 0.70 0.75 0.80 A1 0.00 0.02 0.05 A3 BOTTOM VIEW e b 0.20 REF b 0.25 0.30 0.35 D 3.90 4.00 4.10 D2 2.00 −−− 2.25 E 3.90 4.00 4.10 E2 2.00 −−− 2.25 e L D2 A1 L DETAIL A 0.65 BSC 0.45 −−− A 0.65 Notes: (1) All dimensions are in millimeters. (2) Complies with JEDEC MO-220. A1 A3 FRONT VIEW http://onsemi.com 13 CAT4106 PACKAGE DIMENSIONS TSSOP16, 4.4x5 EXPOSED PAD CASE 948AP−01 ISSUE A b X c Y E1 E L1 PIN#1 IDENTIFICATION e L θ1 TOP VIEW EXPOSED THERMAL PAD ZONE END VIEW BOTTOM VIEW X ± 0.076 D A2 SIDE VIEW SYMBOL A A1 A2 b c D E E1 e L L1 N P R S θ X Y MIN A A1 NOM MAX 1.10 0.15 0.95 0.30 0.20 5.10 6.50 4.50 0.05 0.85 0.19 0.13 4.90 6.30 4.30 Y ± 0.076 P R 0.65 BSC 1.00 REF 0.45 0.90 6.50 4.60 0.37 0.75 1.00 6.70 4.80 0.47 0º 8º S e LAND PATTERN Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC MO-153 variations ABT. 2.74 REF 2.74 REF http://onsemi.com 14 N CAT4106 Example of Ordering Information (Note 7) 4. 5. 6. 7. 8. 9. Prefix Device # Suffix CAT 4106 HV4 −G T2 Company ID (Optional) Product Number 4106 Package HV4: TQFN 16−Pad YP: TSSOP 16−Lead (Note 6) YP: Exposed Thermal Pad Lead Finish G: NiPdAu Blank: Matte−Tin Tape & Reel (Note 9) T: Tape & Reel 2: 2,000 / Reel All packages are RoHS−compliant (Lead−free, Halogen−free). The standard plated finish is NiPdAu. TSSOP only available in Matte−Tin plated finish. The device used in the above example is a CAT4106HV4−GT2 (TQFN, NiPdAu, Tape & Reel, 2,000/Reel). For additional temperature options, please contact your nearest ON Semiconductor Sales office. 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. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada Email: [email protected] N. American Technical Support: 800−282−9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5773−3850 http://onsemi.com 15 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative CAT4106/D