CAT4106 6W Quad Channel DC/DC LED Driver with Diagnostics DESCRIPTION FEATURES 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 RoHS-compliant 16-lead TQFN 4 x 4 mm and TSSOP packages 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. APPLICATIONS LCD Backlight Lighting Automotive and General Purpose Lighting 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). ORDERING INFORMATION Part Number Package Quantity per Reel CAT4106HV4-GT2 TQFN-16 (1) CAT4106YP-T2 Notes: (1) (2) TSSOP-16 (2) Package Marking 2,000 CDAL 2,000 4106Y The device is available in a 16-lead TQFN 4 mm x 4 mm and TSSOP with exposed pad packages. NiPdAu Plated Finish (RoHS-compliant) Matte-Tin Plated Finish (RoHS-compliant). For Ordering Information details, see page 16. PIN CONFIGURATION TSSOP 16-Lead (Top View) LED1 GND FAULT PGND FB SW EN/PWM NC 1 16 2 15 3 14 4 5 6 TAB is GND 13 12 11 7 10 8 9 LED2 LED3 LED4 RSET VFMAX VFMIN CTRL VIN TYPICAL APPLICATION CIRCUIT L VL 3 V to 24 V 47 µH C2 10 µF/50 V VIN TQFN 16-Lead (Top View) PGND RSET FAULT LED4 2 LED3 GND LED2 1 16 15 14 13 3 VIN 7 8 FB SW EN/PW NC © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice R5 R7 VFMAX CAT4106 EN/PWM R2 20 kΩ LED1 LED2 LED3 LED4 RSET CTRL R3 R1 9 VIN 6 R6 OFF... ON... DIM 10 CTRL 5 R4 VFMIN 11 VFMIN 4 SW 1 µF 12 VFMAX TAB is GND C3 4.7µF 3 V to 5.5 V C1 LED1 D 1 20 kΩ FB GND PGND VIN FAULT R8 LED Fault Detection (open drain pull-down) Doc. No. MD-5037, Rev. A CAT4106 ABSOLUTE MAXIMUM RATINGS (1) Parameters VIN, RSET, EN/PWM, CTRL, FB, ¯¯¯¯¯¯ FAULT Ratings Units -0.3V to 6 V VFMIN, VFMAX -0.3V to 6 V LED1, LED2, LED3, LED4 -0.3V to 25 V 50 V Storage Temperature Range -65 to +160 °C Junction Temperature Range -40 to +150 °C 300 °C Range Units SW (internally clamped to 40 V) Lead Temperature RECOMMENDED OPERATING CONDITIONS Parameter 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 Typical application circuit with external components is shown on page 1. RECOMMENDED EN/PWM TIMING For 3.0 ≤ VIN ≤ 5.5V, over full ambient temperature range -40 to +85ºC. Symbol Name TLEDSETUP Conditions Min Typ Max Units LED setup time from shutdown 10 40 100 μs TLO EN/PWM low time 0.2 2000 μs THI EN/PWM high time 0.2 8 ms TPWRDWN EN/PWM low time to shutdown delay TLEDSET LED current settling time TLEDSETUP ILED = 100 mA THI TLO μs 0.2 μs TPWRDWN EN/PWM SHUTDOWN DIMMING 100% BRIGHTNESS POWERDOWN SHUTDOWN LED CURRENT DEVICE QUIESCENT CURRENT Figure 3. CAT4106 EN/PWM Timing Notes: (1) Stresses above 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 conditions outside of those listed in the operational sections of this specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability. Doc. No. MD-5037, Rev. A 2 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 ELECTRICAL OPERATING CHARACTERISTICS VIN = 5 V, VL (inductor drive voltage) = 12 V, TAMB = 25°C (over recommended operating conditions unless specified otherwise) Symbol Description Conditions Switching Not Switching Switching Not Switching VEN = 0V Min (ILED = 30 mA) (ILED = 30 mA) (ILED = 60 mA) (ILED = 60 mA) IQ VIN Operating Current ISD VIN input shutdown Current 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 0.4 100 Typ 2.5 2.0 3.4 2.9 0.8 0.7 200 Max 3.5 3.0 4.4 3.9 1 Units 1.3 V V kΩ 300 mA µA 2.0 V Thermal Shutdown Threshold 150 °C THYS Thermal Hysteresis 20 °C VRSET RSET regulation voltage 10 μA < IRSET < 2 mA. ILED/IRSET RSET to LED Current gain ratio 30 mA LED current 100 VDO LED Channel Dropout Voltage ILED = 175 mA 0.5 ΔILED LED Channel Matching 0.5 V < VLED < 5 V ILED-OFF LED Channel leakage Channel is Off VVFMAX O/C Detect voltage threshold 1.15 VVFMIN S/C Detect voltage threshold VCTRL ICTRL CTRL pin voltage accuracy CTRL pin maximum load I¯¯¯¯¯¯ FAULT Pull-down Drive Current Open Drain Leakage Current VFB IFB FB Pin control voltage FB pin input leakage current 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 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice 1.17 V V % 1 µA 1.20 1.25 V 1.15 1.20 1.25 V Offset to Lowest LED output - 0.1 25 0 + 0.1 V µA ¯¯¯¯¯¯ FAULT is Active (0.1 V bias) ¯¯¯¯¯¯ FAULT is Inactive Normal switching mode regulation 1 2 3 ±1 1.23 +5 ISW = 500 mA Prior to Current Limiting Prior to Pulse-Skipping VSW = 20 V Enters Low Power mode -5 1.20 1 mA µA 285 300 315 1 mV µA 0.7 0.8 1.0 1.0 1.0 96 5 1.3 MHz A Ω % % µA V 5 40 Doc. No. MD-5037, Rev. A CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS VIN = 5 V, VL = 12 V, TAMB = 25ºC, typical application circuit unless otherwise specified. Quiescent Current vs. RSET Current RSET Voltage vs. VIN Supply 1.30 6 RSET VOLTAGE [V] QUIESCENT CURRENT [mA] 8 switching 4 not switching 2 0 1.25 1.20 1.15 1.10 0.0 0.5 1.0 1.5 2.0 3.0 3.5 RSET CURRENT [mA] 1.25 120 1.20 100 GAIN RSET VOLTAGE [V] 140 1.15 80 1.10 60 50 100 20 150 60 100 140 180 LED Channel Current vs. VIN Supply LED Channel Current vs. LED Pin Voltage 200 200 175 175 150 150 LED CURRENT [mA] LED CURRENT [mA] 5.5 LED CURRENT [mA] TEMPERATURE [ºC] 125 100 75 50 25 0 125 100 75 50 25 0 0.0 0.2 0.4 0.6 0.8 1.0 3.0 LED PIN VOLTAGE [V] Doc. No. MD-5037, Rev. A 5.0 ILED/IRSET Gain vs. LED Current 1.30 0 4.5 VIN SUPPLY [V] RSET Voltage vs. Temperature -50 4.0 3.5 4.0 4.5 5.0 5.5 VIN SUPPLY [V] 4 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS VIN = 5 V, VL = 12 V, TAMB = 25ºC, typical application circuit unless otherwise specified. FAULT Drive RDSON vs. VIN Supply 0.9 30 0.8 25 FAULT DRIVE RDSON [Ω] LED PIN VOLTAGE [V] LED Channel Voltage vs. VIN Supply 0.7 0.6 0.5 R2 = R3 = 24kΩ 20 15 10 5 0.4 3.0 3.5 4.0 4.5 5.0 3.0 5.5 3.5 VIN SUPPLY [V] 2.0 5.0 5.5 1.2 SWITCHING FREQUENCY [MHz] SWITCH RESISTANCE [Ω] 4.5 Switching Frequency vs. VIN Supply Switch Resistance vs. VIN Supply 1.5 1.0 0.5 0.0 3.0 3.5 4.0 4.5 5.0 5.5 1.1 1.0 0.9 0.8 3.0 3.5 4.0 4.5 5.0 5.5 VIN SUPPLY [V] VIN SUPPLY [V] Switching Current Limit vs. VIN Supply Powerdown Delay vs. VIN Supply 5 1200 1100 POWERDOWN DELAY [ms] SW CURRENT LIMIT [mA] 4.0 VIN SUPPLY [V] 1000 900 800 700 600 3.0 3.5 4.0 4.5 5.0 5.5 3 2 1 0 3.0 VIN SUPPLY[V] © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice 4 3.5 4.0 4.5 5.0 5.5 VIN SUPPLY [V] 5 Doc. No. MD-5037, Rev. A CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS VIN = 5 V, VL = 12 V, TAMB = 25ºC, typical application circuit unless otherwise specified. EN/PWM Threshold vs. VIN Supply PWM Duty Cycle vs. LED Current 100 0.95 0.90 VHI TOTAL LED CURRENT [%] EN/PWM THRESHOLD [V] 1.00 VLO 0.85 0.80 0.75 0.70 3.0 3.5 4.0 4.5 5.0 100Hz 10 1kHz 1 5.5 1 10 VIN SUPPLY [V] 100 DUTY CYCLE [%] PWM Dimming 1 kHz PWM Dimming 100 Hz Power-Up 4 x 10 LEDs, 50 mA per Channel Maximum LED Current vs. VL Supply MAX ILED PER CHANNEL [mA] 200 VOUT = 20V 150 25V 100 50 30V 0 2 4 6 8 10 12 14 16 VL [V] Doc. No. MD-5037, Rev. A 6 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 TYPICAL ELECTRICAL OPERATING CHARACTERISTICS VIN = 5 V, VL = 12 V, 20mA per channel (80mA total output current), TAMB = 25ºC, typical application circuit unless otherwise specified. Efficiency vs. VL (VIN = 5V) 100 100 95 95 EFFICIENCY [%] EFFICIENCY [%] Efficiency vs. VIN (VIN = VL) 90 85 80 VOUT = 19V 75 90 85 80 VOUT = 24V 75 70 70 4.5 4.7 4.9 5.1 5.3 5.5 8 INPUT VOLTAGE [V] 10 12 14 16 INDUCTOR VOLTAGE [V] Efficiency vs. Output Current (9-LED string) 100 EFFICIENCY [%] 95 90 85 80 75 70 40 80 120 160 200 240 OUTPUT CURRENT [mA] © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice 7 Doc. No. MD-5037, Rev. A CAT4106 PIN DESCRIPTION Name TQFN-16 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) 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 LED3 14 LED3 cathode terminal LED3 15 LED3 cathode terminal LED4 16 LED4 cathode terminal TAB TAB Function 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 μF or greater is recommended to be in close proximity to the VIN pin. 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 μA. 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 kΩ. 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 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. Doc. No. MD-5037, Rev. A 8 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 SW pin is the drain terminal of the high voltage CMOS power switch which has a typical on-resistance of 1 Ω 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. VFMAX programmed voltage. The VFMAX input circuitry consists of a comparator referenced to 1.2 V. A typical value for resistor R5 is 20 kΩ. R4 can be calculated as follows: 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 flagged. The VFMIN input circuitry consists of a comparator referenced to 1.2 V. A typical value for resistor R7 is around 20 kΩ. R6 can be calculated as follows: ⎛V ⎞ R4 = R5 × ⎜⎜ 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 opencircuit condition. The pin must be connected to a pullup resistor of around 100 kΩ tied to VIN. The drive pull-down resistance (when active) is typically less than 100 Ω. The diagnostic sequence used to determine a fault condition is initiated when the device is first enabled. ⎛V ⎞ R6 = R7 × ⎜⎜ FMIN − 1⎟⎟ ⎝ 1 .2 V ⎠ If this detection feature is not needed, the VFMIN pin must be tied to ground. 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. 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 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice 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. 9 Doc. No. MD-5037, Rev. A CAT4106 BLOCK DIAGRAM L VL D C3 R4 R6 R5 SW R7 VFMAX VFMIN FAULT OVP Controller 300mV LED Cluster N_Series M_Parallel µC Diagnostics Ctrl/Fault Detector CTRL 1A 1Ω 1MHz PWM Controller R2 LED1 FB VIN LEDn LED1 Supply Shutdown Delay EN/DIM LED2 System EN/SD LED3 LED4 I1 PWM_DIM I2 I3 I4 0 - 175 mA Drive Control IRSETx100 200 kΩ R3 RSET GND PGND R1 Figure 4. CAT4106 Simplified Functional Block Diagram DEVICE OPERATION external R1 resistor (connected between RSET and GND pins). 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. 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 feedback pin (FB) and ground. The following formula gives the relationship between the resistor value and the LED current per channel. 1 .2 V R1 ≈ 103 × LED current per channel 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. LED current per channel (mA) 10 20 30 50 100 150 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 Doc. No. MD-5037, Rev. A R1 (Ω) 12.4 k 6.19 k 4.12 k 2.49 k 1.24 k 820 Table 1. Resistor R1 and LED current 10 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 SETTING THE CHANNEL VOLTAGE 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 4. Lowest LED pin voltage = VFB × The test condition in Figure 5 is with one LED pin shorted to the output (top LED anode). The test condition in Figure 6 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) 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. 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 μA, which equates to an R3 resistor value of 20 kΩ. 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. 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 opendrain 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. The external resistor R6 value needed to set a VFMIN level of 18 V is calculated as follows: ⎛ 18 V ⎞ R6 = R7 × ⎜⎜ − 1⎟⎟ ⎝ 1. 2 V ⎠ For R7 = 20 kΩ, R6 = 280 kΩ. 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: Figure 5. Cold Power-Up Short-LED Detection ⎛ 24 V ⎞ R4 = R5 × ⎜⎜ − 1⎟⎟ ⎝ 1 .2 V ⎠ For R5 = 20 kΩ, R4 = 380 kΩ. 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 Figure 6. Normal Operation Open-LED Detection © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice 11 Doc. No. MD-5037, Rev. A CAT4106 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 7 shows a typical application for driving a single string of LEDs. The LED current is equal to four times the channel current. 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. ENABLE AND PWM DIMMING CONTROL 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. L VL D C2 C3 VIN SW VIN R4 R6 R5 R7 VFMAX VFMIN C1 CAT4106 OFF... ON... DIM... EN/PWM LED1 LED2 LED3 LED4 RSET R2 VCTRL FB 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 µs. R1 GND PGND VIN FAULT R8 R3 LED Fault Detection (open drain pull-down) Figure 7. Application Circuit for One LED String Figure 8 shows a typical application for driving two strings of LEDs. The LED current is equal to two times the channel current. During PWM dimming, the recommended minimum pulse width interval (either High or Low) is 0.2 µs. 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. L VL D C2 C3 VIN SW VIN R6 R5 R7 VFMAX VFMIN C1 CAT4106 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 μs, allows up to 1000:1 dimming ratio at 1 kHz PWM frequency. R4 OFF... ON... DIM... EN/PWM LED1 LED2 LED3 LED4 RSET R2 VCTRL FB R1 R3 GND PGND VIN FAULT R8 LED Fault Detection (open drain pull-down) Figure 8. Application Circuit for Two LED Strings Doc. No. MD-5037, Rev. A 12 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 APPLICATION INFORMATION 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. External Component Selection Capacitors The CAT4106 requires small ceramic capacitors of 1 µF on the VIN pin (C1), 4.7 μF on the inductor input (C2), and 10 µF on the output (C3). Under normal condition, a 4.7 µF 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. 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. Inductor A 47 µH 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 1A 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. © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice Figure 9. Recommended Layout for TQFN-16 13 Doc. No. MD-5037, Rev. A CAT4106 PACKAGE OUTLINE DRAWINGS TQFN 16-Pad 4 x 4 mm (HV4) (1) (2) A D DETAIL A E2 E PIN#1 ID PIN#1 INDEX AREA TOP VIEW SYMBOL MIN SIDE VIEW NOM A 0.70 0.75 0.80 0.00 0.02 0.05 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 BOTTOM VIEW MAX A1 A3 D2 A1 L DETAIL A A 0.65 BSC 0.45 – 0.65 A1 A3 FRONT VIEW For current Tape and Reel information, download the PDF file from: http://www.catsemi.com/documents/tapeandreel.pdf. Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC standard MO-220 Doc. No. MD-5037, Rev. A 14 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 TSSOP 16-Lead Exposed Thermal Pad 4.4 mm (YP) b (1) (2) X c Y E1 E L L1 PIN#1 IDENTIFICATION e θ1 TOP VIEW EXPOSED THERMAL PAD ZONE END VIEW BOTTOM VIEW D A2 A A1 A2 b c D E E1 e L L1 N P R S θ1 X Y MIN X ± 0.076 A1 SIDE VIEW SYMBOL A 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° 0.75 1.00 6.70 4.80 0.47 8° 2.74 REF 2.74 REF Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC standard MO-153 variations ABT © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice S e N LAND PATTERN For current Tape and Reel information, download the PDF file from: http://www.catsemi.com/documents/tapeandreel.pdf. 15 Doc. No. MD-5037, Rev. A CAT4106 EXAMPLE OF ORDERING INFORMATION (1) Prefix Device # Suffix CAT 4106 HV4 Company ID Product Number Package HV4: TQFN 16-Pad (3) YP: TSSOP 16-Lead Exposed Thermal Pad 4106 - G T2 Lead Finish G: NiPdAu Blank: Matte-Tin Tape & Reel T: Tape & Reel 2: 2,000/Reel For Product Top Mark Codes, click here: http://www.catsemi.com/techsupport/producttopmark.asp Notes: (1) All packages are RoHS-compliant (Lead-free, Halogen-free). (2) The standard plated finish is NiPdAu. (3) TSSOP only available in Matte-Tin plated finish. (4) The device used in the above example is a CAT4106HV4-GT2 (TQFN, NiPdAu, Tape & Reel, 2,000/Reel). (5) For additional temperature options, please contact your nearest ON Semiconductor Sales office. Doc. No. MD-5037, Rev. A 16 © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice CAT4106 REVISION HISTORY Date 17-Feb-09 Revision A Description Initial Issue 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] Doc. No. MD-5037 Rev. A 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 17 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative © 2009 SCILLC. All rights reserved. Characteristics subject to change without notice