CAT3647

CAT3647 3-Channel Ultra High Efficiency Quad-Mode) LED Driver with 32 Dimming Levels Description http://onsemi.com The CAT3647 is a high efficiency quad−mode fractional charge pump that can drive up to three LEDs programmable by a one wire digital interface. The inclusion of a 1.33x fractional charge pump mode increases device efficiency by up to 10% over traditional 1.5x charge pumps with no added external capacitors. Low noise input ripple is achieved by operating at a constant switching frequency which allows the use of small external ceramic capacitors. The multi−fractional charge pump supports a wide range of input voltages from 2.4 V to 5.5 V. The EN/DIM logic input functions as a chip enable and a digital dimming interface for setting the current in all the LED channels. The 1−wire pulse−dimming interface supports 32 linear steps from full−scale down to zero current. The device is available in the tiny 16−pad TQFN 3 mm x 3 mm package with a max height of 0.8 mm. ON Semiconductor’s Quad−Mode® 1.33x, charge pump switching architecture is patented. Features TQFN−16 HV3 SUFFIX CASE 510AD PIN CONNECTIONS LED1 GND NC NC LED2 LED3 NC RSET 1 C2− C2+ C1− C1+ VOUT NC • • • • • • • • • • • • High Efficiency 1.33x Charge Pump Quad−mode Charge Pump: 1x, 1.33x, 1.5x, 2x Drives up to 3 LEDs at 30 mA Each 1−wire EZDimt 32 Linear Steps Power Efficiency up to 92% Low Noise Input Ripple in All Modes “Zero” Current Shutdown Mode Soft Start and Current Limiting Short Circuit Protection Thermal Shutdown Protection 16−pad TQFN Package These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant LCD Display Backlight Cellular Phones Digital Still Cameras Handheld Devices MARKING DIAGRAM JAAP AXXX YWW JAAP = CAT3647HV3−GT2 A = Assembly Location XXX = Last Three Digits of Assembly Lot Number Y = Production Year (Last Digit) WW = Production Week (Two Digits) Applications ORDERING INFORMATION Device CAT3647HV3−GT2 (Note 1) Package TQFN−16 (Pb−Free) Shipping 2,000/ Tape & Reel • • • • 1. NiPdAu Plated Finish (RoHS−compliant). EN/DIM (Top View) © Semiconductor Components Industries, LLC, 2010 May, 2010 − Rev. 2 1 Publication Order Number: CAT3647/D VIN CAT3647 1 mF C1+ CIN 1 mF VIN CAT3647 EN/DIM RSET GND LED1 LED2 LED3 C1− C2+ 1 mF C2− VOUT VIN 2.4 V to 5.5 V VOUT COUT 1 mF 1−Wire EZDimt Programming 3.74 kΩ 20 mA Figure 1. Typical Application Circuit Table 1. ABSOLUTE MAXIMUM RATINGS Parameter VIN, LEDx, C1±, C2±, EN/DIM, RSET voltage VOUT voltage Storage Temperature Range Junction Temperature Range Rating 6 7 −65 to +160 −40 to +150 Unit V V °C °C 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 VIN Ambient Temperature Range ILED per LED pin LED Forward Voltage Range NOTE: Typical application circuit with external components is shown above. Rating 2.5 to 5.5 −40 to +85 up to 30 1.3 to 4.3 Unit V °C mA V http://onsemi.com 2 CAT3647 Table 3. ELECTRICAL OPERATING CHARACTERISTICS (over recommended operating conditions unless specified otherwise) VIN = 3.6 V, EN = High, TAMB = 25°C Symbol IQ Quiescent Current Name Conditions 1x mode, excluding load 1.33x mode, excluding load 1.5x mode, excluding load 2x mode, excluding load VEN = 0 V RSET = 3.74 kW RSET = 7.50 kW ILED-ACC ILED-DEV VRSET ROUT LED Current Accuracy LED Channel Matching RSET Regulated Voltage Output Resistance (open loop) 1x mode 1.33x mode, VIN = 3 V 1.5x mode, VIN = 2.7 V 2x mode, VIN = 2.4 V 1.33x and 2x mode 1.5x mode VOUT < 0.5 V VOUT > 1 V, 1x mode 0.8 1 (ILEDAVG – INOMINAL) / INOMINAL RSET = 4.99 kW (ILED - ILEDAVG) / ILEDAVG 0.58 20 10 ±2 ±1.5 0.6 0.8 5 5 10 1 1.3 50 250 130 400 120 100 1.3 0.4 150 20 1.6 1.8 2.0 1.3 1.6 0.62 % % V W Min Typ 1.0 1.7 2.2 2.4 1 Max Units mA IQSHDN ILED-ACC Shutdown Current LED Current Setting mA mA FOSC ISC_MAX IIN_MAX LEDTH VHYS TDF REN/DIM VHI VLO TSD THYS VUVLO Charge Pump Frequency Output short circuit Current Limit Input Current Limit 1x to 1.33x or 1.33x to 1.5x or 1.5x to 2x Transition Thresholds at any LED pin 1x Mode Transition Hysteresis Mode Transition Filter Delay EN/DIM Pin − Internal Pull-down Resistor − Logic High Level − Logic Low Level Thermal Shutdown Thermal Hysteresis Undervoltage lockout (UVLO) threshold MHz mA mA mV mV ms kW V V °C °C V http://onsemi.com 3 CAT3647 Table 4. RECOMMENDED EN/DIM TIMING (For 2.4 V ≤ VIN ≤ 5.5 V, over full ambient temperature range -40°C to +85°C.) Symbol TLO THI TPWRDWN TLED Name EN/DIM program low time EN/DIM program high time EN/DIM low time to shutdown LED current settling time THI EN/DIM TLO TLED 100% LED Current 97% 93% 32 Levels 3% 0% 100% TPWRDWN Conditions Min 0.2 0.2 1.5 40 Typ Max 100 Units ms ms ms ms Shutdown Shutdown Figure 2. EN/DIM Digital Dimming Timing Diagram LED Current Setting The full scale LED current is set by the external resistor connected between the RSET pin and ground. Table 5 lists standard resistor values for several LED current settings. Table 5. RESISTOR RSET AND LED CURRENT Full Scale LED Current [mA] 2 5 10 15 20 25 30 RSET [kW] 37.4 14.7 7.50 4.99 3.74 3.00 2.49 http://onsemi.com 4 CAT3647 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 60 mA (3 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) 100 90 1x EFFICIENCY (%) EFFICIENCY (%) 80 70 60 50 40 2x 80 70 60 50 40 1.33x VF = 3.3 V 100 1.33x 1.5x 90 VF = 3.3 V 1x 4.5 4.0 3.5 3.0 2.5 2.0 4.2 4.0 3.8 3.6 3.4 3.2 3.0 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Figure 3. Efficiency vs. Input Voltage 4 QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) VF = 3.3 V 3 4 Figure 4. Efficiency vs. Li−Ion Voltage 3 2x 1.5x 1.33x 1x 2 2 1 LEDs Off 0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1 0 −40 0 40 TEMPERATURE (°C) 80 120 INPUT VOLTAGE (V) Figure 5. Quiescent Current vs. Input Voltage 10 LED CURRENT VARIATION (%) 6 4 2 0 −2 −4 −6 −8 −10 LED CURRENT VARIATION (%) 8 VF = 3.3 V 10 8 6 4 2 0 −2 −4 −6 Figure 6. Quiescent Current vs. Temperature VF = 3.3 V 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 −8 −10 −40 0 40 TEMPERATURE (°C) 80 120 INPUT VOLTAGE (V) Figure 7. LED Current Change vs. Input Voltage Figure 8. LED Current Change vs. Temperature http://onsemi.com 5 CAT3647 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 60 mA (3 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) 1.3 SWITCHING FREQUENCY (MHz) OUTPUT RESISTANCE (W) 1.2 1.1 1.0 0.9 0.8 0.7 −40 0 40 TEMPERATURE (°C) 80 120 1.33x, 2x Mode 12 10 8 6 4 2 0 2x 1.5x Mode 1.5x 1.33x 1x 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Figure 9. Switching Frequency vs. Temperature Figure 10. Output Resistance vs. Input Voltage Figure 11. Power Up in 1x Mode Figure 12. Power Up in 1.33x Mode Figure 13. Power Up in 1.5x Mode Figure 14. Power Up in 2x Mode http://onsemi.com 6 CAT3647 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 60 mA (3 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) Figure 15. Power Up Delay (1x Mode) Figure 16. Power Down Delay (1x Mode) Figure 17. Operating Waveforms in 1x Mode Figure 18. Switching Waveforms in 1.33x Mode Figure 19. Switching Waveforms in 1.5x Mode Figure 20. Switching Waveforms in 2x Mode http://onsemi.com 7 CAT3647 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 60 mA (3 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) 4.0 3.5 OUTPUT VOLTAGE (V) 3.0 2.5 2.0 1.5 1.0 0.5 0 0 100 200 300 400 0 0 50 100 150 200 250 300 1x Mode LED CURRENT (mA) OUTPUT CURRENT (mA) 30 40 20 10 LED PIN VOLTAGE (mV) Figure 21. Foldback Current Limit Figure 22. LED Current vs. LED Pin Voltage Figure 23. Dimming Waveform http://onsemi.com 8 CAT3647 Table 6. PIN DESCRIPTION Name LED1 LED2 LED3 RSET EN/DIM VOUT VIN C1+ C1C2+ C2GND NC GND LED1 cathode terminal. LED2 cathode terminal. LED3 cathode terminal. Connect resistor RSET to set the LED current. Device enable (active high) and Dimming Control. Charge pump output connected to the LED anodes. Charge pump input, connect to battery or supply. Bucket capacitor 1 Positive terminal Bucket capacitor 1 Negative terminal Bucket capacitor 2 Positive terminal Bucket capacitor 2 Negative terminal Ground Reference Not connected inside package. Connect to GND on the PCB. Function Pin Function VIN is the supply pin for the charge pump. A small 1 mF ceramic bypass capacitor is required between the VIN pin and ground near the device. The operating input voltage range is from 2.5 V to 5.5 V. Whenever the input supply falls below the under-voltage threshold (1.8 V), all the LED channels are disabled and the device enters shutdown mode. EN/DIM is the enable and one wire dimming input for all LED channels. Levels of logic high and logic low are set at 1.3 V and 0.4 V respectively. When EN/DIM is initially taken high, the device becomes enabled and all LED currents are set to the full scale according to the resistor RSET. To place the device into “zero current” shutdown mode, the EN/DIM pin must be held low for at least 1.5 ms. VOUT is the charge pump output that is connected to the LED anodes. A small 1 mF ceramic bypass capacitor is required between the VOUT pin and ground near the device. GND is the ground reference for the charge pump. The pin must be connected to the ground plane on the PCB. C1+, C1- are connected to each side of the ceramic bucket capacitor C1. C2+, C2- are connected to each side of the ceramic bucket capacitor C2. LED1, LED2, LED3 provide the internal regulated current sources for each of the LED cathodes. These pins enter high-impedance zero current state whenever the device is placed in shutdown mode. TAB is the exposed pad underneath the package. For best thermal performance, the tab should be soldered to the PCB and connected to the ground plane. RSET is connected to the resistor (RSET) to set the full scale current for the LEDs. The voltage at this pin regulated to 0.6 V. The ground side of the external resistor should be star connected back to the GND of the PCB. In shutdown mode, RSET becomes high impedance. http://onsemi.com 9 CAT3647 Block Diagram C1+ C1− C2− C2+ VIN 1x mode (LDO) 1.33x, 1.5x, 2x Charge Pump VOUT Mode Control EN/DIM 100 kΩ Serial Interface Reference Voltage 1, 1.3 MHz Oscillator LED1 LED2 LED3 Registers Current Setting DAC LED Channel Current Regulators RSET GND Figure 24. CAT3647 Functional Block Diagram Basic Operation At power-up, the CAT3647 starts operating in 1x mode where the output will be approximately equal to the input supply voltage (less any internal voltage losses). If the output voltage is sufficient to regulate all LED currents, the device remains in 1x operating mode. If the input voltage is insufficient or falls to a level where the regulated currents cannot be maintained, the device automatically switches into 1.33x mode (after a fixed delay time of about 120 ms). In 1.33x mode, the output voltage is approximately equal to 1.33 times the input supply voltage (less any internal voltage losses). This sequence repeats in the 1.33x and 1.5x mode until the driver enters the 2x mode. In 1.5x mode, the output voltage is approximately equal to 1.5 times the input supply voltage. While in 2x mode, the output is approximately equal to 2 times the input supply voltage. If the device detects a sufficient input voltage is present to drive all LED currents in 1x mode, it will change automatically back to 1x mode. This only applies for changing back to the 1x mode. The difference between the input voltage when exiting 1x mode and returning to 1x mode is called the 1x mode transition hysteresis (VHYS) and is about 400 mV. http://onsemi.com 10 CAT3647 LED Current Selection After power-up, the LED current is set by the external resistor (RSET) value and the number of pulses (n) on the EN/DIM input as follows: LED current + 125 0.6 V R SET 31 * n 31 Table 7. DIMMING LEVELS Full Scale Current in % 100 97 94 90 87 84 81 77 74 71 68 65 61 58 55 52 48 45 42 39 35 32 29 26 23 19 16 13 10 6 3 0 100 Dimming Pulses [n] 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 The full scale current is calculated from the above formula with n equal to zero. The EN/DIM pin has two primary functions. One function enables and disables the device. The other function is LED current dimming with 32 different levels by pulsing the input signal, as shown on Figure 25. On each consecutive pulse rising edge, the LED current is decreased by about 3.2% (1/31th of the full scale value). After 30 pulses, the LED current is 3.2% of the full scale current. On the 31st pulse, the current drops to zero, and then goes back to full scale on the following pulse. Each pulse width should be between 200 ns and 100 ms. Pulses faster than the minimum TLO may be ignored and filtered by the device. Pulses longer than the maximum TLO may shutdown the device. By pulsing the EN/DIM signal at high frequency, the LED current can quickly be set to zero. The LED driver enters a “zero current” shutdown mode if EN/DIM is held low for 1.5 ms or more. The dimming level is set by the number of pulses on the EN/DIM after the power-up, as shown in Table 7. THI EN/DIM TLO TLED 100% LED Current Shutdown 97% 93% 32 Levels 3% 0% 100% Shutdown TPWRDWN Figure 25. EN/DIM Digital Dimming Timing Diagram http://onsemi.com 11 CAT3647 Unused LED Channels LED Selection For applications not requiring all the channels, it is recommended the unused LED pins be tied directly to VOUT (see Figure 26). 1 mF 1 mF VIN 2.4 V to 5.5 V CIN 1 mF C1+ VIN C1− C2+ C2− VOUT VOUT COUT 1 mF LEDs with forward voltages (VF) ranging from 1.3 V to 4.3 V may be used. Selecting LEDs with lower VF is recommended in order to improve the efficiency by keeping the driver in 1x mode longer as the battery voltage decreases. For example, if a white LED with a VF of 3.3 V is selected over one with VF of 3.5 V, the driver will stay in 1x mode for lower supply voltage of 0.2 V. This helps improve the efficiency and extends battery life. External Components CAT3647 EN/DIM RSET GND LED1 LED2 LED3 1−Wire EZDimt Programming 3.74 kΩ 20 mA The driver requires four external 1 mF ceramic capacitors for decoupling input, output, and for the charge pump. Both capacitors type X5R and X7R are recommended for the LED driver application. In all charge pump modes, the input current ripple is kept very low by design and an input bypass capacitor of 1 mF is sufficient. In 1x mode, the device operates in linear mode and does not introduce switching noise back onto the supply. Recommended Layout Figure 26. Application with 2 LEDs Protection Mode If an LED is disconnected, the driver senses that and automatically ignores that channel. When all LEDs are disconnected, the driver goes to 1x mode where the output is equal to the input voltage. As soon as the output exceeds about 6 V, the driver resets itself and re-evaluates the mode. If the die temperature exceeds +150°C, the driver will enter a thermal protection shutdown mode. When the device temperature drops by about 20°C, the device will resume normal operation. In charge pump mode, the driver switches internally at a high frequency. It is recommended to minimize trace length to all four capacitors. A ground plane should cover the area under the driver IC as well as the bypass capacitors. Short connection to ground on capacitors CIN and COUT can be implemented with the use of multiple via. A copper area matching the TQFN exposed pad (TAB) must be connected to the ground plane underneath. The use of multiple via improves the package heat dissipation. Figure 27. TQFN-16 Recommended Layout http://onsemi.com 12 CAT3647 PACKAGE DIMENSIONS TQFN16, 3x3 CASE 510AD−01 ISSUE A D A e b L E E2 PIN#1 ID PIN#1 INDEX AREA TOP VIEW A1 SIDE VIEW D2 BOTTOM VIEW SYMBOL A A1 A3 b D D2 E E2 e L MIN 0.70 0.00 0.18 2.90 1.40 2.90 1.40 0.30 NOM 0.75 0.02 0.20 REF 0.25 3.00 −−− 3.00 −−− 0.50 BSC 0.40 MAX 0.80 0.05 0.30 3.10 1.80 3.10 1.80 0.50 A1 FRONT VIEW A3 A Notes: (1) All dimensions are in millimeters. (2) Complies with JEDEC MO-220. http://onsemi.com 13 CAT3647 Example of Ordering Information (Note 4) Prefix CAT Device # 3647 Suffix HV3 −G T2 Company ID (Optional) Product Number 3647 Package HV3: TQFN Lead Finish G: NiPdAu Tape & Reel (Note 6) T: Tape & Reel 2: 2,000 / Reel 2. 3. 4. 5. 6. All packages are RoHS−compliant (Lead−free, Halogen−free). The standard lead finish is NiPdAu. The device used in the above example is a CAT3647HV3−GT2 (TQFN, NiPdAu, Tape & Reel, 2,000/Reel). For additional package and 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. EZDim is a trademark of Semiconductor Components Industries, LLC. Quad−Mode is a registered trademark of Semiconductor Components Industries, LLC. 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. 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