CAT3648 4-Channel Ultra High Efficiency LED Driver with 32 Dimming Levels Description Applications • • • • LCD Display Backlight Cellular Phones Digital Still Cameras Handheld Devices NC NC GND LED1 1 LED2 C2− LED3 C2+ LED4 C1− RSET C1+ VIN High Efficiency 1.33x Charge Pump Charge Pump: 1x, 1.33x, 1.5x, 2x Drives up to 4 LEDs at 25 mA Each 1−wire EZDim 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 3 mm x 3 mm, 16−pad TQFN Package These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant PIN CONNECTIONS NC • • • • • • • • • • • • TQFN−16 HV3 SUFFIX CASE 510AD VOUT Features http://onsemi.com EN/DIM The CAT3648 is a high efficiency fractional charge pump that can drive up to four 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 2.5 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 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 1.33x, charge pump switching architecture is patented. (Top View) MARKING DIAGRAM JAAN AXXX YWW JAAN = CAT3648HV3−GT2 A = Assembly Location XXX = Last Three Digits of Assembly Lot Number Y = Production Year (Last Digit) WW = Production Week (Two Digits) ORDERING INFORMATION Device Package Shipping† CAT3648HV3−GT2 (Note 1) TQFN−16 (Pb−Free) 2000 / Tape & Reel 1. NiPdAu Plated Finish (RoHS−compliant). †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. © Semiconductor Components Industries, LLC, 2014 August, 2014 − Rev. 3 1 Publication Order Number: CAT3648/D CAT3648 1 mF C1+ VIN 2.4 V to 5.5 V C1− C2+ VIN CIN 1 mF C2− VOUT CAT3648 1 mF 1−Wire EZDimt Programming COUT 1 mF LED1 EN/DIM LED2 LED3 RSET 3.74 kΩ VOUT 20 mA LED4 GND Figure 1. Typical Application Circuit Table 1. ABSOLUTE MAXIMUM RATINGS Parameter VIN, LEDx, C1±, C2±, EN/DIM voltage VOUT voltage Rating Unit 6 V 7 V Storage Temperature Range −65 to +160 °C Junction Temperature Range −40 to +150 °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. Table 2. RECOMMENDED OPERATING CONDITIONS Rating Unit VIN Parameter 2.5 to 5.5 V Ambient Temperature Range −40 to +85 °C ILED per LED pin up to 30 mA LED Forward Voltage Range 1.3 to 4.3 V Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond the Recommended Operating Ranges limits may affect device reliability. NOTE: Typical application circuit with external components is shown above. http://onsemi.com 2 CAT3648 Table 3. ELECTRICAL OPERATING CHARACTERISTICS (over recommended operating conditions unless specified otherwise) VIN = 3.6 V, EN = High, TAMB = 25°C Name Symbol Conditions Min Typ IQ Quiescent Current 1x mode, excluding load 1.33x mode, excluding load 1.5x mode, excluding load 2x mode, excluding load IQSHDN Shutdown Current VEN = 0 V LED Current Setting RSET = 3.74 kW 20 RSET = 7.50 kW 10 ±2 ILED−ACC ILED−ACC LED Current Accuracy (ILEDAVG – INOMINAL) / INOMINAL RSET = 4.99 kW ILED−DEV LED Channel Matching (ILED − ILEDAVG) / ILEDAVG Max 1.0 1.7 2.2 2.4 mA 1 % % VRSET RSET Regulated Voltage ROUT 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 FOSC Charge Pump Frequency 1.33x and 2x mode 1.5x mode ISC_MAX Output short circuit Current Limit VOUT < 0.5 V 50 mA IIN_MAX Input Current Limit VOUT > 1 V, 1x mode 250 mA LEDTH 1x to 1.33x or 1.33x to 1.5x or 1.5x to 2x Transition Thresholds at any LED pin 130 mV 1x Mode Transition Hysteresis 400 mV Mode Transition Filter Delay 120 ms 100 kW V V VHYS TDF REN/DIM VHI VLO EN/DIM Pin − Internal Pull−down Resistor − Logic High Level − Logic Low Level TSD Thermal Shutdown THYS Thermal Hysteresis VUVLO Undervoltage lockout (UVLO) threshold 0.6 mA mA ±1.5 0.58 Units 0.62 0.8 5 5 10 0.8 1 1 1.3 W 1.3 1.6 1.3 0.4 150 1.8 MHz °C 20 1.6 V °C 2.0 V 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. http://onsemi.com 3 CAT3648 Table 4. RECOMMENDED EN/DIM TIMING (For 2.4 V ≤ VIN ≤ 5.5 V, over full ambient temperature range −40°C to +85°C.) Name Symbol Conditions Min TLO EN/DIM program low time 0.2 THI EN/DIM program high time 0.2 EN/DIM low time to shutdown 1.5 TPWRDWN TLED LED current settling time Typ Max Units 100 ms ms ms 40 ms THI EN/DIM TLO TPWRDWN TLED 100% LED Current 100% 97% 94% 32 Levels Shutdown 3% 0% 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] RSET [kW] 2 37.4 5 14.7 10 7.50 15 4.99 20 3.74 25 3.00 30 2.49 http://onsemi.com 4 Shutdown CAT3648 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) 100 100 VF = 3.3 V VF = 3.3 V 1.33x 90 1.5x 90 1x 80 EFFICIENCY (%) EFFICIENCY (%) 1x 2x 70 60 50 40 4.5 4.0 3.5 3.0 2.5 4.0 3.8 3.6 3.4 3.2 INPUT VOLTAGE (V) Figure 3. Efficiency vs. Input Voltage Figure 4. Efficiency vs. Li−Ion Voltage 3.0 4 QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) 4.2 INPUT VOLTAGE (V) 3 2 1 LEDs Off 5.5 5.0 4.5 4.0 3.5 3.0 2.5 3 2x 1.5x 1.33x 2 1x 1 0 −40 2.0 0 40 80 120 INPUT VOLTAGE (V) TEMPERATURE (°C) Figure 5. Quiescent Current vs. Input Voltage Figure 6. Quiescent Current vs. Temperature 10 10 VF = 3.3 V 8 LED CURRENT VARIATION (%) LED CURRENT VARIATION (%) 60 40 2.0 VF = 3.3 V 6 4 2 0 −2 −4 −6 −8 −10 70 50 4 0 1.33x 80 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 8 VF = 3.3 V 6 4 2 0 −2 −4 −6 −8 −10 −40 0 40 80 INPUT VOLTAGE (V) TEMPERATURE (°C) Figure 7. LED Current Change vs. Input Voltage Figure 8. LED Current Change vs. Temperature http://onsemi.com 5 120 CAT3648 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) 12 1.2 OUTPUT RESISTANCE (W) SWITCHING FREQUENCY (MHz) 1.3 1.5x Mode 1.1 1.0 0.9 1.33x, 2x Mode 0.8 0.7 −40 0 40 80 10 8 6 1.5x 1.33x 4 2 0 120 2x 1x 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 TEMPERATURE (°C) 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 CAT3648 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 80 mA (4 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 CAT3648 TYPICAL PERFORMANCE CHARACTERISTICS (VIN = 3.6 V, IOUT = 80 mA (4 LEDs at 20 mA), CIN = COUT = C1 = C2 = 1 mF, TAMB = 25°C unless otherwise specified.) 40 4.0 1x Mode 3.0 LED CURRENT (mA) OUTPUT VOLTAGE (V) 3.5 2.5 2.0 1.5 1.0 30 20 10 0.5 0 0 100 200 300 0 400 0 50 100 150 200 250 OUTPUT CURRENT (mA) LED PIN VOLTAGE (mV) Figure 21. Foldback Current Limit Figure 22. LED Current vs. LED Pin Voltage Figure 23. Dimming Waveform http://onsemi.com 8 300 CAT3648 Table 6. PIN DESCRIPTION Pin # Name Function 1 LED2 LED2 cathode terminal. 2 LED3 LED3 cathode terminal. 3 LED4 LED4 cathode terminal. 4 RSET Connect resistor RSET to set the LED current. 5 EN/DIM 6 VOUT 7 NC Not connected inside the package. 8 VIN Charge pump input, connect to battery or supply. 9 C1+ Bucket capacitor 1 Positive terminal 10 C1− Bucket capacitor 1 Negative terminal 11 C2+ Bucket capacitor 2 Positive terminal 12 C2− Bucket capacitor 2 Negative terminal 13 NC Not connected inside the package. 14 NC Not connected inside the package. 15 GND Ground Reference 16 LED1 LED1 cathode terminal. TAB GND Connect to GND on the PCB. Device enable (active high) and Dimming Control. Charge pump output connected to the LED anodes. 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 to LED4 provide the internal regulated current source 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 CAT3648 Block Diagram C1+ VIN C1− C2− C2+ VOUT 1x mode (LDO) 4/3x, 3/2x, 2x Charge Pump 1, 1.3 MHz Oscillator EN/DIM Mode Control LED1 LED2 LED3 100 kΩ Serial Interface Reference Voltage Registers Current Setting DAC LED4 LED Channel Current Regulators RSET GND Figure 24. CAT3648 Functional Block Diagram Basic Operation At power−up, the CAT3648 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 CAT3648 LED Current Selection Table 7. DIMMING LEVELS 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 Full Scale Current in % Dimming Pulses [n] 100 0 97 1 94 2 90 3 87 4 84 5 81 6 77 7 74 8 71 9 68 10 ǒ3131* nǓ 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. 65 11 61 12 58 13 55 14 52 15 48 16 45 17 42 18 39 19 35 20 32 21 29 22 26 23 23 24 19 25 16 26 13 27 10 28 6 29 3 30 0 31 100 32 THI EN/DIM TLO TPWRDWN TLED 100% LED Current Shutdown 100% 97% 94% 32 Levels 3% 0% Figure 25. EN/DIM Digital Dimming Timing Diagram http://onsemi.com 11 Shutdown CAT3648 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). 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. 1 mF C1+ VIN VIN CIN C1− C2+ 1 mF C2− VOUT COUT CAT3648 1 mF LED1 ENABLE DIMMING EN/DIM LED2 RSET LED3 LED4 GND External Components 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. 1 mF RSET Figure 26. Application with 3 LEDs Recommended Layout 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. 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. GND Pin1 C2 EN/DIM C1 RSE T VIN GND CIN COUT GND Figure 27. Recommended Layout http://onsemi.com 12 CAT3648 PACKAGE DIMENSIONS TQFN16, 3x3 CASE 510AD ISSUE A A D e b L E2 E PIN#1 ID PIN#1 INDEX AREA A1 TOP VIEW SYMBOL MIN SIDE VIEW NOM A 0.70 0.75 0.80 0.00 0.02 0.05 0.20 REF b 0.18 0.25 0.30 D 2.90 3.00 3.10 D2 1.40 −−− 1.80 E 2.90 3.00 3.10 E2 1.40 −−− 1.80 e L BOTTOM VIEW MAX A1 A3 D2 A A3 A1 FRONT VIEW 0.50 BSC 0.30 0.40 0.50 Notes: (1) All dimensions are in millimeters. (2) Complies with JEDEC MO-220. 2. All packages are RoHS−compliant (Lead−free, Halogen−free). 3. The standard lead finish is NiPdAu. 4. For additional package and temperature options, please contact your nearest ON Semiconductor Sales office. ON Semiconductor and the are registered trademarks of Semiconductor Components Industries, LLC (SCILLC) or its subsidiaries in the United States and/or other countries. SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent−Marking.pdf. SCILLC reserves the right to make changes without further notice to any products herein. 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