19-0790; Rev 0; 4/07 KIT ATION EVALU E L B AVAILA Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN The MAX8647/MAX8648 drive up to six white LEDs or two sets of RGB LEDs with regulated constant current for display backlight and fun light applications. By utilizing an inverting charge pump and extremely lowdropout adaptive current regulators, these ICs achieve very high efficiency over the full 1-cell Li+ battery voltage range and even with large LED forward voltage mismatch. The 1MHz fixed-frequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. The MAX8647/MAX8648 include thermal shutdown, openand short-circuit protection. The MAX8647 features an I 2C serial port, while the MAX8648 features a three-wire serial-pulse logic interface. Both devices support independent on/off and dimming for main and subbacklights. The dimming ranges are pseudo-logarithmic from 24mA to 0.1mA and off in 32 steps. Both devices include a temperature derating function to safely allow bright 24mA full-scale output current setting while automatically reducing current to protect LEDs at high ambient temperatures above +60°C. The MAX8647/MAX8648 are available in a 16-pin, 3mm x 3mm thin QFN package (0.8mm max height). Applications White LED Backlighting, Single or Dual Display Features ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ Six Adaptive Current Regulators Independent Voltage Supply for Each LED Individual LED Brightness Control (MAX8647) 24mA to 0.1mA Dimming Range I2C Interface (MAX8647) Serial-Pulse Dimming Logic (MAX8648) ±2% Accuracy, ±0.4% Matching (typ) Low 70µA Quiescent Current Low 1µA Shutdown Current Inrush Current Limit TA Derating Function Protects LEDs 16-Pin, 3mm x 3mm Thin QFN Package Ordering Information TOP MARK PKG CODE MAX8647ETE+ I2C interface 16 Thin QFN-EP* AFD T1633-5 Serial-pulse 16 Thin QFN-EP* logic AFE T1633-5 PART MAX8648ETE+ DIMMING PIN PACKAGE Note: All devices are specified over the -40°C to +85°C extended temperature range. +Denotes a lead-free package. *EP = Exposed paddle. Wide-Gamut RGB LED Display Backlighting Typical Operating Circuit Camera Flash or RGB Indicators Cellular Phones and Smartphones 1μF PDAs, Digital Cameras, and Camcorders LED3 LED4 LED5 TOP VIEW LED2 Pin Configuration 12 11 10 9 C1P INPUT 2.7V TO 5.5V 1μF C1N C2P C2N IN EP 1μF GND LED1 13 8 LED6 SDA (ENC) 14 7 NEG 6 C1N 5 C2N MAX8647ETE MAX8648ETE SCL (ENB) 15 1 2 3 4 GND C1P C2P + IN VDD (ENA) 16 THIN QFN WHITE OR RGB LED MAX8648 LED1 LED2 SERIALPULSE INTERFACE 1μF NEG ENA LED3 ENB LED4 ENC LED5 LED6 D1 D2 D3 D4 D5 D6 ( ) DESIGNATE PINS ON THE MAX8648 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX8647/MAX8648 General Description MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN ABSOLUTE MAXIMUM RATINGS VDD, IN, SCL, SDA, ENA, ENB, ENC to GND........-0.3V to +6.0V VDD, IN, SCL, SDA, ENA, ENB, ENC to NEG ........-0.3V to +6.0V NEG to GND .............................................................-6V to +0.3V C2N to GND .............................................................-6V to +0.3V C1P, C2P to GND .......................................-0.3V to (VIN + 0.3V) C2P to C1N ..................................................-0.3V to (VIN + 0.3V) LED_, C1N, C2N to NEG .............................-0.3V to (VIN + 0.3V) Continuous Power Dissipation (TA = +70°C) 16-Pin Thin QFN 3mm x 3mm (derate 20.8mW/°C above +70°C).............................................................1667mW Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond 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 beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VVDD = VIN = 3.6V, VGND = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS IN Operating Voltage 2.7 5.5 V VDD Operating Voltage 1.7 5.5 V 2.55 V Undervoltage-Lockout (UVLO) Threshold VIN rising 2.35 Undervoltage-Lockout Hysteresis IN Shutdown Supply Current (All Outputs Off) VDD Shutdown Supply Current IN Operating Supply Current VDD Operating Supply Current 2.45 100 VSCL = VSDA = VDD (MAX8647), VEN_ = 0V (MAX8648) TA = +25°C 0.4 TA = +85°C 0.4 TA = +25°C 0.1 TA = +85°C 0.1 Charge pump inactive, two LEDs enabled at 0.1mA setting 70 Charge pump active, 1MHz switching, all LEDs enabled at 0.1mA setting 1.6 Charge pump inactive, two LEDs enabled at 0.1mA setting, TA = +25°C 0.1 Charge pump active, 1MHz switching, all LEDs enabled at 0.1mA setting, TA = +85°C 0.1 mV 2.5 1.0 100 µA µA µA mA 1.0 µA Thermal-Shutdown Threshold +160 °C Thermal-Shutdown Hysteresis 20 °C I2C INTERFACE (MAX8647) Logic-Input High Voltage (SDA, SCL) VDD = 1.7V to 5.5V, hysteresis = 0.2 x VDD (typ) Logic-Input Low Voltage (SDA, SCL) VDD = 1.7V to 5.5V, hysteresis = 0.2 x VDD (typ) Filtered Pulse Width (tSP) VIN = 2.7V to 5.5V, VDD = 1.7V to 5.5V (Note 2) Logic-Input Current (SDA, SCL) 2 VIL = 0V or VIH = 5.5V TA = +25°C TA = +85°C 0.7 x VDD -1 V 0.01 0.1 _______________________________________________________________________________________ 0.3 x VDD V 50 ns +1 µA Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN (VVDD = VIN = 3.6V, VGND = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SDA Output Low Voltage CONDITIONS MIN ISDA = 3mA, for acknowledge (Note 2) TYP MAX 0.03 0.40 V 400 kHz I2C Clock Frequency UNITS Bus Free Time Between START and STOP (tBUF) (Note 2) 1.3 Hold Time Repeated START Condition (tHD_STA) (Note 2) 0.6 0.1 µs SCL Low Period (tLOW) (Note 2) 1.3 0.2 µs SCL High Period (tHIGH) (Note 2) 0.6 0.2 µs Setup Time Repeated START Condition (tSU_STA) (Note 2) 0.6 0.1 µs SDA Hold Time (tHD_DAT) (Note 2) 0 -0.01 µs SDA Setup Time (tSU_DAT) (Note 2) 100 50 ns Setup Time for STOP Condition (tSU_STO) (Note 2) 0.6 0.1 µs µs SERIAL-PULSE LOGIC (EN_) (MAX8648) Logic-Input High Voltage VIN = 2.7V to 5.5V Logic-Input Low Voltage VIN = 2.7V to 5.5V 1.4 Logic-nput Current VIL = 0V or VIH = 5.5V tSHDN (Figure 3) Time from EN_ held low to ILED_ = 0mA V 0.4 TA = +25°C -1 TA = +85°C 0.01 +1 0.1 4 µA ms tLO (Figure 3) 1 tHI (Figure 3) 1 µs 120 µs Initial tHI (Figure 3) First EN_ high pulse 500 V µs CHARGE PUMP Switching Frequency Soft-Start Time 4.3 1 MHz 0.5 ms Charge-Pump Regulation Voltage (VIN - VNEG) Open-Loop NEG Output Resistance (VNEG - 0.5 x VIN) / INEG 2.5 5.0 NEG Discharge Resistance in Shutdown or When the Charge Pump is Inactive All LEDs off, EN_ = GND 10 V 5 Ω kΩ LED1–LED6 CURRENT REGULATOR Current Setting Range Through an I2C or serial-pulse interface Current Accuracy VLED_ = 0.5V for charge-pump inactive, VLED_ = -0.9V, VNEG_ = -1.4V 0.1 24mA setting, TA = +25°C -2 24mA setting, TA = -40°C to derating function start temperature (Note 2) -5 1.6mA setting, TA = +25°C -15 24.0 ±1 +2 +5 ±5 mA % +15 _______________________________________________________________________________________ 3 MAX8647/MAX8648 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VVDD = VIN = 3.6V, VGND = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP Derating-Function Start Temperature Derating-Function Slope From derating-function start temperature LED_ RDSON °C %/°C Utilizing the charge pump 4 LED_ Current Regulator Switchover Threshold (Inactive to Active) VLED_ falling Ω Not utilizing the charge pump 60 120 Utilizing the charge pump 90 200 150 175 125 LED_ Current Regulator Switchover Hysteresis UNITS -2.5 3 24mA setting (Note 3) MAX +60 Not utilizing the charge pump LED_ Dropout mV mV 100 LED_ Leakage in Shutdown All LEDs off TA = +25°C 0.01 TA = +85°C 0.1 mV 5 µA Note 1: Limits are 100% production tested at TA = +25°C. Specifications over the operating temperature range are guaranteed by design. Note 2: Guaranteed by design. Note 3: LED dropout voltage is defined as the LED_ to GND voltage at which current into LED_ drops 10% from the value at VLED_ = 0.5V. Typical Operating Characteristics (VIN = 3.6V, VEN_ = VIN, circuit of Figure 1, TA = +25°C, unless otherwise noted.) EFFICIENCY vs. SUPPLY VOLTAGE (DRIVING SIX MATCHED LEDs) 20.8mA/LED 60 50 16mA/LED 1.6mA/LED 40 6.4mA/LED 30 20 80 20.8mA/LED 70 1.6mA/LED 16mA/LED 60 6.4mA/LED 50 90 80 70 60 16mA/LED 50 1.6mA/LED 40 30 20 10 10 0 3.0 3.3 3.6 INPUT VOLTAGE (V) 3.9 4.2 LEDs HAVE MISMATCHED VF 0 40 2.7 4 MAX8647/48 toc03 90 EFFICIENCY (%) 70 100 MAX8647/48 toc02 80 100 EFFICIENCY PLED/PBATT (%) 90 EFFICIENCY vs. SUPPLY VOLTAGE (DRIVING SIX LEDs) EFFICIENCY vs. Li+ BATTERY VOLTAGE (DRIVING SIX MATCHED LEDs) MAX8647/48 toc01 100 EFFICIENCY (%) MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN 4.2 3.9 3.8 3.7 3.6 3.5 3.4 3.0 Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED) 2.7 3.0 3.3 3.6 INPUT VOLTAGE (V) _______________________________________________________________________________________ 3.9 4.2 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN 20.8mA/LED 50 6.4mA/LED 40 30 20 60 3.0 3.3 3.6 4.2 3.9 80 6.4mA/LED 70 20.8mA/LED 60 50 LEDs HAVE MISMATCHED VF 40 2.7 4.2 3.9 3.8 3.7 LEDs HAVE MISMATCHED VF 40 3.6 4.2 3.9 3.5 3.4 3.0 3.8 3.7 3.6 3.5 3.4 3.0 INPUT VOLTAGE (V) Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED) Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED) INPUT CURRENT vs. INPUT VOLTAGE (DRIVING SIX LEDs) INPUT CURRENT vs. Li+ BATTERY VOLTAGE (DRIVING SIX LEDs) INPUT CURRENT vs. INPUT VOLTAGE (RGB MODULE) 120 ILED = 16mA LEDs HAVE MISMATCHED VF 60 ILED = 6.4mA 40 20.8mA/LED 120 16mA/LED 100 80 60 6.4mA/LED 40 20 0 3.2 4.2 3.7 ILED = 16mA 60 50 40 ILED = 4.8mA 30 ILED = 1.6mA 10 0 0 2.7 70 20 1.6mA/LED 20 ILED = 1.6mA ILED = 20.8mA 80 4.2 3.9 3.8 3.7 3.6 3.2 2.7 3.5 3.4 3.0 3.7 4.2 Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED) INPUT VOLTAGE (V) INPUT CURRENT vs. Li+ BATTERY VOLTAGE (RGB MODULE) INPUT RIPPLE VOLTAGE vs. SUPPLY VOLTAGE (DRIVING SIX WHITE LEDs) LED CURRENT MATCHING vs. INPUT VOLTAGE (16mA/LED) 70 16mA/LED 60 50 40 30 6.4mA/LED 20 14 12 16mA/LED 10 8 6.4mA/LED LEDs HAVE MISMATCHED VF 6 4 4.2 3.9 3.8 3.7 3.6 3.5 3.4 3.0 Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED) 16.8 16.6 16.4 16.2 16.0 15.8 15.6 15.2 1.6mA/LED 0 0 17.0 15.4 2 1.6mA/LED 10 20.8mA/LED LED CURRENT (mA) 20.8mA/LED 80 16 INPUT RIPPLE VOLTAGE (mVRMS) RGB MODULE: LUMEX SML-LX3632SISUGSBC 90 MAX8647/48 toc10 INPUT VOLTAGE (V) MAX8647/48 toc12 80 140 RGB MODULE: LUMEX SML-LX3632SISUGSBC 90 INPUT CURRENT (mA) 140 100 160 INPUT CURRENT (mA) 160 LEDs HAVE MISMATCHED VF 180 100 MAX8647/48 toc08 ILED = 20.8mA 180 200 MAX8647/48 toc07 200 INPUT CURRENT (mA) 1.6mA/LED LEDs HAVE MISMATCHED VF 0 INPUT CURRENT (mA) 70 90 50 10 100 80 MAX8647/48 toc06 90 100 EFFICIENCY PLED/PBATT (%) 70 16mA/LED MAX8647/48 toc11 EFFICIENCY (%) 80 100 MAX8647/48 toc05 90 EFFICIENCY PLED/PBATT (%) MAX8647/48 toc04 100 60 EFFICIENCY vs. Li+ BATTERY VOLTAGE (DRIVING SIX LEDs) EFFICIENCY vs. Li+ BATTERY VOLTAGE (DRIVING SIX LEDs) MAX8647/48 toc09 EFFICIENCY vs. SUPPLY VOLTAGE (DRIVING SIX LEDs) 2.7 15.0 3.2 3.7 SUPPLY VOLTAGE (V) 4.2 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 INPUT VOLTAGE (V) _______________________________________________________________________________________ 5 MAX8647/MAX8648 Typical Operating Characteristics (continued) (VIN = 3.6V, VEN_ = VIN, circuit of Figure 1, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VIN = 3.6V, VEN_ = VIN, circuit of Figure 1, TA = +25°C, unless otherwise noted.) 1x MODE OPERATING WAVEFORMS (VIN = 4V) LED CURRENT vs. TEMPERATURE 1.5x MODE OPERATING WAVEFORMS (VIN = 3V) MAX8647/48 toc15 MAX8647/48 toc14 MAX8647/48 toc13 30 25 LED CURRENT (mA) MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN AC-COUPLED 100mV/div AC-COUPLED VIN 100mV/div VIN 20 100mA/div IIN 15 100mA/div IIN 0A 0A 10 20mA/div 20mA/div 5 ILED ALL LEDs ON ILED = 24mA 0A ILED ALL LEDs ON ILED = 24mA 0 -40 -15 10 35 60 85 400ns/div 400ns/div TEMPERATURE (°C) STARTUP AND SHUTDOWN (MAX8648) SINGLE-WIRE PULSE DIMMING (MAX8648) MAX8647/48 toc16 ENA = ENB = ENC MAX8647/48 toc17 2V/div VEN_ AC-COUPLED 20mV/div VIN IIN 200mA/div 5V/div OPERATING IN 1x MODE, ALL 6 LEDs OPERATING VEN_ TOTAL ILED5 0A 20mA/div ILED5 2V/div 0A 0A 1ms/div 10ms/div LINE-TRANSIENT RESPONSE (VIN = 4.3V TO 3.8V TO 4.3V) LINE-TRANSIENT RESPONSE WITH MODE CHANGE (VIN = 3.8V TO 3.4V TO 3.8V) MAX8647/48 toc18 MAX8647/48 toc19 4.3V VIN 3.8V VIN IIN 200mA/div IIN 3.8V 3.4V 200mA/div 0A 24mA 20mA/div ILED6 1ms/div 6 0mA ILED6 24mA 20mA/div 1ms/div _______________________________________________________________________________________ 0A Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN PIN NAME FUNCTION 1 IN Supply Voltage Input. The input voltage range is 2.7V to 5.5V. Bypass IN to GND with a 1µF ceramic capacitor as close as possible to the IC. IN is high impedance during shutdown. Connect IN to the anodes of all the LEDs. 2 2 GND Ground. Connect GND to system ground and the input bypass capacitor as close as possible to the IC. 3 3 C1P Transfer Capacitor 1 Positive Connection. Connect a 1µF ceramic capacitor from C1P to C1N. 4 4 C2P Transfer Capacitor 2 Positive Connection. Connect a 1µF ceramic capacitor from C2P to C2N. 5 5 C2N Transfer Capacitor 2 Negative Connection. Connect a 1µF ceramic capacitor from C2P to C2N. An internal 10kΩ resistor pulls C2N to GND during shutdown. 6 6 C1N Transfer Capacitor 1 Negative Connection. Connect a 1µF ceramic capacitor from C1P to C1N. 7 7 NEG Charge-Pump Negative Output. Connect a 1µF ceramic capacitor from NEG to GND. In shutdown, an internal 10kΩ resistor pulls NEG to GND. Connect the exposed paddle to NEG directly under the IC. LED Current Regulators. Current flowing into LED_ is based on the internal registers. Connect LED_ to the cathodes of the external LEDs. LED_ is high impedance during shutdown. For the MAX8647, program any unused LED_ to off and LED_ can be shorted to ground or left unconnected. For the MAX8648, short any unused LED_ to IN prior to power-up to disable the corresponding current regulator. MAX8647 MAX8648 1 8–13 8–13 LED6–LED1 14 — SDA I2C Data Input. Data is read on the rising edge of SCL. 15 — SCL I2C Clock Input. Data is read on the rising edge of SCL. 16 — VDD Logic-Input Supply Voltage. Connect to the supply voltage driving SDA and SCL. Bypass VDD to GND with a 0.1µF ceramic capacitor. — 14, 15, 16 ENC, ENB, ENA — — EP Enable and Serial-Pulse Dimming Control. ENA controls LED1, LED2, and LED3. ENB controls LED4 and LED5. ENC controls LED6. Drive EN_ logic-high to turn on the IC and enable the corresponding LED_ at 24mA each. Drive an individual EN_ logic-low for greater than 4ms to turn off the corresponding-current regulators or drive all three EN_ low to place the IC in shutdown. See the Serial-Pulse Dimming Control (MAX8648) section. Exposed Paddle. Connect to NEG. _______________________________________________________________________________________ 7 MAX8647/MAX8648 Pin Description MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN Detailed Description The MAX8647/MAX8648 have an inverting charge pump and six current regulators capable of 24mA each to drive six white LEDs or two sets of RGB LEDs. The current regulators are matched to within ±0.4% (typ) providing uniform white LED brightness for LCD backlight applications. To maximize efficiency, the current regulators operate with as little as 0.15V voltage drop. Individual white LED current regulators conduct current to GND or NEG to extend usable battery life. In the case of mismatched forward voltage of white LEDs, only the white LEDs requiring higher voltage are switched to pull current to NEG instead of GND, further raising efficiency and reducing battery current drain. used. Figure 2 shows a timing diagram for the I2C protocol. The MAX8647 is a slave-only device, relying upon a master to generate a clock signal. The master (typically a microprocessor) initiates data transfer on the bus and generates SCL to permit data transfer. A master device communicates with the MAX8647 by transmitting the proper 8-bit address (0x9A) followed by the 8-bit control byte. Each 8-bit control byte consists of a 3-bit command code and 5 bits of data (Table 1). Each transmit sequence is framed by a START (A) condition and a STOP (L) condition (Figure 2). Each word transmitted over the bus is 8 bits long and is always followed by an ACKNOWLEDGE CLOCK PULSE (K). The power-on default settings for D4 to D0 are all 0, which indicates that all LED_ are off. Current-Regulator Switchover Serial-Pulse Dimming Control (MAX8648) When V IN is higher than the forward voltage of the white LED plus the 0.15V headroom of the current regulator, the LED current returns through GND. If this condition is satisfied for all six white LEDs, the charge pump remains inactive. When the input voltage drops so that the current-regulator headroom cannot be maintained for any of the individual white LEDs, the inverting charge pump activates and generates a voltage on the NEG pin that is no greater than 5V below VIN. Each current regulator contains circuitry that detects when it is in dropout and switches that current-regulator return path from GND to NEG. Since this is done on an LEDby-LED basis, the LED current is switched for only the individual LED requiring higher voltage, thus minimizing power consumption. When the LEDs are enabled by driving EN_ high, the MAX8648 ramps LED current to 24mA. Dim the LEDs by pulsing EN_ low (1µs to 500µs pulse width). Each pulse reduces the LED current based on the LED dimming table, Table 3. After the current reaches 0.1mA, the next pulse restores the current to 24mA. Figure 3 shows a timing diagram for EN_. ENA controls LED1, LED2, and LED3. ENB controls LED4 and LED5. ENC controls LED6. Low LED Current Levels The MAX8647/MAX8648 internally generate a PWM signal to obtain higher resolution at lower currents. See Single-Wire Pulse Dimming in the Typical Operating Characteristics section. As the ILED setting is below 6.4mA, the IC adjusts not only ILED DC current, but the duty cycle is controlled by the PWM signal. The frequency of the PWM dimming signal is set at 1kHz with a minimum duty cycle of 1/16 to avoid the LED flicking effect to human eyes. Table 1 shows the current level and the corresponding duty cycle. I2C Interface (MAX8647) An I 2 C 2-wire serial interface is provided on the MAX8647 to control the LEDs. The serial interface consists of a serial-data line (SDA) and a serial-clock line (SCL). Standard I 2 C write-byte commands are 8 If dimming control is not required, EN_ work as simple 100% brightness or off controls. Drive EN_ high to enable the LEDs, or drive EN_ low to disable. The IC is shutdown when all three EN_ are low for 4ms or longer. Table 1. Internal PWM Duty Cycle vs. LED Set Current ILED (mA) DUTY CYCLE (n/16) ILED (mA) DUTY CYCLE (n/16) 6.4 16 1.2 12 5.6 14 1.0 10 4.8 12 0.8 8 4.0 10 0.7 7 3.2 16 0.6 6 2.8 14 0.5 5 2.4 12 0.4 4 2.0 10 0.3 3 1.6 16 0.2 2 1.4 14 0.1 1 _______________________________________________________________________________________ Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN VIN 2.7V TO 5.5V C2 1μF C1N C2P C1P IN C2N TP7 NEG INVERTING CHARGE PUMP C1 1μF MAX8647/MAX8648 C3 1μF EP GND C4 1μF SEL MIN 1MHz OSCILATOR CURRENT REGULATOR VIN LED1 VDD (ENA) SCL (ENB) SDA (ENC) I2C OR SERIAL PULSE INTERFACE AND CONTROL CURRENT SOURCE CONTROL BIAS CURRENT REGULATOR LED2 CURRENT REGULATOR LED3 CURRENT REGULATOR LED4 CURRENT REGULATOR LED5 CURRENT REGULATOR LED6 THERMAL SHUTDOWN MAX8647 MAX8648 ( ) ARE FOR THE MAX8648 Figure 1. Block Diagram and Application Circuit Shutdown Mode The MAX8647 is shutdown when all LEDs are turned off through the I2C port. In shutdown, the I2C port is still active and ready to receive a command. The MAX8648 is shutdown when all three EN_ are held low for 4ms or longer. In shutdown, NEG is pulled to GND with a 10kΩ internal resistor. _______________________________________________________________________________________ 9 MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN Table 2. I2C Control Data Byte—Device Address 0x9A SDA CONTROL BYTE COMMAND FUNCTION DATA C2 C1 C0 D4 D3 D2 D1 D0 Not used 0 0 0 — — — — — LED1 current 0 0 1 24.0mA to 0.1mA and off in 32 steps LED2 current 0 1 0 24.0mA to 0.1mA and off in 32 steps LED3 current 0 1 1 24.0mA to 0.1mA and off in 32 steps LED4 current 1 0 0 24.0mA to 0.1mA and off in 32 steps LED5 current 1 0 1 24.0mA to 0.1mA and off in 32 steps LED6 current 1 1 0 24.0mA to 0.1mA and off in 32 steps Not used 1 1 1 — — — — — Note: C2 is MSB and D0 is LSB. The power-on default settings for D4 to D0 are all 0, which indicates that all LED_ are off. Table 3. MAX8647 I2C Data vs. LED Currents mA D4 D3 D2 D1 D0 mA 1 24 0 1 1 1 1 2.8 0 22.4 0 1 1 1 0 2.4 0 1 20.8 0 1 1 0 1 2 1 0 0 19.2 0 1 1 0 0 1.6 0 1 1 17.6 0 1 0 1 1 1.4 1 0 1 0 16 0 1 0 1 0 1.2 1 1 0 0 1 14.4 0 1 0 0 1 1 1 1 0 0 0 12.8 0 1 0 0 0 0.8 1 0 1 1 1 11.2 0 0 1 1 1 0.7 1 0 1 1 0 9.6 0 0 1 1 0 0.6 1 0 1 0 1 8 0 0 1 0 1 0.5 1 0 1 0 0 6.4 0 0 1 0 0 0.4 1 0 0 1 1 5.6 0 0 0 1 1 0.3 1 0 0 1 0 4.8 0 0 0 1 0 0.2 0 0 0 1 0.1 0 0 0 0 OFF D4 D3 D2 D1 D0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 4 0 1 0 0 0 0 3.2 0 Temperature Derating Function The MAX8647/MAX8648 contain a derating function that automatically limits the LED current at high temperatures to help protect the LEDs from damage. The derating function enables the safe usage of higher LED current at room temperature, thus reducing the number of LEDs required to backlight the display. The derating circuit lowers the LED current at approximately 2.5%/°C once the IC is above +60°C. The typical derating function characteristic is shown in the Typical Operating Characteristics. 10 Power-Up LED Detection and Fault Protection The MAX8648 contains special circuitry to detect shortcircuit conditions at power-up and disable the corresponding current regulator to avoid wasting battery current. Connect any unused LED_ to IN to disable the corresponding current regulator. If an LED fails short circuit, the current regulator continues the current regulated operation until power to the IC is cycled and the short circuit is detected. An open-circuit LED failure drives the voltage on the corresponding LED_ output ______________________________________________________________________________________ Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN tLOW B C tHIGH D E F G H I J K L MAX8647/MAX8648 A M SCL SDA tSU_STA tHD_STA tSU_DAT tHD_DAT tSU_STO F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE (OP/SUS BIT) H = LSB OF DATA CLOCKED INTO SLAVE I = SLAVE PULLS SMBDATA LINE LOW A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW tBUF J = ACKNOWLEDGE CLOCKED INTO MASTER K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION Figure 2. Definition of Timing for I2C Bus Table 4. MAX8648 Pulse Dimming Step vs. LED Currents mA MAX8648 DIMMING STEPS mA MAX8648 DIMMING STEPS 24.0 Startup or EN_ high 2.8 16 22.4 1 2.4 17 20.8 2 2.0 18 19.2 3 1.6 19 17.6 4 1.4 20 16.0 5 1.2 21 14.4 6 1.0 22 12.8 7 0.8 23 11.2 8 0.7 24 9.6 9 0.6 25 8.0 10 0.5 26 6.4 11 0.4 27 5.6 12 0.3 28 4.8 13 0.2 29 4.0 14 0.1 30 3.2 15 24.0 31 below the switch over threshold enabling the inverting charge pump. For the MAX8647, program any unused LED_ to off using the I2C interface. Unused LED_ can be connected to IN or left unconnected. Thermal Shutdown The MAX8647/MAX8648 includes a thermal-limit circuit that shuts down the IC above about +160°C. The IC turns on after it cools by approximately 20°C. Applications Information Input Ripple For LED drivers, input ripple is more important than output ripple. The amount of input ripple depends on the source supply’s output impedance. Adding a lowpass filter to the input of the MAX8647/MAX8648 further reduces input ripple. Alternatively, increasing CIN to 2.2µF (or 4.7µF) cuts input ripple in half (or in fourth) with only a small increase in footprint. ______________________________________________________________________________________ 11 MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN 0 1 2 3 4 5 26 27 28 29 30 31 INITIAL tHI > 120μs EN_ 24mA 22.4 20.8 19.2 tHI > 1μs tLO 1μs TO 500μs 17.6 24mA 22.4 tSHDN 4ms 16.0 ILED_ 0.6 0mA 0.5 0.4 0.3 0.2 0.1mA 0mA Figure 3. EN_ Timing Diagram Capacitor Selection Ceramic capacitors are recommended due to their small size, low cost, and low ESR. Select ceramic capacitors that maintain their capacitance over temperature and DC bias. Capacitors with X5R or X7R temperature characteristics generally perform well. Recommended values are shown in the Typical Operating Circuit. Using a larger value input capacitor helps to reduce input ripple (see the Input Ripple section). Driving LEDs with Multiple Supplies It is not necessary for the LED anodes to connect to IN. Figure 7 shows an example using separate supplies to power the LED_ groups of the MAX8648. In this example, the voltage source (V1) provides power for RGB LEDs (LED1, LED2, and LED3). V2 provides power for backlight LEDs (LED4 and LED5), and V3 provides power for a red charge indicator (LED6). PCB Layout and Routing The MAX8647/MAX8648 have a high-frequency, switched-capacitor voltage inverter. For best circuit performance, use a solid copper plane and place C1–C4 as close as possible to the MAX8647/MAX8648. Figure 4 shows the MAX8648 evaluation kit example layout. 12 Figure 4. MAX8648 Evaluation Kit Layout for C1–C4 Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN C2P C2N C1P 1μF INPUT 2.7V TO 5.5V NEG GND I2C PORT ON/OFF AND BRIGHTNESS VLOGIC 1.7V TO 5.5V EP GND WHITE OR RGB LED MAX8647 SDA LED2 SCL LED3 SERIALPULSE INTERFACE D4 D5 ENB LED4 ENC LED5 D1 D2 D3 D4 D5 D6 Figure 6. MAX8648 Typical Application Circuit 1μF C1P 1μF C1N C2P C2N 1μF NEG IN EP 1μF GND WHITE OR RGB LED MAX8648 LED1 LED2 SERIALPULSE INTERFACE LED3 LED6 Figure 5. MAX8647 Typical Application Circuit INPUT 2.7V TO 5.5V ENA D6 LED6 LED1 LED2 D3 LED5 0.1μF MAX8648 D2 LED4 VDD WHITE OR RGB LED D1 LED1 1μF IN 1μF EP C2N NEG IN 1μF C2P C1N ENA LED3 ENB LED4 ENC LED5 LED6 V1 V2 V3 D1 D2 D3 D4 D5 BACKLIGHT INPUT 2.7V TO 5.5V C1N 1μF RGB C1P 1μF 1μF MAX8647/MAX8648 1μF D6 RED CHARGE INDICATOR Figure 7. Driving LEDs with Multiple Supplies ______________________________________________________________________________________ 13 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) (NE - 1) X e E MARKING 12x16L QFN THIN.EPS MAX8647/MAX8648 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN E/2 D2/2 (ND - 1) X e D/2 AAAA e CL D D2 k CL b 0.10 M C A B E2/2 L E2 0.10 C C L 0.08 C C L A A2 A1 L L e e PACKAGE OUTLINE 8, 12, 16L THIN QFN, 3x3x0.8mm 21-0136 14 ______________________________________________________________________________________ I 1 2 Ultra-Efficient Charge Pumps for Six White/RGB LEDs in 3mm x 3mm Thin QFN PKG 8L 3x3 12L 3x3 REF. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. A 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 b 0.25 0.30 0.35 0.20 0.25 0.30 0.20 0.25 0.30 D 2.90 3.00 3.10 2.90 3.00 3.10 2.90 3.00 3.10 E 2.90 3.00 3.10 2.90 3.00 3.10 2.90 3.00 3.10 e L N 0.55 0.75 0.45 0.55 ND 2 3 NE 2 3 0 A1 A2 k 0.02 0.05 0 0.20 REF 0.25 - 0.65 0.30 12 8 0.02 0.25 - 0.40 0.50 16 4 4 0.05 0 0.20 REF - EXPOSED PAD VARIATIONS 0.50 BSC. 0.50 BSC. 0.65 BSC. 0.35 16L 3x3 0.02 0.05 0.20 REF - 0.25 - PKG. CODES E2 D2 MIN. NOM. MAX. MIN. NOM. MAX. PIN ID JEDEC TQ833-1 0.25 0.70 1.25 0.25 0.70 1.25 0.35 x 45° T1233-1 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEEC WEED-1 T1233-3 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 WEED-1 T1233-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° T1633-2 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 T1633F-3 0.65 0.80 0.95 0.65 0.80 0.95 0.225 x 45° WEED-2 T1633FH-3 0.65 0.80 0.95 0.65 0.80 0.95 0.225 x 45° WEED-2 T1633-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 T1633-5 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 - NOTES: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. N IS THE TOTAL NUMBER OF TERMINALS. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. DRAWING CONFORMS TO JEDEC MO220 REVISION C. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. WARPAGE NOT TO EXCEED 0.10mm. PACKAGE OUTLINE 8, 12, 16L THIN QFN, 3x3x0.8mm 21-0136 I 2 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 © 2007 Maxim Integrated Products SPRINGER is a registered trademark of Maxim Integrated Products, Inc. MAX8647/MAX8648 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)