19-3744; Rev 0; 7/05 T EVALUATION KI AVAILABLE Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs The MAX1707 provides complete light management for main display backlight, subdisplay backlight (or RGB indicator), and white LED camera flash with regulated constant current up to 610mA total. By utilizing adaptive 1x/1.5x/2x charge-pump modes and very-lowdropout current regulators, it achieves high efficiency over the full 1-cell Li+ battery input voltage range. The 1MHz fixed-frequency switching allows for tiny external components while the regulation scheme is optimized to ensure low EMI and low input ripple. An integrated derating function protects the LEDs from overheating during high ambient temperatures. The MAX1707 features an internally trimmed reference to set the maximum LED current. An I2C† serial port is used for on/off control and setting the LED currents in 32 linear steps. When using the RGB indicator, the I2C port provides 32k colors and programmable rampup/down rates. The camera flash may be turned on/off by the I2C port or a separate digital logic input. Applications Features ♦ Guaranteed 610mA Continuous Drive Capability 4 LEDs at 30mA Each for Main Display 3 LEDs at 30mA Each for Sub or RGB 400mA Total for Flash ♦ 2-Wire I2C Serial Port 5-Bit (32-Step) Linear Dimming 32k Colors Ramp-Up/Down Rates ♦ 92% Peak/83% Avg Efficiency (PLED/PBATT) ♦ Adaptive 1x/1.5x/2x Mode Switchover ♦ 0.3% (typ) LED Current Accuracy and Matching ♦ Low Input Ripple and EMI ♦ Low 0.1µA Shutdown Current ♦ Output Overvoltage Protection ♦ Thermal Derating Function Protects LEDs ♦ 24-Pin 4mm x 4mm Thin QFN Package Ordering Information Cell Phones and Smartphones PDAs, Digital Cameras, Camcorders PART TEMP RANGE PINPACKAGE MAX1707ETG -40°C to +85°C 24 Thin QFN 4mm x 4mm Displays with Up to 11 LEDs †Purchase of I2C components from Maxim Integrated Products, Inc., or one of its sublicensed Associated Companies, conveys a license under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips. PKG CODE T2444-4 Pin Configuration appears at end of data sheet. Typical Operating Circuit 1µF INPUT 2.7V TO 5.5V 4.7µF C1P IN PIN 1µF C1N C2P MAX1707 VDD 0.1µF I2C PORT ON/OFF AND BRIGHTNESS STROBE ON/OFF OUTPUT UP TO 610mA 10µF GND VLOGIC C2N OUT SCK SDA STB MAIN SUB OR RGB FLASH M1 M2 M3 M4 S1 S2 S3 F1 F2 F3 F4 PGND ________________________________________________________________ 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 MAX1707 General Description MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs ABSOLUTE MAXIMUM RATINGS VDD, IN, PIN, SCK, SDA, STB, OUT to GND .........-0.3V to +6.0V M_, S_, F_ to GND ....................................-0.3V to (VOUT + 0.3V) C1N, C2N to GND .......................................-0.3V to (VIN + 0.3V) C1P, C2P to GND ..-0.3V to greater of (VOUT + 0.3V) or (VIN + 0.3V) PGND to GND .......................................................-0.3V to +0.3V OUT Short Circuit to GND ..........................................Continuous Continuous Power Dissipation (TA = +70°C) 24-Pin Thin QFN (derate 20.8mW/°C above +70°C)...1666mW Operating Temperature Range ...........................-40°C to +85°C 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 (VIN = VPIN = VDD = 3.6V, VGND = VPGND = 0V, temperature derating disabled, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNIT IN Operating Voltage 2.7 5.5 V VDD Operating Range 2.7 5.5 V VIN rising or falling 2.25 2.60 V VOUT rising 4.75 Undervoltage-Lockout Threshold Undervoltage-Lockout Hysteresis Output Overvoltage-Protection Threshold IN + PIN No-Load Supply Current 50 5.25 1.5x or 2x mode 4.0 6.5 10% setting, 1x mode, flash off 0.35 IN + PIN Shutdown Supply Current All LEDs off, STB = SDA = SCK = VDD, I2C ready TA = +25°C 0.7 TA = +85°C 0.8 VDD Quiescent Current All LEDs off, STB = SDA = SCK = VDD, I2C ready TA = +25°C 0.1 TA = +85°C 0.1 Startup into 1x mode Soft-Start Time mV 5.00 5 1 V mA µA µA 0.5 ms Startup into 1.5x mode 1.0 Startup into 2x mode 1.5 LED Current Derating Function Start Temperature Temperature derating enabled +40 °C LED Current Derating Function Slope TA = +40°C to +85°C, temperature derating enabled -1.7 %/°C LED Current SUB Output Accuracy (Note 2) LED Current FLASH and MAIN Output Accuracy Maximum M_, S_, F_ Sink Current LED Dropout Voltage Default current setting, TA = +25°C -2 Default current setting, TA = -40°C to +85°C -5 Default current setting (Note 2) -5 ±0.3 28.5 30.0 95 100 M_, S_ F_ 100% LED setting (Note 3) 1.5x and 2x Mode Regulation Voltage 1x to 1.5x and 1.5x to 2x Mode Transition Threshold 2 VM_, VS_, VF_ falling ±0.3 +2 +5 +5 % % mA M_, S_ 40 90 F_ 40 90 mV 150 mV 100 mV _______________________________________________________________________________________ Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs (VIN = VPIN = VDD = 3.6V, VGND = VPGND = 0V, temperature derating disabled, TA = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER CONDITIONS MIN Input Voltage Mode Transition Hysteresis TA = +25°C 0.01 TA = +85°C 0.1 All LEDs off, STB = VDD OUT Pulldown Resistance in Shutdown All LEDs off, STB = VDD Maximum OUT Current VIN ≥ 3.2V, VOUT = 3.9V 1 610 mA 0.5 2.5 1.5x mode (1.5 x VIN - VOUT) / IOUT 1.5 3.5 2x mode (2 x VIN - VOUT) / IOUT 2.0 4.1 1 SDA = 111xxx00 29 SDA = 111xxx01 218 SDA = 111xxx10 219 SDA = 111xxx11 220 VDD = 2.7V to 5.5V Logic-Input Low Voltage VDD = 2.7V to 5.5V Logic-Input Current VIL = 0V or VIH = 5.5V SDA Output Low Voltage ISDA = 3mA µA kΩ 1x mode (VIN - VOUT) / IOUT Logic-Input High Voltage UNIT mV 5 Switching Frequency S1, S2, S3 (RGB) Full-Scale Ramp Time MAX 150 M_, S_, F_ Leakage in Shutdown Open-Loop OUT Resistance TYP Ω MHz µs VDD / 2 V 0.4 TA = +25°C 0.01 TA = +85°C 0.1 0.03 I2C Clock Frequency 1 V µA 0.4 V 400 kHz Bus-Free Time Between START and STOP tBUF 1.3 Hold Time Repeated START Condition tHD_STA 0.6 0.1 µs SCK Low Period tLOW 1.3 0.2 µs SCK High Period tHIGH 0.6 0.2 µs Setup Time Repeated START Condition tSU_STA 0.6 0.1 µs SDA Hold Time tHD_DAT 0 -0.01 µs SDA Setup Time tSU_DAT 100 50 ns Setup Time for STOP Condition tSU_STO 0.6 0.1 µs +160 °C 20 °C Thermal Shutdown Thermal-Shutdown Hysteresis µs Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. Note 2: LED current specification includes both accuracy and matching tolerance. Note 3: Dropout voltage is defined as the M2 or F3 to GND voltage at which current into M2 or F3 drops 10% from the value at 0.2V. All other current regulators are tested functionally by the accuracy test and guaranteed for low dropout by design. _______________________________________________________________________________________ 3 MAX1707 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) INPUT CURRENT vs. SUPPLY VOLTAGE DRIVING LUMILEDS LXCL-PWF1 FLASH 800 700 70 60 50 40 1.9mA/LED 30mA/LED 15mA/LED 30 600 500 400 20 200 10 100 SUPPLY VOLTAGE FALLING 0 200mA 3.1 3.5 3.9 4.3 4.7 5.1 5.5 300 250 15mA/LED 200 150 100 100mA 1.9mA/LED 50 0 2.7 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 2.7 3.1 3.5 3.9 4.3 4.7 5.1 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) INPUT CURRENT vs. SUPPLY VOLTAGE DRIVING 4 MAIN LEDs INPUT CURRENT vs. SUPPLY VOLTAGE DRIVING RGB LEDs LED CURRENT MATCHING vs. SUPPLY VOLTAGE (MAIN AND RGB AT FULL CURRENT) 350 30mA/LED 200 15mA/LED 250 200 30mA/LED 150 50 0 3.1 3.5 3.9 4.3 4.7 5.1 5.5 29.1 3.1 3.5 3.9 4.3 4.7 RED VF = 1.7V 4 WHITE VF = 2.9V 3.1 3.5 1.88 1.86 GREEN VF = 1.9V 3.9 BLUE VF = 3.4V THERMAL DERATING OFF 20 4 MAIN OR 4 FLASH LEDs 15 THERMAL DERATING ON 10 5 1.82 1.80 0 2.7 3.1 3.5 3.9 4.3 4.7 SUPPLY VOLTAGE (V) 5.1 5.5 -40 4.3 MAX1707 toc06 4.7 SUPPLY VOLTAGE (V) 25 LED CURRENT (mA) LED CURRENT (mA) 2.7 5.5 LED CURRENT vs. TEMPERATURE 30 MAX1707 toc07 1.96 1.84 5.1 SUPPLY VOLTAGE (V) 1.94 BLUE VF = 4.2V GREEN VF = 2V 28.8 2.7 LED CURRENT MATCHING vs. SUPPLY VOLTAGE (MAIN AND RGB AT 1.9mA/LED) 1.90 29.7 1.9mA/LED SUPPLY VOLTAGE (V) 1.92 30.0 29.4 0 2.7 5.5 30.3 15mA/LED 100 1.9mA/LED RED VF = 1.9V 4 WHITE VF = 3.4V 30.6 300 100 50 30.9 MAX1707 toc08 150 31.2 LED CURRENT (mA) 300 250 SUPPLY VOLTAGE FALLING 400 INPUT CURRENT (mA) 350 450 MAX1707 toc05 SUPPLY VOLTAGE FALLING 400 MAX1707 toc04 450 4 30mA/LED 350 400mA 300 SUPPLY VOLTAGE FALLING 400 INPUT CURRENT (mA) INPUT CURRENT (mA) 80 450 MAX1707 toc02 90 EFFICIENCY (%) 900 MAX1707 toc01 100 INPUT CURRENT vs. SUPPLY VOLTAGE DRIVING 4 MAIN LEDs AND RGB LEDs MAX1707 toc03 EFFICIENCY vs. SUPPLY VOLTAGE DRIVING 4 MAIN LEDs INPUT CURRENT (mA) MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 5.1 5.5 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs OPERATING WAVEFORMS 1X MODE OPERATING WAVEFORMS 1.5X MODE MAX1707 toc09 MAX1707 toc10 VOUT 50mV/div (AC-COUPLED) VOUT 50mV/div (AC-COUPLED) VIN 50mV/div (AC-COUPLED) VIN 50mV/div (AC-COUPLED) IIN 100mA/div IIN 100mA/div 0 0 1µs/div 1µs/div MAIN BACKLIGHT STARTUP WAVEFORM OPERATING WAVEFORMS 2X MODE MAX1707 toc12 MAX1707 toc11 5V/div VSDA 50mV/div (AC-COUPLED) VOUT 1V/div VOUT 50mV/div (AC-COUPLED) 100mA/div VIN IIN 0 IIN 200mA/div 0 0 1ms/div 1µs/div MAIN STARTUP WITH RGB ALREADY ON FLASH STARTUP WAVEFORM MAX1707 toc13 MAX1707 toc14 5V/div 1V/div VSDA VOUT 5V/div VSDA 1V/div VOUT 0 IIN 200mA/div 0 1ms/div 0 IIN 200mA/div 0 1ms/div _______________________________________________________________________________________ 5 MAX1707 Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) STROBE STARTUP WAVEFORM WITH MAIN ALREADY ON MAIN BRIGHTNESS CHANGE (1.9mA/LED TO 30mA/LED) MAX1707 toc15 MAX1707 toc16 V STB 5V/div VOUT 1V/div VSDA 5V/div VOUT 1V/div 0 IIN 200mA/div 0 0 100mA/div 0 IOUT 1ms/div 1ms/div LINE-TRANSIENT RESPONSE (4V TO 3.3V TO 4V) LINE-TRANSIENT RESPONSE WITH MODE TRANSITION (3.3V TO 2.7V TO 3.3V) MAX1707 toc17 MAX1707 toc18 VIN 1V/div VIN VOUT 4V 1V/div VOUT 1V/div 4V 1V/div 200mA/div IOUT IOUT 200mA/div 0 0 100µs/div 100µs/div RGB RAMP WAVEFORMS (BLUE-TO-YELLOW TRANSITION) RGB RAMP WAVEFORMS (BLUE-TO-YELLOW TRANSITION) MAX1707 toc20 MAX1707 toc19 FULL-BRIGHTNESS 1048ms RAMP TIME IRED HALF-BRIGHTNESS DEFAULT RAMP TIME 20mA/div 10mA/div IRED 0 0 IGREEN 20mA/div IGREEN 10mA/div 0 0 10mA/div 20mA/div IBLUE IBLUE 0 0 200ms/div 6 40ms/div _______________________________________________________________________________________ Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs PIN NAME FUNCTION 1 PIN 2 IN 3 GND Ground. Connect GND to system ground and the ground side of the input bypass capacitor as close to the IC as possible. 4 VDD Logic-Input Supply Voltage. Connect VDD to the logic supply driving SDA, SCK, and STB. Connect a 0.1µF ceramic capacitor from VDD to GND. 5 M4 6 M3 7 M2 8 M1 9 F4 10 F3 11 F2 12 F1 13 S3 14 S2 15 S1 16 STB Strobe Logic Input. Drive STB low to turn on the flash LEDs (F1, F2, F3, F4) at the current specified in the internal strobe register. Drive STB high to turn off the flash LEDs. Connect to VDD if the flash LEDs are turned on/off only by the I2C interface. 17 SCK I2C Clock Input. Data is read on the rising edge of SCK. 18 SDA I2C Data Input. Data is read on the rising edge of SCK. 19 C1N Transfer Capacitor 1 Negative Connection. Connect a 1µF ceramic capacitor from C1N to C1P. C1N is shorted to IN during shutdown. 20 C1P Transfer Capacitor 1 Positive Connection. Connect a 1µF ceramic capacitor from C1N to C1P. During shutdown, if VOUT > VIN, C1P is shorted to OUT. If VOUT < VIN, C1P is shorted to IN. 21 PGND 22 OUT Output. Connect a 10µF ceramic capacitor from OUT to PGND. The anodes of all the LEDs connect to OUT. OUT is pulled to ground through an internal 5kΩ resistor in shutdown. 23 C2P Transfer Capacitor 2 Positive Connection. Connect a 1µF ceramic capacitor from C2N to C2P. During shutdown, if VOUT > VIN, C2P is shorted to OUT. If VOUT < VIN, C2P is shorted to IN. 24 C2N Transfer Capacitor 2 Negative Connection. Connect a 1µF ceramic capacitor from C2N to C2P. C2N is shorted to IN during shutdown. — EP Power-Supply Voltage Input. Connect PIN to IN. Connect a 4.7µF ceramic capacitor from PIN to PGND. The input voltage range is 2.7V to 5.5V. PIN is high impedance during shutdown. Analog Supply Voltage Input. Connect IN to PIN. The input voltage range is 2.7V to 5.5V. IN is high impedance during shutdown. LED Cathode Connections. Current flowing into these pins is based on the internal I2C dimming registers. The charge pump regulates the lowest LED cathode voltage to 0.15V. Grounding any of these pins forces output overvoltage protection mode causing OUT to pulse on and off at approximately 5V. To avoid constantly operating in overvoltage protection mode, any unused LED cathode connection (M_, S_, or F_) must be connected to OUT. This disables the corresponding current regulator. These pins are high impedance in shutdown. M1 through M4 are for main display backlights. S1 through S3 are for subdisplay backlights or one RGB LED indicator. F1 through F4 are for LED flash. Any combination of M_, S_, and F_ can be connected together to drive higher current LEDs. Power Ground. Charge-pump switching ground. Connect to GND and EP as close to the IC as possible. Exposed Paddle. Connect to GND and PGND directly under the IC. _______________________________________________________________________________________ 7 MAX1707 Pin Description MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs C1 1µF INPUT 2.7V TO 5.5V C1P C1N C2 1µF C2P C2N PIN OUT 1x/1.5x/2x REGULATING CHARGE PUMP IN OUT COUT 10µF CIN 4.7µF ERROR AMP 1 PGND OVP MAX1707 1.25V REFERENCE 0.15V GND 0.6V SELECT MIN I2C AND CONTROL SCK SDA STB BRIGHTNESS CONTROL VDD STB CONTROL S1 D1 S2 D2 S3 D3 M1 D4 M2 D5 M3 D6 M4 D7 F1 D8 F2 D9 F3 D10 F4 D11 2.7V TO 5.5V CVDD 0.1µF + + + – – – ERROR AMP 2 RSET + + + + – – – – + + + + – – – – Figure 1. Functional Diagram 8 _______________________________________________________________________________________ Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs The MAX1707 charge pump operates in three modes to maintain high efficiency over a wide supply voltage range. The IC automatically selects between these three modes as described in the 1x/1.5x/2x Mode Switchover section. Current-sinking LED cathode connections are provided to drive four main (M_) and three sub (S_) LEDs at a regulated current up to 30mA each. The sub LED connections can be used for either subdisplay backlighting or one RGB indicator. The IC also contains four flash LED connections (F_) that sink up to 100mA each. These LED connections can be connected together in any combination to provide increased current up to 610mA total. An I2C serial port is used for on/off control and setting the LED currents in 32 linear steps. When using the RGB indicator, the I2C port provides 32k colors and programmable ramp-up/down rates. The camera flash can be turned on/off by the I2C port or a separate digital logic input with either method programmed to its own brightness level. 1x/1.5x/2x Mode Switchover When the input voltage is higher than the required output voltage needed to drive the LEDs, the MAX1707 pulls OUT up to the input voltage (in 1x mode), while still regulating the LED current with the current regulators. As the input voltage drops, the lowest LED cathode voltage falls below the 100mV switchover threshold, and the MAX1707 starts switching in 1.5x mode. When the input voltage is rising, the transition from 1.5x to 1x is made when VIN is greater than VOUT. When the MAX1707 is running in 1.5x mode and the input voltage is decreased, the lowest LED cathode voltage crosses the 100mV switchover threshold again. At this point, the MAX1707 changes to the 2x chargepump mode. With the input voltage rising and the MAX1707 in 2x mode, the IC changes to 1.5x mode once VIN is greater than 2/3 of the output voltage. Soft-Start The MAX1707 includes soft-start circuitry to limit inrush current at turn-on and mode transitions. When starting up, the output capacitor is charged directly from the input with a ramped current source (with no chargepump action) until the output voltage is near the input voltage. After 512µs, if all the LED cathodes are not above 100mV, the MAX1707 switches to 1.5x mode with the LED output current ramped from 1/32 to the programmed current in 1/32 steps. After another 512µs, if all the LED cathodes are not above 100mV, the MAX1707 switches to 2x mode, once again ramping the LED current from 1/32 to the programmed current in 1/32 steps. Any time the output voltage is less than 1.25V, the soft-start routine is reset to the 1x state. Thus, the startup time is 512µs, 1024µs, or 1536µs, depending on what mode is required after the completion of startup. Output-Current Settings The output currents for the main, sub, and flash current regulators are set using the I2C serial interface (see the I2C Interface section). The current for the four main LEDs is always equal and set with a single command. The currents for the three sub LEDs are set independently, allowing them to drive an RGB LED. The current-level settings for both the main and sub LEDs range from 0.9mA to 30mA, defaulting to 15mA each (see Tables 1, 2, and 3). Table 1. Control Data Byte SDA CONTROL BYTE FUNCTION COMMAND DATA C2 C1 C0 D4 D3 D2 D1 D0 On/Off Control 0 0 0 Main Sub3 Sub2 Sub1 Flash Main Brightness 0 0 1 32 steps, 30mA/LED max Sub1 Brightness 0 1 0 32 steps, 30mA max Sub2 Brightness 0 1 1 32 steps, 30mA max Sub3 Brightness 1 0 0 32 steps, 30mA max Flash Brightness 1 0 1 32 steps, 100mA/LED max, I2C enable Strobe Brightness 1 1 0 32 steps, 100mA/LED max, STB enable Other Functions 1 1 1 X X Temp Derate RGB Ramp Rate Note: C2 is MSB and D0 is LSB. X = Don’t care. _______________________________________________________________________________________ 9 MAX1707 Detailed Description MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs Table 2. Data and LED Currents DATA LED CURRENT (mA) D4 D3 D2 D1 D0 MAIN SUB1 SUB2 SUB3 FLASH STROBE 0 0 0 0 0 0.9 0.9 0.9 0.9 3.3 3.3 0 0 0 0 1 1.9 1.9 1.9 1.9 6.5 6.5 0 0 0 1 0 2.8 2.8 2.8 2.8 9.7 9.7 0 0 0 1 1 3.8 3.8 3.8 3.8 12.9 12.9 0 0 1 0 0 4.7 4.7 4.7 4.7 16.2 16.2 0 0 1 0 1 5.6 5.6 5.6 5.6 19.4 19.4 0 0 1 1 0 6.6 6.6 6.6 6.6 22.6 22.6 0 0 1 1 1 7.5 7.5 7.5 7.5 25.8 25.8 0 1 0 0 0 8.4 8.4 8.4 8.4 28.9 28.9 0 1 0 0 1 9.4 9.4 9.4 9.4 32.1 32.1 0 1 0 1 0 10.3 10.3 10.3 10.3 35.4 35.4 0 1 0 1 1 11.3 11.3 11.3 11.3 38.6 38.6 0 1 1 0 0 12.2 12.2 12.2 12.2 41.6 41.6 0 1 1 0 1 13.1 13.1 13.1 13.1 44.7 44.7 0 1 1 1 0 14.1 14.1 14.1 14.1 47.9 47.9 0 1 1 1 1 15.0 15.0 15.0 15.0 51.0 51.0 1 0 0 0 0 15.9 15.9 15.9 15.9 54.1 54.1 1 0 0 0 1 16.9 16.9 16.9 16.9 57.2 57.2 1 0 0 1 0 17.8 17.8 17.8 17.8 60.3 60.3 1 0 0 1 1 18.8 18.8 18.8 18.8 63.4 63.4 1 0 1 0 0 19.7 19.7 19.7 19.7 66.3 66.3 1 0 1 0 1 20.6 20.6 20.6 20.6 69.6 69.6 1 0 1 1 0 21.6 21.6 21.6 21.6 72.7 72.7 1 0 1 1 1 22.5 22.5 22.5 22.5 75.8 75.8 1 1 0 0 0 23.4 23.4 23.4 23.4 78.8 78.8 1 1 0 0 1 24.4 24.4 24.4 24.4 81.9 81.9 1 1 0 1 0 25.3 25.3 25.3 25.3 84.9 84.9 1 1 0 1 1 26.3 26.3 26.3 26.3 87.9 87.9 1 1 1 0 0 27.2 27.2 27.2 27.2 91.0 91.0 1 1 1 0 1 28.1 28.1 28.1 28.1 94.0 94.0 1 1 1 1 0 29.1 29.1 29.1 29.1 97.0 97.0 1 1 1 1 1 30.0 30.0 30.0 30.0 100.0 100.0 Note: Defaults in bold. 10 ______________________________________________________________________________________ Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs CONTROL BYTE (HEXADECIMAL) LED CURRENT (mA) MAIN SUB1 SUB2 SUB3 FLASH STROBE MAIN SUB1 SUB2 SUB3 FLASH STROBE 20 40 60 80 A0 C0 0.9 0.9 0.9 0.9 3.3 3.3 21 41 61 81 A1 C1 1.9 1.9 1.9 1.9 6.5 6.5 22 42 62 82 A2 C2 2.8 2.8 2.8 2.8 9.7 9.7 23 43 63 83 A3 C3 3.8 3.8 3.8 3.8 12.9 12.9 24 44 64 84 A4 C4 4.7 4.7 4.7 4.7 16.2 16.2 25 45 65 85 A5 C5 5.6 5.6 5.6 5.6 19.4 19.4 26 46 66 86 A6 C6 6.6 6.6 6.6 6.6 22.6 22.6 27 47 67 87 A7 C7 7.5 7.5 7.5 7.5 25.8 25.8 28 48 68 88 A8 C8 8.4 8.4 8.4 8.4 28.9 28.9 29 49 69 89 A9 C9 9.4 9.4 9.4 9.4 32.1 32.1 2A 4A 6A 8A AA CA 10.3 10.3 10.3 10.3 35.4 35.4 2B 4B 6B 8B AB CB 11.3 11.3 11.3 11.3 38.6 38.6 2C 4C 6C 8C AC CC 12.2 12.2 12.2 12.2 41.6 41.6 2D 4D 6D 8D AD CD 13.1 13.1 13.1 13.1 44.7 44.7 2E 4E 6E 8E AE CE 14.1 14.1 14.1 14.1 47.9 47.9 2F 4F 6F 8F AF CF 15.0 15.0 15.0 15.0 51.0 51.0 30 50 70 90 B0 D0 15.9 15.9 15.9 15.9 54.1 54.1 31 51 71 91 B1 D1 16.9 16.9 16.9 16.9 57.2 57.2 32 52 72 92 B2 D2 17.8 17.8 17.8 17.8 60.3 60.3 33 53 73 93 B3 D3 18.8 18.8 18.8 18.8 63.4 63.4 34 54 74 94 B4 D4 19.7 19.7 19.7 19.7 66.3 66.3 35 55 75 95 B5 D5 20.6 20.6 20.6 20.6 69.6 69.6 36 56 76 96 B6 D6 21.6 21.6 21.6 21.6 72.7 72.7 37 57 77 97 B7 D7 22.5 22.5 22.5 22.5 75.8 75.8 38 58 78 98 B8 D8 23.4 23.4 23.4 23.4 78.8 78.8 39 59 79 99 B9 D9 24.4 24.4 24.4 24.4 81.9 81.9 3A 5A 7A 9A BA DA 25.3 25.3 25.3 25.3 84.9 84.9 3B 5B 7B 9B BB DB 26.3 26.3 26.3 26.3 87.9 87.9 3C 5C 7C 9C BC DC 27.2 27.2 27.2 27.2 91.0 91.0 3D 5D 7D 9D BD DD 28.1 28.1 28.1 28.1 94.0 94.0 3E 5E 7E 9E BE DE 29.1 29.1 29.1 29.1 97.0 97.0 3F 5F 7F 9F BF DF 30.0 30.0 30.0 30.0 100.0 100.0 Note: Defaults in bold. ______________________________________________________________________________________ 11 MAX1707 Table 3. Control Data Byte (Hexadecimal) MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs mon anode RGB LED. Thirty-two programmable brightness levels (5 bits) per LED provide a total of 32k colors. To smooth the transition between different color/brightness settings, a controlled ramp is used when the sub LED current level is changed, when the sub LEDs are enabled, and when the LEDs are disabled. The ramp rate is set to one of four settings with the I2C interface (see Table 4). Table 4. RGB Ramp Rate CONTROL BYTE (HEXADECIMAL) RGB RAMP RAMP TIME FROM OFF TO RATE (A/s) FULL BRIGHTNESS (ms) E0 58.6 0.512 E1 0.114 262 E2 0.0572 524 E3 0.0286 1048 Temperature-Derating Function *Default in bold. The MAX1707 contains a temperature-derating function that automatically limits the LED current at high temperatures in accordance with the recommended derating curve of popular white LEDs. 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. In camera-light applications, the derating circuit protects the LEDs and PC board from overheating. The derating circuit limits the LED current by reducing the LED current above +40°C by approximately 1.7%/°C. The typical derating function characteristic is shown in the Typical Operating Characteristics. The temperature derating function is enabled/disabled using the I2C interface and is off by default. The flash LEDs are controlled either using the I2C interface or by pulsing the STB input low. There are two registers in the MAX1707 to set the flash current level. The FLASH register sets the LED current when the I2C interface is used to pulse the flash LEDs, and the STROBE register sets the LED current when the STB input is pulsed. The current-level settings for the flash LEDs range from 3.3mA to 100mA, with a default of 25.8mA (see Tables 1, 2, and 3). The strobe register has priority over the flash register when both strobe and flash are on. The LED cathode connections (M_, S_, and F_) can be connected together in any combination to allow the use of higher current LEDs. For example, to drive a single flash LED at up to 400mA, connect F1, F2, F3, and F4 together to the cathode of the flash LED. To avoid constantly operating in overvoltage protection mode, any unused LED cathode connection (M_, S_, or F_) must be connected to OUT. This disables the corresponding current regulator. I2C Interface An I 2 C 2-wire serial interface is provided on the MAX1707 to control LED brightness, flash, temperature deration, and RGB ramp rate. The serial interface consists of a serial data line (SDA) and a serial clock line (SCK). Standard I2C write-byte commands are used. Figure 2 shows a timing diagram for the I2C protocol. The MAX1707 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 RGB Color and Ramp-Rate Settings The three sub LED currents are controlled independently by the I2C interface, allowing for use of a com- A tLOW B tHIGH C D E F G H I J K L M SCK SDA tSU:STA tHD:STA 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 tSU:DAT tSU:STO tBUF tHD:DAT 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 J = ACKNOWLEDGE CLOCKED INTO MASTER K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION Figure 2. I2C Timing Diagram 12 ______________________________________________________________________________________ Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs STB S1 S2 S3 TOP VIEW SCK Pin Configuration 18 17 16 15 14 13 C1N 19 12 F1 C1P 20 11 F2 10 F3 9 F4 C2P 23 8 M1 C2N 24 7 M2 PGND 21 2 3 4 5 6 M3 1 M4 OUT 22 VDD MAX1707ETG GND Thermal Shutdown Thermal shutdown limits total power dissipation in the MAX1707. When the junction temperature exceeds +160°C, the MAX1707 turns off, allowing the IC to cool. The MAX1707 turns on and begins soft-start after the junction temperature cools by 20°C. This results in a pulsed output during continuous thermal-overload conditions. PC Board Layout and Routing The MAX1707 is a high-frequency switched-capacitor regulator. For best circuit performance, use a solid ground plane and place the capacitors as close to the IC as possible. Connect the exposed pad to GND and PGND, and allow sufficient copper area for cooling the IC. Refer to the MAX1707 evaluation kit for an example PC board layout. IN Output Overvoltage Protection In case an LED fails or the cathode is shorted to GND, the output overvoltage protection limits the output to 5V. When the MAX1707 detects the output voltage rising above 5V, it shuts off the charge pump. The charge pump restarts once the output voltage has dropped to 4.9V. To avoid constantly operating in overvoltage protection, any unused LED cathode connection (M_, S_, or F_) must be connected to OUT; this disables the corresponding current regulator. 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 largervalue input capacitor helps to reduce input ripple (see the Input Ripple section). SDA STB Logic Input The STB input is used to control the flash LEDs without accessing the I2C interface. When STB is driven low, the flash LEDs are driven to the current set in the STROBE register. Driving STB low overrides the flash register settings. With STB high, the flash LEDs are controlled by the I2C interface flash register and on/off control. Input Ripple In 1x mode, the input ripple of the MAX1707 is negligible. When the charge pump is switching in 1.5x or 2x mode, the input ripple depends on the load current and the output impedance of the source supply. The worstcase ripple occurs when the charge pump is operating in 1.5x mode. The switching waveforms in the Typical Operating Characteristics show the typical input ripple. For noise-sensitive applications, input ripple can be reduced by increasing the input capacitance. PIN Shutdown Mode When all the LEDs are off, the MAX1707 turns off the charge pump and enters low-power shutdown mode. When in shutdown, OUT is pulled to GND by an internal 5kΩ resistor, discharging the output capacitor. IN and PIN are high impedance during shutdown, but the I2C interface (powered from VDD) remains active. To enter shutdown, send control byte 0x00 to the I2C interface, and drive STB high. To exit shutdown, enable any of the LEDs with the I2C interface or STB input. Applications Information THIN QFN 4mm x 4mm Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ 13 MAX1707 generates SCK to permit data transfer. A master device communicates to the MAX1707 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 (see Table 1). Each transmit sequence is framed by a START (A) condition and a STOP (L) condition (see Figure 2). Each word transmitted over the bus is 8 bits long and is always followed by an acknowledge clock pulse. 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.) 24L QFN THIN.EPS MAX1707 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm 21-0139 14 ______________________________________________________________________________________ E 1 2 Light-Management IC with Efficient 1x/1.5x/2x Charge Pump for Backlight/Flash/RGB LEDs PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm 21-0139 E 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 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX1707 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.)