19-0625; Rev 1; 1/07 KIT ATION EVALU E L B A AVAIL EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback The MAX16805/MAX16806 LED drivers eliminate the need for microcontrollers or switch-mode converters for automotive interior dome, map, and courtesy light applications. An EEPROM-programmable LED currentsense reference simplifies production by using one sense resistor to set the LED current for all LED bins. A dual-mode DIM pin and an on-board 200Hz ramp generator allow for PWM dimming with an analog or PWM control signal. The analog control signal at dimming input DIM allows for the “theater dimming” effect to be implemented. Fast turn-on/-off times ensure a widerange PWM operation, while waveshaping circuitry minimizes EMI. EEPROM-programmable LED current foldback makes it possible to operate at a high input voltage, while saving the cost and space associated with having a large heatsink. The MAX16806 works with an external thermal sensor to maintain maximum LED junction temperature by folding back the LED current. The thermal foldback temperature knee and slope are EEPROM programmable. The MAX16806 SW pin supplies necessary wetting current to a momentary switch. Features ♦ EEPROM or I2C Dynamically Programmable: ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ LED Current Foldback for High Input Voltage LED Current Reference LED Current Thermal Foldback (MAX16806) On-Board 200Hz Ramp Generator Eliminates the Need for µC PWM Signal Flexible Analog or PWM Control for PWM or Theater Dimming Wetting Current and Debounce for Momentary Switch (MAX16806) 5.5V to 40V Input with Up to 39V Output Capability 35mA to 350mA Adjustable LED Current Waveshaping Minimizes EMI During Dimming Output Short-Circuit and Overtemperature Protection -40°C to +125°C Operating Temperature Range Ordering Information PART Applications Automotive Interior: Map, Dome, and Courtesy Lighting TEMP RANGE PIN PACKAGE PKG CODE MAX16805ATP+ -40°C to +125°C 20 TQFN-EP** T2055M-5 MAX16806ATP+ -40°C to +125°C 20 TQFN-EP** T2055M-5 +Denotes lead-free package. Automotive Exterior: Rear Combination Light (RCL) Daytime Running Light (DRL) Adaptive Front Light **EP = Exposed pad. Pin Configurations appear at end of data sheet. Emergency Vehicle Warning Lights Navigation and Marine Indicators Typical Operating Circuits +5.5V TO +40V OUT 0.1μF SCL SERIAL DATA SDA MAX16805 LEDs OUT EN V5 +5V REG 0.1μF LEDs VCC MAX16806 CS+ V5 IN 0.1μF V5 0.1μF SERIAL CLOCK V5 +5V REG EN ILED +5.5V TO +40V ILED IN MAX6613† OUT CS+ TFP/SCL RSENSE RSENSE GND TFN/SDA CS- CSSW DIM PWM DIMMING DIM GND ANALOG CONTROL PWM DIMMING †MAX6613 THERMAL SENSOR IS OPTIONAL. GND PWM CONTROL DIMMING ________________________________________________________________ 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 MAX16805/MAX16806 General Description MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +45V DIM, OUT, EN to GND ................................-0.3V to (VIN + 0.3V) IN Slew Rate (20V < VIN < 45V) ...................................250mV/µs SDA, SCL (MAX16805), TFN/SDA, TFP/SCL (MAX16806) to GND...............................-0.3V to +6V CFD, CS+, V5 to GND ..............................................-0.3V to +6V DGND and CS- to GND.........................................-0.3V to +0.3V OUT Short Circuited to GND Duration (VIN < +16V)..........1 hour Maximum Current Into Any Pin (except IN and OUT) ......±20mA Continuous Power Dissipation (TA = +70°C) 20-Pin Thin QFN (derate 34.5mW/°C above +70°C)....2758.6mW Operating Temperature Range .........................-40°C to +125°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 = VEN = 12V, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, VDIM = 4V, DGND = GND, TFP/SCL = 5V, TFN/SDA = 0V, SW = CFD = Open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Supply Voltage Range Ground Current Shutdown Supply Current Guaranteed Output Current SYMBOL (Note 2) IG ILOAD = 350mA VEN ≤ 0.3V ISHDN IOUT MIN TYP MAX UNITS 40 V 2.5 4.5 mA 12 40 5.5 RSENSE = 0.55Ω 350 ΔVDO µA mA 35mA < IOUT < 350mA, RSENSE tolerance not included Output Current Accuracy Dropout Voltage (Note 3) CONDITIONS VIN 3.0 IOUT = 350mA, 12V < VIN < 40V 0.4 1.2 IOUT = 350mA, 6.5V < VIN < 12V 0.5 1.5 Output Current Slew Rate (External PWM Signal at DIM) Current rising, DIM rising to 4V 17 Current falling, DIM falling to 0.6V 17 Short-Circuit Current VOUT = 0V 600 % V mA/µs mA ENABLE INPUT EN Input Current IEN EN Input-Voltage High VIH EN Input-Voltage Low VIL Enable Turn-On Time tON 100 2.8 V 0.6 EN rising edge to 90% of OUT nA 225 V µs 5V REGULATOR Output Voltage Regulation (MAX16806) 0 < IV5 < 0.5mA, SW = GND V5 6.5V < VIN < 40V 4.9 5.1 5.3 V 0 < IV5 < 2mA, SW = open 4.9 5.1 5.3 0 < IV5 < 2mA, 6.5V < VIN < 40V 4.9 5.1 5.3 V VSENSE = [VCS+ - VCS-], Binning Adjustment register at factory default (0x0F) 192 198 204 mV Input Current (CS+) VCS+ = 210mV 12 Input Current (CS-) VCS+ = 210mV Output Voltage Regulation (MAX16805) V5 CURRENT SENSE Regulated RSENSE Voltage 2 VRSNS _______________________________________________________________________________________ µA -75 µA EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback (VIN = VEN = 12V, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, VDIM = 4V, DGND = GND, TFP/SCL = 5V, TFN/SDA = 0V, SW = CFD = Open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX Minimum Regulated VSENSE Programming Range VSENSE(MIN) 99.4 103 106.6 Maximum Regulated VSENSE Programming Range VSENSE(MAX) 192 198 204 Regulated VSENSE Default Voltage VSENSE(DEF) UNITS mV Binning Adjustment register at factory default (0x0F) 198 mV EXTERNAL PWM DIMMING INPUT DIM Input Current 0.5 µA Turn-On Time tON After DIM rising to 4V (Note 4) 28 52 µs Turn-Off Time tOFF After DIM falling to 0.6V (Note 4) 19 38 µs 335 354 THERMAL FOLDBACK (MAX16806 with MAX6613) Maximum Thermal Foldback Knee Point Programming Range TFKNEE(MAX) 326 mV Minimum Thermal Foldback Knee Point Programming Range TFKNEE(MIN) Minimum Thermal Foldback Temperature Programming Range TF(MIN) +60 Maximum Thermal Foldback Temperature Programming Range TF(MAX) +135 1143 1174 1213 °C Thermal Foldback Default Threshold Temperature VTH Thermal Foldback Default Threshold Voltage TFVTH Thermal Foldback Knee Point register at factory default (0x00) +60 °C 1.174 V Minimum Thermal Foldback Slope TFSL(MIN) 3.88 4 4.12 V/V Maximum Thermal Foldback Slope TFSL(MAX) 15.52 16 16.48 V/V Thermal Foldback Slope Gain register at factory default (0x03) Thermal Foldback Default Slope TFP/SCL (SCL for MAX16805) Voltage Compliance Range VTFP TFN/SDA (SDA for MAX16805) Voltage Compliance Range VTFN Minimum Thermal Foldback Clamp Current Reduction Range TFC(MIN) 4 V/V I2C interface active -0.3 V5 Remote thermal sensor active +0.3 V5 -0.3 V5 +25oC ≤ TA ≤ +125oC 40 V V % _______________________________________________________________________________________ 3 MAX16805/MAX16806 ELECTRICAL CHARACTERISTICS (continued) MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback ELECTRICAL CHARACTERISTICS (continued) (VIN = VEN = 12V, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, VDIM = 4V, DGND = GND, TFP/SCL = 5V, TFN/SDA = 0V, SW = CFD = Open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL Maximum Thermal Foldback Clamp Current Reduction Range TFC(MAX) Default Thermal Foldback Clamp Current Reduction Range TFDEF CONDITIONS MIN TYP MAX UNITS +25oC ≤ TA ≤ +125oC 100 % Thermal Foldback Clamp register at factory default (0x07), +25oC ≤ TA ≤ +125oC 40 % +155 °C +23 °C THERMAL PROTECTION Thermal Shutdown Temperature TJ(SHDN) Thermal Shutdown Hysteresis LED CURRENT FOLDBACK Minimum Input LED Current Foldback Range VCFD(MIN) 11.4 V Maximum Input LED Current Foldback Range VCFD(MAX) 16.4 V LED Current Foldback Threshold register at factory default (0x00) 16.4 V VIN > 11V, CFD register bit 3 = 0 0.71 VIN > 11V, CFD register bit 3 = 1 0.355 LED Current Foldback Default Level VCFD LED Current Foldback Voltage Step Size V/step INTERNAL RAMP GENERATOR Internal RAMP Frequency External Sync Frequency Range fRAMP 176 fDIM 80 200 External Sync Voltage Low External Sync Voltage High Hz Hz 0.4 V 2.8 VDIM = 0V Output Current Duty Cycle 224 2000 IDC V 0 VDIM > (VRAMP + 0.4V) (MAX16806), VDIM > +3.3V (MAX16805) % 100 Minimum Ramp Peak Programming Range VRAMP(MIN) 1.49 1.55 1.60 V Maximum Ramp Peak Programming Range VRAMP(MAX) 2.77 2.88 3.00 V Ramp Peak register at factory default (0x07) Ramp Peak Default Voltage Ramp Offset Voltage 2.88 V 210 mV MOMENTARY SWITCH INTERFACE (SW) (MAX16806) SW Pullup Current ISW VSW = 0V 1 SW Input-Voltage High VIH ISW = 100µA 4 SW Input-Voltage Low VIL 3 mA V 0.4 V Minimum Pulse Width 120 ms Minimum Debounce Time 40 ms 4 _______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback (VIN = VEN = 12V, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, VDIM = 4V, DGND = GND, TFP/SCL = 5V, TFN/SDA = 0V, SW = CFD = Open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS VIN Voltage for EEPROM Programming 20 22 24 V EEPROM Data-Retention Time 10 EEPROM Years I2C DIGITAL INPUTS (TFP/SCL, TFN/SDA) (Note 5) Logic Input-Voltage High VIH Logic Input-Voltage Low VIL 2.8 V 0.8 Input Capacitance 5 SDA Output Voltage Low VOL ISINK = 3mA V pF 0.4 V 400 kHz I2C INTERFACE TIMING (Figure 1) Serial Clock Frequency fSCL Bus Free Time Between STOP and START Condition tBUF 1.3 µs START Condition Hold Time tHD:STA 0.6 µs Clock Low Period tLOW 1.3 µs Clock High Period tHIGH 0.6 µs tSU:STA 0.6 µs Repeat START Condition Setup Time Data Hold Time tHD:DAT Data Setup Time tSU:DAT Receive SCL/SDA Rise Time tF STOP Condition Setup Time tSU:STO Transmit SDA Fall Time 0 0.9 µs 300 ns 100 ns tR Receive SCL/SDA Fall Time Pulse Width of Spike Suppressed A master device must provide a hold time of at least 300ns for the SDA signal (referred to VIL of the SCL signal) in order to bridge the undefined region of SCL’s falling edge 250 0.6 tSP 50 ISINK < 6mA, CB ≤ 400pF (Note 6) ns µs ns 250 ns Note 1: All devices 100% production tested at TJ = +25°C. Limits over the operating temperature range are guaranteed by design. Note 2: Resistors were added from OUT to CS+ to aid with the power dissipation during testing. Note 3: Dropout is measured as follows: Connect a resistor from OUT to CS+. Connect RSENSE = 0.56Ω from CS+ to CS-. Set VIN = VOUT +3V (record VOUT as VOUT1). Reduce VIN until VOUT = 0.97 x VOUT1 (record as VIN2 and VOUT2). ΔVDO = VIN2 - VOUT2. Note 4: tON time includes the delay and the rise time needed for IOUT to reach 90% of its final value. tOFF time is the time needed for IOUT to drop below 10%. See the Typical Operating Characteristics. tON and tOFF are tested with 13Ω from OUT to CS+. Note 5: TPF/SCL (SCL for MAX16805) and TPN/SDA (SDA for the MAX16805) are I2C interface compatible only when the MAX16805/MAX16806 are the only parts on the bus for production programming. Note 6: CB is the total bus capacitance. _______________________________________________________________________________________ 5 MAX16805/MAX16806 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VIN = 12V, VEN = VIN, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, SW = VFD = open, VTFP/SC = 5V, VTFN/SD = GND, DGND = GND. TA = +25°C, unless otherwise noted.) 300 250 ILOAD = 200mA 200 150 0.203 0.202 0.201 0.200 0.199 0.198 ILOAD = 100mA 100 350 IOUT = 350mA 300 250 200 150 IOUT = 100mA 100 0.197 ILOAD = 35mA 50 50 0.196 0 0.195 0 0 2 4 6 8 10 12 20 50 80 110 140 170 200 230 260 290 320 350 TEMPERATURE (°C) OUTPUT CURRENT (mA) INPUT VOLTAGE (V) DROPOUT VOLTAGE vs. TEMPERATURE +5V REGULATOR OUTPUT vs. TEMPERATURE +5V REGULATOR OUTPUT vs. INPUT VOLTAGE 0.7 0.6 0.5 0.4 0.3 0.2 5.10 ILOAD = 2mA 5.05 16 MAX16805 toc06 MAX16805 toc05 NO LOAD ILOAD = 1mA 5.15 14 5.20 +5V REGULATOR OUTPUT (V) 0.8 5.20 +5V REGULATOR OUTPUT (V) VIN = 12V ILOAD = 350mA 0.9 MAX16805 toc04 -40 -25 -10 5 20 35 50 65 80 95 110 125 1.0 DROPOUT VOLTAGE (V) MAX16805 toc02 350 VIN = 12V 0.204 400 OUTPUT CURRENT (mA) ILOAD = 350mA (VCS+ - VCS-) (V) OUTPUT CURRENT (mA) 400 OUTPUT CURRENT vs. INPUT VOLTAGE (VCS+ - VCS-) vs. OUTPUT CURRENT 0.205 MAX16805 toc01 450 MAX16805 toc03 OUTPUT CURRENT vs. TEMPERATURE NO LOAD 5.15 5.10 ILOAD = 1mA ILOAD = 2mA 5.05 0.1 0 5.00 5.00 20 25 35 INPUT VOLTAGE (V) (VCS+ - VCS-) vs. IV5 200Hz DIMMED OPERATION VIN = 20V 20 VIN = 12V MAX16805 toc08 VIN = 12 0.2005 (VCS+ - VCS-) (V) VIN = 40V 40 MAX16805 toc09 0.2010 VDIM 2V/div 0.2000 0V ILOAD = 350mA VIN = 12V DIM PULSED AT 200Hz (1% DUTY CYCLE) 0.1995 0.1990 VIN = 6.5V ILOAD 200mA/div 0A 0.1985 5 0.1980 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 6 30 TEMPERATURE (°C) 25 10 15 TEMPERATURE (°C) 30 15 10 -40 -25 -10 5 20 35 50 65 80 95 110 125 MAX16805 toc07 35 5 -40 -25 -10 5 20 35 50 65 80 95 110 125 SHUTDOWN CURRENT vs. TEMPERATURE SHUTDOWN CURRENT (μA) MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback 0 1 2 3 4 5 6 7 8 20μs/div IV5 (mA) _______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback MAX16805 toc11 120 VDIM 2V/div VDIM 2V/div 0V 0V ILED 200mA/div ILED 200mA/div 0A 0A MAX16805 toc12 DIM PULSED AT 200Hz OUTPUT CURRENT DUTY CYCLE (%) MAX16805 toc10 DIM PULSED AT 200Hz OUTPUT CURRENT DUTY CYCLE vs. ANALOG DIM VOLTAGE LED CURRENT RISE TIME (EXPANDED) LED CURRENT FALL TIME (EXPANDED) VIN = 12V RAMP REGISTER = 0x07 CFD = GND TFP = 5V TFN = GND 100 80 60 40 20 0 0 20μs/div 20μs/div 1 2 3 4 VDIM (V) LED CURRENT THRESHOLD REGISTER = (0x07) 100 80 BIT3 = 1 60 40 BIT3 = 0 20 LED CURRENT THRESHOLD REGISTER = (0x00) 100 80 BIT3 = 1 60 40 BIT3 = 0 20 0 0 0 2 4 6 10 12 14 16 18 20 8 0 5 10 15 20 25 INPUT VOLTAGE (V) INPUT VOLTAGE (V) OUTPUT CLAMP vs. THERMAL FOLDBACK SLOPE OUTPUT RESPONSE TO SW INPUT 30 MAX16805 toc16 MAX16805 toc15 45 THERMAL SLOPE = 4V/V 40 35 OUTPUT CLAMP (%) 120 OUTPUT CURRENT DUTY CYCLE (%) MAX16805 toc13 OUTPUT CURRENT DUTY CYCLE (%) 120 MAX16805 toc14 OUTPUT CURRENT DUTY CYCLE vs. INPUT VOLTAGE OUTPUT CURRENT DUTY CYCLE vs. INPUT VOLTAGE VSW 5V/div THERMAL SLOPE = 4V/V 30 DEBOUNCE TIME DEBOUNCE TIME THERMAL SLOPE = 8V/V 25 THERMAL SLOPE = 12V/V 20 VSENSE 200mV/div 15 THERMAL KNEE = +60°C 10 5 THERMAL FOLDBACK CLAMP LEVEL = 40% 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 40ms/div VTFN (V) _______________________________________________________________________________________ 7 MAX16805/MAX16806 Typical Operating Characteristics (continued) (VIN = 12V, VEN = VIN, CV5 = 0.1µF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, SW = VFD = open, VTFP/SC = 5V, VTFN/SD = GND, DGND = GND. TA = +25°C, unless otherwise noted.) EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback MAX16805/MAX16806 Pin Description PIN 8 MAX16805 MAX16806 1, 20 1, 20 NAME OUT FUNCTION Current Regulated Output. Connect pins 1 and 20. Input Supply. Bypass IN with a 0.1µF (min) capacitor to GND. Connect pins 2 and 3. 2, 3 2, 3 IN 4 4 CFD 5 5 DGND 6 — SCL I2C Serial Clock Input 7 — SDA I2C Serial-Data Input/Output 8, 10, 16 8, 10,16 GND Ground 9, 11, 18 9, 18 N.C. LED Current Foldback Dimming Enable Input. Leave CFD unconnected to enable the current foldback dimming function. Drive CFD low to disable the LED current foldback dimming function. Digital Ground. Connect to GND. No Connection. Leave unconnected (internal connection). 5V Regulated Output. Connect a 0.1µF capacitor from V5 to GND. Connect pin 12 to 15. 12, 15 12, 15 V5 13 13 CS+ Positive Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS+ and CS- to program the output current level. 14 14 CS- Negative Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS- and CS+ to program the output current level. 17 17 DIM Dimming Input. See the Dimming Input (DIM) section. 19 19 EN Enable Input. Drive EN high to enable the output and the 5V regulator. — 11 SW Momentary Switch Interface. See the Momentary Switch Interface (SW) section. — 6 TFP/SCL Thermal Foldback Positive Input/I2C Serial Clock Input. See the Thermal Sensor Inputs/I2C Interface (TFP/SCL and TFN/SDA) section. — 7 TFN/SDA Thermal Foldback Negative Input/I2C Serial-Data Input/Output. See the Thermal Sensor Inputs/I2C Interface (TFP/SCL and TFN/SDA) section. EP EP EP Exposed Pad. Connect to the ground plane for improved power dissipation. Do not use as a ground connection for the part. _______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback V5 IN IN REGULATOR 1.25V TRIMMED BANDGAP EN I_REG OUT MAX16805 MAX16806 DIM GND DIFFERENTIAL SENSE AMPLIFIER THERMAL SHUTDOWN CS+ CS- IN CURRENT FOLDBACK CFD EEPROM 210mV 200Hz RAMP GENERATOR MUX AND LOGIC SW (N.C.) POR REFERENCE GENERATOR V5 V5 EEPROM AND SERIAL INTERFACE PULSE DETECTOR TRIMMED BANDGAP THERMAL FOLDBACK* TFP/SCL TFN/SDA (SDA) (SCL) *NOT PART OF THE MAX16805 ( ) MAX16805 _______________________________________________________________________________________ 9 MAX16805/MAX16806 Functional Diagram MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback SDA tBUF tHD:STA tLOW tR tSP tF SCL tHD:STA tSU:STA tHIGH P tSU:DAT STOP tSU:STO START tHD:DAT REPEATED START Figure 1. I2C Serial Interface Timing Diagram Detailed Description The MAX16805/MAX16806 are constant-current regulators that provide up to 350mA of current to one or more strings of high-brightness LEDs. A wide operating input voltage range of 5.5V to 40V makes the devices ideal for automotive applications. The MAX16805/MAX16806 feature the I2C interface that allows communication with the internal dynamic registers and EEPROM. Dynamic registers control the MAX16805/MAX16806 functions and can be updated in real time through the I2C interface. See Table 2 for register addresses. Turning off the input voltage clears the dynamic register contents. To save settings, store them into the EEPROM. The MAX16805/MAX16806 load the stored settings into the dynamic registers at power-up. In addition, during normal operation a write command to the EEPROM Content Transfer register loads the stored settings into the dynamic register. Information stored can be transferred into dynamic registers after issuing a “write” command to the EEPROM Content Transfer register. The MAX16805/MAX16806’s 5V regulator (V5) provides up to 2mA of current to external circuitry. However, the MAX16806’s 5V regulator can deliver 2mA of output current only when the momentary switch is not used. When the momentary switch is active, the MAX16806 achieves up to 0.5mA of current. In addition, the MAX16805/MAX16806 feature thermal and output shortcircuit protection. The wide operating voltage range helps protect the device against large transients up to 45V such as those found in load dump situations. 10 The MAX16805/MAX16806 use a feedback loop to control the output current. The differential voltage across the sense resistor is compared to a fixed reference voltage and the error is amplified to serve as the drive to the internal pass device, see the Functional Diagram. The MAX16805/MAX16806 offer a programmable LED current reference using the Binning Adjustment register. These devices are current controllers internally optimized for driving the impedance range expected from 1 to 10 (or more) high-brightness LEDs. Dimming Input (DIM) The MAX16805/MAX16806’s dimming input operates with either an analog or PWM control signal. If the pulse detector detects three edges of a PWM signal with a frequency range between 80Hz to 2kHz, the MAX16805/MAX16806 synchronize to external PWM input signal and pulse-width-modulate the LED current. If an analog control signal is applied to DIM, the MAX16805/MAX16806 compare the DC input to an internally generated 200Hz ramp to pulse-width-modulate the LED current. The maximum peak value of the 200Hz ramp can be programmed using the Ramp Peak register. This allows the LED current to be adjusted through the I2C interface from 50% (typ) to 100% in real time when VDIM is 1.54V. The output current duty cycle is adjustable from 0% to 100% (0.21V < VDIM < 3.1V). Use the following formula to calculate the output current duty cycle: Duty cycle = (VDIM - 0.21V) / VRAMP ______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback Thermal Sensor Inputs/I2C Interface (TFP/SCL and TFN/SDA) The MAX16806 features dual-function inputs, TFP/SCL and TFN/SDA. In programming mode, TFP/SCL and TFN/SDA serve as the I2C serial communication interface. TFP/SCL and TFN/SDA also serve as inputs for analog signals generated by an external temperature sensor such as the MAX6613. When the thermal sensor is not used, connect TFP/SCL and TFN/SDA through 50kΩ resistors to V5 and GND, respectively. The MAX16805 does not offer dual-function inputs. SCL and SDA are used only to communicate with the MAX16805 through the I2C interface. Momentary Switch Interface (SW) The MAX16806 offers a momentary switch (SW) that overrides the analog dimming signal by latching the output current to 100% duty cycle. The MAX16806 does not override external PWM signal at DIM or dimming caused by thermal or LED current foldback. To latch the output current into a 100% duty cycle, press SW once. To restore the initial duty cycle determined by the DC level at DIM, press SW again. The MAX16806 provides a minimum of 1mA of wetting current to the momentary switch. Overtemperature Protection The MAX16805/MAX16806 enter a thermal shutdown in the event of overheating. This typically occurs in overload or output short-circuit conditions. When the junction temperature exceeds T J = +155°C (typ), the internal thermal protection circuitry turns off the pass device. The MAX16805/MAX16806 recover from thermal shutdown once the junction temperature drops by +23°C (typ). This feature allows self-protection by thermally cycling in the event of a short-circuit or overload condition. Digital Interface The MAX16805/MAX16806 feature an I2C, 2-wire serial interface consisting of a bidirectional serial data line (SDA) and a serial clock line (SCL). SDA and SCL facilitate bidirectional communication between the MAX16805/MAX16806 and the master device at rates VIN IN OUT EN V5 +5V REG THEATER DIMMING SIGNAL LEDs 0.1μF MAX16805 MAX16806 CS+ RSENSE CS- DIM GND Figure 2. Theater Dimming Light SDA SCL S P START CONDITION STOP CONDITION Figure 3. I2C Communication Start and Stop Conditions up to 400kHz. The master (typically a microcontroller) initiates data transfer on the bus and generates SCL. Start and Stop Conditions Both SCL and SDA remain high when the interface is not busy. A master controller signals the beginning of a transmission with a START condition by transitioning SDA from high to low while SCL is high. The master controller issues a STOP condition by transitioning the SDA from low to high while SCL is high, when it finishes communicating with the slave. The bus is then free for another transmission (Figure 3). ______________________________________________________________________________________ 11 MAX16805/MAX16806 The dimming feature can be used for LED brightness adjustment (see the Typical Operating Circuits) and theater dimming. If the external PWM signal is used, theater dimming can be achieved by varying the PWM duty cycle. Figure 2 shows a simple circuit that implements theater dimming with a DC input signal. MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback Bit Transfer One data bit is transferred during each clock pulse. The data on the SDA line must remain stable while SCL is high (Figure 4). Acknowledge The acknowledge bit is a clocked 9th bit that the recipient uses to handshake receipt each byte of data (Figure 5). Therefore, each byte effectively transferred requires 9 bits. The master controller generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, so the SDA line remains stable low during the high period of the clock pulse. Slave Address The MAX16805/MAX16806 have a 7-bit-long slave address (Figure 6, Table 1). The 8th bit following the 7bit slave address is the R/W bit. Set the R/W bit low for a write command and high for a read command. Table 1. Slave Address WRITE ADDRESS (HEX) READ ADDRESS (HEX) 0xEE 0xEF SDA SCL DATA STABLE, CHANGE OF DATA DATA VALID ALLOWED Figure 4. Bit Transfer NOT ACKNOWLEDGE START SDA ACKNOWLEDGE SCL 1 2 9 8 Figure 5. Acknowledge SDA START SCL A7 A6 A5 A4 A3 A2 A1 RW ACK 2 3 4 5 6 7 8 9 MSB 1 Figure 6. Slave Address 12 ______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback Table 2. Registers Address REGISTER ADDRESS NO. OF BITS/ REGISTER Binning Adjustment 0x00 4 Ramp Peak 0x01 3 LED Current Foldback Threshold (LED_CFT) 0x02 4 Thermal Foldback Knee Point 0x03 4 Thermal Foldback Slope Gain 0x04 2 Thermal Foldback Clamp Level 0x05 3 EEPROM Content Transfer 0x06 — EEPROM Program Enable 0x08 — Password Register 0xFF — REGISTER NAME an 8th bit (R/W) set to "1" if the current address location happens to be the address location from which data needs to be read. ACKNOWLEDGE FROM MAX16805/MAX16806 0 SLAVE ADDRESS S COMMAND BYTE A A P ACKNOWLEDGE FROM MAX16805/MAX16806 RW Figure 7. Command Byte Received ACKNOWLEDGE FROM MAX16805/MAX16806 S 0 SLAVE ADDRESS ACKNOWLEDGE FROM MAX16805/MAX16806 A RW COMMAND BYTE ACKNOWLEDGE FROM MAX16805/MAX16806 A DATA BYTE A P 1 BYTE Figure 8. Command and a Single Data Byte Received ______________________________________________________________________________________ 13 MAX16805/MAX16806 Message Format Write to the MAX16805/MAX16806 by transmitting the device’s slave address with R/W, 8th bit set to zero followed by at least 1 byte of information (Figure 7). The first byte of information is the command byte. The bytes received after the command byte are the data bytes. The first data byte goes into the internal register as selected by the command byte (Figure 8). If there is more than one data byte, the MAX16805/MAX16806 auto-increment to the next register address locations to write the subsequent data bytes. The MAX16805/ MAX16806 auto-increment up to the register address 0x05, EEPROM Content Transfer register. A read operation is performed as follows: After the START condition (S), a 7-bit slave ID is sent followed by an 8th bit (R/W) set to zero. A register address is then sent to specify the address location from which the read has to take place. To complete a read operation, the master needs to generate a repeated START (Sr) followed by the 7-bit slave ID but with the 8th bit (R/W) set to "1" this time indicating a read operation. On the other hand, a read operation can be performed by sending in the 7-bit slave ID followed by MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback Binning Adjustment Register (0x00) The Binning Adjustment register is a 4-bit register that sets the differential regulation voltage reference between CS+ and CS-. Only the first 4 bits of the data byte update the Binning Adjustment register. The remaining 4 bits are ignored. See Table 3. The factorydefault register value is 198mV. LED Current Foldback Threshold (LED_CFT) Register (0x02) LED_CFT is a 4-bit register that sets the threshold for the onset of the LED current foldback operation. Only the first 3 bits of the data byte program the LED_CFT register. Bit 3, not shown in Table 5, sets the LED current foldback range. The Ramp Peak register is a 3-bit register that sets the maximum peak value of an internally 200Hz generated ramp. The ramp signal can be programmed for a peak value of 1.55V to 2.88V. Only the first 3 bits of the data byte update the Ramp Peak register. The remaining 5 bits are ignored (see Table 4). The factory-default register value is 2.88V. The MAX16805/MAX16806 start dimming the LED current when the input voltage exceeds the LED current foldback threshold. For bit 3 = 0, the dimming range is 1.2 times the programmed ramp peak voltage. For bit 3 = 1, the dimming range is 2.4 times the programmed ramp peak. To disable the LED current foldback feature of the MAX16805/MAX16806 connect CFT to GND. The factory-default register value is 16V. Table 3. Binning Adjustment Table 4. Ramp Peak Value Ramp Peak Register (0x01), MAX16806 REGULATION VOLTAGE (mV) BIT 3 BIT 2 BIT 1 BIT 0 HEX RAMP END POINT (V) BIT 2 BIT 1 BIT 0 HEX 103.0 0 0 0 0 (0x00) 1.55 0 0 0 (0x00) 0 0 1 (0x01) 109.0 0 0 0 1 (0x01) 1.74 115.4 0 0 1 0 (0x02) 1.93 0 1 0 (0x02) 121.8 0 0 1 1 (0x03) 2.12 0 1 1 (0x03) (0x04) 2.32 1 0 0 (0x04) (0x05) 2.51 1 0 1 (0x05) 1 1 0 (0x06) 1 1 1 (0x07) 128.2 134.6 14 0 0 1 1 0 0 0 1 141.0 0 1 1 0 (0x06) 2.70 147.4 0 1 1 1 (0x07) 2.88 153.7 1 0 0 0 (0x08) 160.1 1 0 0 1 (0x09) 166.5 1 0 1 0 (0x0A) 173.0 1 0 1 1 (0x0B) 179.3 1 1 0 0 (0x0C) 185.7 1 1 0 1 (0x0D) 192.1 1 1 1 0 (0x0E) 198.0 1 1 1 1 (0x0F) Table 5. LED Current Foldback Threshold CURRENT FOLDBACK THRESHOLD (V) BIT 2 BIT 1 BIT 0 HEX 16.4 0 0 0 (0x00) 15.7 0 0 1 (0x01) 15.0 0 1 0 (0x02) 14.3 0 1 1 (0x03) 13.5 1 0 0 (0x04) 12.8 1 0 1 (0x05) 12.1 1 1 0 (0x06) 11.4 1 1 1 (0x07) ______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback Thermal Foldback Slope Gain Register (0x04), MAX16806 The TFK register is a 4-bit register that sets the thermal knee. Only the first 4 bits of the data byte program the TFK register. The remaining 4 bits are ignored (see Table 6). The MAX16806 initiates dimming once the differential voltage between TFP/SCL and TFN/SDA drops below the programmed thermal foldback knee. The factory-default register value is 1.174V, which corresponds to the MAX6613 thermal sensor output to +60°C. Thermal Foldback Slope Gain register is a 2-bit register that sets the gain after the thermal foldback knee. Only the first 2 bits of the data byte program the Thermal Foldback Slope Gain register. The remaining 6 bits are ignored (see Table 7). The factory-default register value is 4V/V. Table 6. Thermal Foldback Knee THERMAL FOLDBACK KNEE POINT (°C) (MAX6613) THERMAL FOLDBACK KNEE POINT (mV) BIT 3 BIT 2 BIT 1 BIT 0 HEX 60 1174 0 0 0 0 (0x00) 65 1118 0 0 0 1 (0x01) 70 1062 0 0 1 0 (0x02) 75 1006 0 0 1 1 (0x03) 80 950 0 1 0 0 (0x04) 85 894 0 1 0 1 (0x05) 90 838 0 1 1 0 (0x06) 96 782 0 1 1 1 (0x07) 101 726 1 0 0 0 (0x08) 106 670 1 0 0 1 (0x09) 111 615 1 0 1 0 (0x0A) 116 559 1 0 1 1 (0x0B) 121 503 1 1 0 0 (0x0C) 126 447 1 1 0 1 (0x0D) 131 391 1 1 1 0 (0x0E) 136 335 1 1 1 1 (0x0F) Table 7. Thermal Foldback Slope Gain THERMAL FOLDBACK SLOPE GAIN (V/V) BIT 1 BIT 0 HEX 16 0 0 (0x00) 12 0 1 (0x01) 8 1 0 (0x02) 4 1 1 (0x03) ______________________________________________________________________________________ 15 MAX16805/MAX16806 Thermal Foldback Knee Point (TFK) Register (0x03), MAX16806 MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback Thermal Foldback Clamp Level Register (0x05), MAX16806 Thermal Foldback Clamp Level is a 3-bit register that sets the minimum percentage of the LED current. Only the first 3 bits of the data byte program the Thermal Foldback Clamp Level register. The remaining 5 bits are ignored. See Table 8. The factory-default register value is 40%. EEPROM Content Transfer Register (0x06) The MAX16805/MAX16806 use the EEPROM Content Transfer register to transfer data from the EEPROM to the dynamic registers. A write command issued to this register transfers data from the EEPROM to the dynamic registers. Data bytes written to the EEPROM Content Transfer register do not have any significance. At power-up, the EEPROM content is automatically loaded into the dynamic registers. EEPROM Program Enable Register (0x08) The EEPROM Program Enable register enables the EEPROM for programming. Write to the EEPROM Programming Enable register to initiate the EEPROM programming cycle. Data written to the register does not have any significance, however, it must be issued following a write command [(0xFF), (0xCA)] to the Password register. Table 8. Thermal Foldback Clamp Level THERMAL FOLDBACK CLAMP LEVEL (%) BIT 2 BIT 1 BIT 0 HEX 100 0 0 0 (0x00) 91 0 0 1 (0x01) 83 0 1 0 (0x02) 74 0 1 1 (0x03) 66 1 0 0 (0x04) 57 1 0 1 (0x05) 49 1 1 0 (0x06) 40 1 1 1 (0x07) 16 Applications Information Programming the LED Current The MAX16805/MAX16806 use a sense resistor across CS+ and CS- to set the LED current. The differential sense amplifier connected across R SENSE provides ground-loop immunity and low-frequency noise rejection. The LED current is given by the equation below: ILED = VSENSE / RSENSE V SENSE is programmable from 103mV to 198mV using I2C. Programming EEPROM Set VIN to 22V before initiating the EEPROM programming. The MAX16805/MAX16806 use dynamic registers to program the EEPROM. Once the desired dynamic registers have been updated with a setting, write the data byte (0xCA) to the Password register (0xFF). The data byte (0xCA) enables the EEPROM programming mode. Any other data byte except the (0xCA) disables the EEPROM programming mode. To transfer data from dynamic registers to the EEPROM, write to EEPROM Program Enable register (0x08). Input Voltage Considerations For proper operation, the minimum input voltage must always be: VIN(MIN) > VSENSE + VFT(MAX) + ΔVDO(MAX) where VFT(MAX) is the total forward voltage of all series connected LEDs and ΔVDO(MAX) is the maximum drop output voltage. ______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback V5 CS- CS+ V5 N.C. V5 CS- CS+ V5 SW TOP VIEW 15 14 13 12 11 15 14 13 12 11 GND 16 10 GND GND 16 10 GND DIM 17 9 N.C. DIM 17 9 N.C. 8 GND N.C. 18 8 GND 7 SDA EN 19 7 TFN/SDA 6 SCL OUT 20 6 TFP/SCL 2 3 4 5 1 CFD DGND OUT THIN QFN 2 3 4 5 DGND 1 IN + IN + OUT OUT 20 CFD EN 19 MAX16806 IN MAX16805 IN N.C. 18 THIN QFN Chip Information PROCESS: BiCMOS-DMOS ______________________________________________________________________________________ 17 MAX16805/MAX16806 Pin Configurations 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.) QFN THIN.EPS MAX16805/MAX16806 EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback 18 ______________________________________________________________________________________ EEPROM-Programmable, High-Voltage, 350mA LED Drivers with LED Current Foldback 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 ____________________ 19 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX16805/MAX16806 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.)