MAX8790ETP+T Maxim Integrated Products, MAX8790ETP+T Datasheet
MAX8790ETP+T
Specifications of MAX8790ETP+T
Related parts for MAX8790ETP+T
MAX8790ETP+T Summary of contents
Page 1
... Thin QFN MAX8790ETP+ -40°C to +85°C (4mm x 4mm) + Denotes a lead-free package. ________________________________________________________________ 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. o Drives Six Parallel Strings with Multiple Series- Connected LEDs per String o ± ...
Page 2
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications ABSOLUTE MAXIMUM RATINGS IN, SHDN, to GND .................................................-0.3V to +28V FB_ to GND ............................................................-0.3V to +28V V , BRT, ENA, OSC GND ...........................-0.3V to +6V CC ...
Page 3
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 12V SHDN IN PARAMETER INPUT LEAKAGE SHDN Leakage Current SHDN = 26V CS Leakage Current V ...
Page 4
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications ELECTRICAL CHARACTERISTICS (Circuit of Figure 12V SHDN IN PARAMETER Input Voltage Range SHDN IN Quiescent Current ...
Page 5
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 12V SHDN IN PARAMETER LED CURRENT ISET = V Full-Scale FB_ Output Current R ISET R ...
Page 6
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications (Circuit configuration 12V, V SHDN IN BOOST CONVERTER EFFICIENCY vs. INPUT VOLTAGE (BRT = 100 500kHz 92 750kHz 1MHz 88 ...
Page 7
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications (Circuit configuration 12V, V SHDN IN SWITCHING WAVEFORMS (BRT = 15%, ANALOG DIMMING) MAX8790 toc10 V LX 10V/div 500mA/div 0mA 1μs/div LED ...
Page 8
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications (Circuit configuration 12V, V SHDN IN LED-SHORT FAULT PROTECTION (BRT = 100%, 2 LEDs SHORT ON FB3) 10ms/div PIN NAME O sci l l ator ...
Page 9
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications PIN NAME LED String 6 Cathode Connection. FB6 is the open-drain output of an internal regulator, which controls 11 FB6 current through FB6. FB6 can sink up to ...
Page 10
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications Detailed Description The MAX8790 is a high-efficiency driver for arrays of white LEDs. It contains a fixed-frequency, current- mode, PWM step-up controller, 5V linear regulator, dim- ming control ...
Page 11
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications IN 5V LINEAR REGULATOR OSCILLATOR TRI-LEVEL OSC COMPARATOR SHDN CCV REF ADJ ISET CLK OSC FSET 256 x f BRT V - 0.4V CC ...
Page 12
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications Fixed-Frequency Step-Up Controller The MAX8790’s fixed-frequency, current-mode, step-up controller automatically chooses the lowest active FB_ voltage to regulate the feedback voltage. Specifically, the difference between the lowest FB_ ...
Page 13
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications At startup, the MAX8790 checks each FB_ pin to deter- mine if the respective current string is enabled. Each FB_ pin is internally pulled up with a 10µA ...
Page 14
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications clamped to a level set with the OV feedback input. When this elevated output voltage is applied to the undamaged strings, excessive voltage drop develops across the FB_ ...
Page 15
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications In digital dimming mode, the step-up controller and current source are directly turned on and off by the PWM signal. The current pulse magnitude, or full-scale current, is ...
Page 16
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications adequate for oscillator frequencies in the 166Hz < f < 500Hz range. The PLL frequency capture window is 0 PLL PLL The PLL ...
Page 17
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications Table 4. Component Suppliers SUPPLIER Murata Nichia Sumida Toshiba Vishay components for the typical applications circuit. Table 4 lists component suppliers. External component value choice is primarily dictated ...
Page 18
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications where 51mV is a scale factor based on slope compen- sation, and R is the current-sense resistor. To deter- S mine the minimum inductor value, the R temporarily ...
Page 19
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications Output Capacitor Selection The total output voltage ripple has two components: the capacitive ripple caused by the charging and discharging on the output capacitor, and the ohmic ripple ...
Page 20
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications Input Capacitor Selection The input capacitor (C ) filters the current peaks drawn IN from the input supply and reduces noise injection into the IC. A 10µF ceramic ...
Page 21
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications EXT SHDN TO V MAX8790 FB1 FB2 FB3 FB4 FB5 FB6 Figure 6. Startup Circuit with Large Capacitors on LED Strings PCB Layout Guidelines ...
Page 22
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications Pin Configuration TOP VIEW CCV 17 ISET 18 MAX8790ETP+ FSET 19 CPLL 4mm x 4mm THIN QFN ...
Page 23
Six-String White LED Driver with Active Current Balancing for LCD Panel Applications (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.) ______________________________________________________________________________________ Package Information PACKAGE OUTLINE, ...
Page 24
... 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 ____________________ 24 © 2006 Maxim Integrated Products ...