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MAX8901B Dataheets PDF



Part Number MAX8901B
Manufacturers Maxim Integrated Products
Logo Maxim Integrated Products
Description Highest Efficiency Supply
Datasheet MAX8901B DatasheetMAX8901B Datasheet (PDF)

19-0865; Rev 0; 8/07 Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package www.datasheet4u.com KIT ATION EVALU E L B AVAILA General Description ♦ High Efficiency, Up to 91% ♦ 2.6V to 5.5V Input Voltage Range ♦ Fixed-Frequency Operation Features MAX8901A/MAX8901B The MAX8901A/MAX8901B step-up converters drive from two to six series-connected white LEDs (WLEDs) with constant current to provide uniform WLED intensity for LCD backlighting in cell phones, PDAs, and other.

  MAX8901B   MAX8901B


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19-0865; Rev 0; 8/07 Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package www.datasheet4u.com KIT ATION EVALU E L B AVAILA General Description ♦ High Efficiency, Up to 91% ♦ 2.6V to 5.5V Input Voltage Range ♦ Fixed-Frequency Operation Features MAX8901A/MAX8901B The MAX8901A/MAX8901B step-up converters drive from two to six series-connected white LEDs (WLEDs) with constant current to provide uniform WLED intensity for LCD backlighting in cell phones, PDAs, and other handheld devices. The MAX8901_ operate at a fixed 750kHz (typ) switching frequency, allowing for tiny external components, and are optimized for the highest possible efficiency over the full 1-cell Li+/Li-Poly battery range. These converters use a single input (ON) to enable the IC and to control WLED intensity. The MAX8901A requires a direct PWM input to regulate WLED intensity with the WLED current proportional to the PWM duty cycle. The MAX8901B uses single-wire, serial-pulse dimming that reduces the WLED intensity in 32 linear steps. Full-scale WLED current for serial-pulse dimming is 24.75mA (MAX8901B, 0.75mA/step). The MAX8901_ features an internal soft-start to eliminate inrush currents during startup, input overvoltage protection, WLED overvoltage protection, and a shutdown mode with 0.01µA (typ) shutdown current. No WLED current is present in shutdown provided the WLED forward voltage is greater than the input supply voltage. Additional features include undervoltage lockout (UVLO) and thermal shutdown. The MAX8901_ are available in tiny 8-pin, 2mm x 2mm TDFN-EP packages (0.8mm max height). ♦ Supplies from 2 to 6 WLEDs with 1% LED Current Accuracy ♦ Flexible Dimming Control Direct PWM Dimming (MAX8901A) 32-Step, 1-Wire Serial Dimming (MAX8901B) ♦ Input Undervoltage Lockout ♦ Input Overvoltage Lockout ♦ WLED Overvoltage Protection (25V typ) ♦ 0.01µA (typ) Shutdown Current ♦ No WLED Current in Shutdown ♦ Internal Soft-Start and Thermal Shutdown Ordering Information PART MAX8901AETA+T MAX8901BETA+T PIN-PACKAGE 8 TDFN-EP* 2mm x 2mm 8 TDFN-EP* 2mm x 2mm PKG CODE T822-1 T822-1 TOP MARK +ABA +ABB Applications Display Backlight (from 2 to 6 WLEDs) Cellular Phones PDAs and Smartphones MP3 and Portable Media Players Portable Navigation Devices Digital Cameras Note: All devices are specified over the -40°C to +85°C operating temperature range. +Denotes a lead-free package. *EP = Exposed paddle. T = Tape and reel. Pin Configuration appears at end of data sheet. Typical Operating Circuits INPUT 2.6V TO 5.5V OUTPUT UP TO 25V INPUT 2.6V TO 5.5V 3 4 IN MAX8901A COMP LX 3 IN MAX8901B LX 4 OUTPUT UP TO 25V 7 OVP 1 7 COMP OVP 1 6 PWM DIMMING CONTROL 2 GND PGND 5 SERIAL-PULSE DIMMING CONTROL 6 GND PGND 5 ON EP CS 8 2 ON EP CS 8 ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. Highest Efficiency Supply for 2 to 6 Series WLEDs in a 2mm x 2mm TDFN Package MAX8901A/MAX8901B ABSOLUTE www.datasheet4u.com MAXIMUM RATINGS 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 IN to GND .................................................................-0.3V to +7V CS, COMP, ON to GND ...............................-0.3V to (VIN + 0.3V) OVP, LX to GND .....................................................-0.3V to +28V PGND to GND .......................................................-0.3V to +0.3V LX Current ..................................................................770mARMS Continuous Power Dissipation (multilayer board at +70°C) 8-pin, 2mm x 2mm TDFN (derate above +70°C by 11.9mW/°C) ..........................953mW 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 = VON = VOVP = 3.6V, VPGND = VGND = 0V, COMP, CS, and LX are unconnected, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Input Voltage Input Undervoltage Lockout Threshold Input Overvoltage Lockout Threshold Shutdown Input Current SYMBOL VIN VIN_UVLO VIN rising VIN falling VIN_OVLO ISHDN VIN rising VIN falling VON = 0V VCS = 0.55V, no load (not switching) TA = +25°C TA = +85°C MAX8901A MAX8901B VIN VDIODE 24 25 20 0.475 1.18 1.3 0.4 TA = +25°C TA = +85°C 40 0.5 0.5 500.0 0.01 0.1 1 0.50 1.


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