ZXSC310 LED DRIVER SOLUTION FOR LCD BACKLIGHTING DEVICE DESCRIPTION The ZXSC310 is a single or multi cell LED driver The ZXSC310 is a PFM DC-DC controller IC that drives designed for LCD backlighting applications. The input an external Zetex switching transistor with a very low voltage range of the device is between 0.8V and 8V. saturation resistance. These transistors are the best This means the ZXSC310 is compatible with single switching devices available for this type of conversion NiMH, NiCd or Alkaline cells, as well as multi-cell or enabling high efficiency conversion with low input LiIon batteries. voltages. The drive output of the ZXSC310 LED driver generates a dynamic drive signal for the switching transistor. The device features a shutdown control, resulting in a standby current less than 5A, and an output capable of driving serial or parallel LEDs. The circuit generates The circuit can start up under full load and operates constant power output, which are ideal for driving down to an input voltage of 0.8 volts. The solution single or multiple LEDs over a wide range of operating configuration ensures optimum efficiency over a wider voltages. These features make the device ideal for range of load currents several circuit configurations driving LEDs particularly in LCD backlight applications are possible depending on battery life versus for Digital Still cameras and PDAs. brightness considerations. The ZXSC310 is offered in the SOT23-5 package which, FEATURES when combined with a SOT23 switching transistor, generates a high efficiency small size circuit solution. 94% efficiency The IC and discrete combination offers the ultimate Minimum operating input voltage 0.8V cost Vs performance solution for LED backlight applications. Maximum operating input voltage 8V Standby current less than 5A Programmable output current Series or parallel LED configuration Low saturation voltage switching transistor TYPICAL APPLICATIONS CIRCUIT SOT23-5 package APPLICATIONS LCD backlights: V =3.3V/5V IN Digital still camera PDA Mobile phone V CC V DRIVE LED flashlights and torches S TDN I SENSE White LED driving Gnd Multiple LED driving ORDERING INFORMATION DEVICE REEL TAPE QUANTITY WIDTH PER REEL SIZE ZXSC310E5TA 180mm 8mm 3000 DEVICE MARKINGS C310 Package SOT23-5 ISSUE 3 - SEPTEMBER 2007 1 SEMICONDUCTORSZXSC310 ABSOLUTE MAXIMUM RATINGS: Supply Voltage -0.3 to 10V Maximum Voltage other pins -0.3 to VCC+0.3V Power Dissipation 450mW Operating Temperature -40 to 85 C Storage Temperature -55 to 150C ELECTRICAL CHARACTERISTICS: Test conditions unless otherwise stated: V =1.5V, T =25 C CC AMB Symbol Parameter Conditions Min Typ Max Units (1) Efficiency 94 % V Recommended supply 0.8 8 V CC voltage range V Minimum startup and I =-600A V =0.7V 0.8 0.92 V CC(min) DRIVE , DRIVE operating voltage I =-600A, V =0.7V, 0.9 DRIVE DRIVE (3) T =-10C AMB (2) I Quiescent current V V (enabled) 0.2 mA Q EN = CC V 0V (standby) 510 A EN = I Base drive current V =0.7V, V =0V 1.5 3.5 mA VDRIVE DRIVE ISENSE (3) I Supply current V =0.7V, V =0V 2 4 mA CC DRIVE ISENSE V High level drive voltage V =0V, I =-0.5mA V V V VDRIVE(high) ISENSE VDRIVE CC CC -0.3 V Low level drive voltage V = 50mV, I =5mA 0 0.2 V VDRIVE(low) ISENSE VDRIVE V Device enabled 0.7 V STDN(high) V Device in standby mode 0.15 V STDN(low) I Enable input current -1 1 A STDN V Output current reference 14 19 24 mV ISENSE voltage (threshold) (2) T I voltage temp co. 0.4 %/C CVISENSE SENSE I I input current V =0V 0 -30 -65 A ISENSE SENSE ISENSE T Discharge Pulse Width 1.2 1.7 3.2 s DRV OPERATING CONDITIONS Symbol Parameter Conditions Min Typ Max Units F Recommended operating 200 kHz OSC (4) frequency (1) Application dependent, see reference designs (2) These parameters guaranteed by Design and characteristics (3) Total supply current =I +I , see typical characteristics Q VDRIVE (4) Operating frequency is application circuit dependent. See applications section. ISSUE 3 - SEPTEMBER 2007 2 SEMICONDUCTORS