ZXSC300 Datasheet | Zetex Semiconductors

DESCRIPTION The ZXSC300 is a single or multi cell LED driver designed for applications where step-up voltage conversion from very low input voltages is required. These applications mainly operate from single 1.5V or 1.2V battery cells. The circuit generates constant current pulses that are ideal for driving single or multiple LED’s over a wide range of operating voltages. The ZXSC300 is a PFM controller IC that drives an external Zetex switching transistor with a very low saturation resistance. These transistors are the best switching devices available for this type of switching conversion enabling high efficiency conversion with input voltages below 1 volt. The drive output of the ZXSC controller generates a dynamic drive signal for the switching transistor. The circuit can start up under full load and operates down to an input voltage of 0.8 volts. The solution configuration ensures optimum efficiency over a wide range of load currents, several circuit configurations are possible depending on battery life versus brightness considerations. The ZXSC300 is offered in the SOT23-5 package which, when bined with a SOT23 switching transistor, generates a high efficiency small size circuit solution. The IC and discrete bination offers the ultimate cost vs performance solution for single cell LED driving applications. FEATURES - - - - - 94% efficiency Minimum operating input voltage 0.8V Fixed output current Low saturation voltage switching transistor SOT23-5 package ORDERING INFORMATION DEVICE ZXSC300E5 Package SOT23-5 Partmarking C300 TYPICAL APPLICATION CIRCUIT VBATT L1 100µH U1 Vcc Vdrive Isense Gnd ZXSC300 Q1 FMMT617 LED1 WHITE LED R1 0.33R ISSUE 1 - JUNE 2001 1 ABSOLUTE MAXIMUM RATING Supply Voltage Maximum Voltage Other Pins Power Dissipation -0.3 to 10V -0.3 to VCC+0.3V 450m W Operating Temperature Storage Temperature -40 to 85°C -55 to 125°C ELECTRICAL CHARACTERISTICS: Test conditions unless otherwise stated: VCC=1.5V, TAMB=25°C Symbol η V CC...