CS1615 Micropower Step-up DC/DC Converters for White LEDS Features z Low Quiescent Current: z z z z z 20μA in Active Mode <1μA in Shutdown Mode Operates with VIN as Low as 1V Low VCESAT Switch: 250mV at 300mA Uses Small Surface Mount Components High Output Voltage: Up to 34V SOT23-5 Package Applications z LCD Bias z Handheld Computers z Battery Backup z Digital Cameras Description The CS1615 is micropower step-up DC/DC converters in a 5-lead SOT23-5 package. The CS1615 is designed for higher power systems with a 350mA current limit and an input voltage range of 1.2V to 15V, whereas the CS1615-1 is intended for lower power and single-cell applications with a 100mA current limit and an extended input voltage range of 1V to 15V. Otherwise, the two devices are functionally equivalent. Both devices feature a quiescent current of only 20μA at no load which further reduces to 0.5 μ A in shutdown. A current limited, fixed off-time control scheme conserves operating current. The 36V switch allows high voltage outputs up to 34V to be easily generated in a simple boost topology without the use of costly transformers. The CS1615’s low off-time of 400ns permits the use of tiny, low profile inductors and capacitors to minimize footprint and cost in space-conscious portable applications. Typical Application 1/5 CS1615 Absolute Maximum Ratings VIN, SHDN Voltage ........... ……………………….15V SW Voltage .............................................................. 36V B Voltage ................................................................. VIN Current into FB Pin ............................................ …1mA Junction Temperature ........................................... 125℃ Operating Temperature Range ……… – 40℃ to 85℃ Storage Temperature Range ............... – 65℃ to 150℃ Lead Temperature (Soldering, 10 sec) .................. 300℃ Package and Order Information Package Description 2/5 CS1615 Electrical Characteristics (TA=25℃,VIN=1.2V,VSHDN=1.2V unless otherwise noted) PARAMETER CONDITIONS MIN TYP UNITS 1.2 Minimum Input Voltage Quiescent Current MAX Not Switching 20 VSHDN=0V 1.205 FB Comparator Trip Point 1.23 30 μA 1 μA 1.25 V 8 FB Comparator Hysteresis V mV Output Voltage Line Regulation 1.2V<VIN<12V 0.05 0.1 %/V FB Pin Bias Current VFB=1.23V VFB>1V VFB<0.6V 30 80 nA Switch Off Time Switch VCESAT Switch Current Limit SHDN Pin Current ISW=300mA VSHDN=1.2V VSHDN=5V 300 400 ns 1.5 μS 250 350 350 400 mA 2 3 μA 8 12 μA 0.9 SHDN Input Voltage High V SHDN Input Voltage Low Switch Leakage Current Switch Off,VSW=5V mV 0.01 0.25 V 5 μA Pin Function Pin1(SW): Switch pin. This is the collector of the internal NPN power switch. Minimize the metal trace area connected to this pin to minimize EMI. Pin2 (GND): Ground. Tie this pin directly to the local ground plane. Pin3 (FB) : Feedback pin. Set the output voltage by selecting values for R1 and R2 R1=R2(VOUT/1.23-1) Pin4(SHDN): Shutdown Pin. Tie this pin to0.9V or higher to enable the device. Tie below 0.25V to turn off the device. Pin5(VIN) : Input Supply Pin. Bypass this pin with a capacitor as to the device as possible. 3/5 CS1615 Typical Performance Characteristics 4/5 CS1615 Typical Applications 5/5