TK11840 DCDC Controller, 1ch, Step-up, Inductive DCDC1ch Feature Adjustable output voltage External Power Transistor High speed adjustable OSC (Up to 1MHz) (1MHz) Internal soft start circuit Internal timer-latch type short circuit detection Totem-pole type output whose current is adjustable(correspond to NPN transistor) (npn) On/Off control available Low Quiescent Current (5mA@no load) (5mA) Small 8 Pin SOT23L-8 package (SOT23L-8) VOP=1.8~10V Operating Voltage Range VOP=1.8 to 10V Operating Temp Range TOP=-20 to +85C TOP=-20~+85C PD=400mW Power Dissipation PD=400mW Characteristics Part Name TK11840 Number of DCDC 1ch fOSC Up to 1MHz Number of LED in serial connection 2 LED or more ILED.MAX Depends on external transistor Ordering Guide, Marking Part Name TK11840 Page 118 Ordering Name TK11840LTL-GH Marking D40 Description Order Size TK11840: Part Name 1,300 L: SOT23L-8 Package pcs. TL: Tape&Reel, Left /Reel -GH: PB-Free&Halogen Free 2010 AUTUMN Block Diagram, Standard Application 11 Error Amplifier EaIn 1 8 FB 0.5V PWM Comparator Soft Start Short Circuit Protection DCDC Controller 7 OSC SCP 2 Oscillator 6 GND VCC 3 1.3V Reference Voltage Supply Output Drive Control Circuit 5 Out BR/CTL 4 In VIn Out COut CIn 1 EaIn FB 8 W-LED CFB 2 SCP OSC 7 CSCP 3 Ct VCC Rt GND 6 R1 4 BR/CTL Out 5 Rb CTL 2010 AUTUMN Page 119