R1240x Series 1.2 A, 30 V Step-Down DC/DC Converter NO.EA-190-170609 OUTLINE The R1240x is a CMOS-based Step-down DC/DC converter with internal Nch high side Tr. (0.35 ), which can provide the maximum 1.2 A output current. The ICs consists of an Oscillator, a PWM control circuit, a Reference Voltage unit, an Error amplifier, phase compensation circuits, a slope circuit, a s-ofsttart circuit, protection circuits, internal voltage regulators, and a switch for boot strap circuit. The ICs can make up a Step- Down DC/DC Converter with the following external components: an inductor, resistors, a diode, and capacitors. The R1240x is a current mode operating type DC/DC converter which does not require external current sense resistor, and i tworks high speed response time, high efficiency and compatible with ceramic capacitors. Oscillator frequency is internally set at 1.25 MHz. As a protection function, it has cycle by cycle peak current limit function, short protection function, thermal shutdown function and UVLO. There are two types for short protection, A version has latch protection function with 2m s delay time, and B version has fold-back protection function that keep operating at short condition with lower operating frequency and limiting the Lx current. FEATURES Operating Voltage 4.5 V to 30 V Internal Nch MOSFET Driver Typ. RON = 0.35 Adjustable Output Voltage with External Resistor 0.8 V to 15 V Feedback Voltage 0.8 V 1.5% Peak Current Limit Function Typ. 2.0 A UVLO Function Operating Frequency 1.25 MHz (Ver. B: 310 kHz, Fold-back Condition) Short Protection for Output Ver. A: Latch with 2 ms delay or Ver. B: Fold-back Ceramic Capacitor Compatible Stand-by Function Typ. 0 A Package SOT-23-6W, DFN(PLP)2527-10 APPLICATIONS Digital Home Appliances: Digital TVs, DVD Players OA Equipment: Printers, Fax Hand-held Communication Equipment, Cameras, VCRs, Camcorders Battery-powered Equipment 1 R1240x NO.EA-190-170609 SELECTION GUIDE In the R1240x, the Package, type of short protection (Latch or Fold- back) can be selected at the users request. Selection Guide Product Name Package Quantity per Reel Pb Free Halogen Free DFN(PLP)2527-10 5,000 pcs Yes Yes R1240K003-TR SOT-23-6W 3,000 pcs Yes Yes R1240N001-TR-FE : Designation of Optional Function at off state are options as follows. (A ) Latch Type protection (B ) Fold-back Type protection BLOCK DIAGRAM VIN Thermal Shutdown 5V CE UVLO Regulator Regulator BST Shutdown SETPULSE Oscillator S D (1250kHz/3 10kHz) Lx VFB MAXDUTY R - Reference - + + Soft Start 0.8V Circuit(0.4msec) Limit Latch Current Slope Circuit (2msec) Circuit (Ver.A only) Peak Current GND Limit Circuit R1240x Block Diagram 2