R1245x Series 1.2 A, 30 V Step-Down DC/DC Converter No. EA-269-201022 OUTLINE The R1245x is a CMOS-based Step-down DC/DC converter with internal N-channel high side Tr. The ON resistance of the built-in high-side transistor is 0.35 and the R1245x can provide the maximum 1.2 A output current. Each of the ICs consists of an oscillator, a PWM control circuit, a voltage reference unit, an error amplifier, a phase compensation circuit, a slope compensation circuit, a soft-start circuit, protection circuits, an internal voltage regulator, and a switch for bootstrap circuit. The ICs can make up a step-down DC/DC converter with an inductor, resistors, a diode, and capacitors. The R1245x is a current mode operating type DC/DC converter without an external current sense resistor, and realizes fast response and high efficiency. As an output capacitor, a ceramic type capacitor can be used with the R1245x. The options of the internal oscillator frequency are preset at 330 kHz for version A and B, 500 kHz for version C and D, 1000 kHz for version E and F, 2400 kHz for version G and H. As for protection, an Lx peak current limit circuit cycle by cycle, a thermal shutdown function and an under voltage lockout (UVLO) function are built in. Furthermore, there are two types for short protection, for A/C/E/G version, a latch protection function which makes the output latch off if the output voltage keeps lower than the set output voltage for a certain time after detecting current limit is built in, for B/D/F/H version, a fold-back protection function which changes the oscillator frequency slower after detecting short circuit or equivalent. As for the packages of the R1245x, HSOP-8E, DFN(PLP)2020-8, SOT23-6W are available. FEATURES Operating Voltage 4.5 V to 30 V Internal N-channel MOSFET Driver Typ. RON = 0.35 Adjustable Output Voltage with External Resistor 0.8 V or more Feedback Voltage and Tolerance 0.8 V 1.0% Peak Current Limit Typ. 2.0 A UVLO Function Released Voltage Typ. 4.0 V Operating Frequency 330 kHz (Ver. A/B), 500 kHz (Ver. C/D), 1000 kHz (Ver. E/F), 2400 kHz (Ver. G/H) Fold-back Protected Frequency 170 kHz (Ver. B/D), 250 kHz (Ver. F), 400 kHz (Ver. H) Latch Protection Delay Time Typ. 4 ms (Ver. A/C/E/G) Ceramic Capacitors Recommended for Input and Output. Stand-by Current Typ. 0 A Packages SOT-23-6W, DFN(PLP)2020-8, HSOP-8E 1 R1245x No. EA-269-201022 APPLICATIONS Digital Home Appliances: Digital TVs, DVD Players Office Equipment: Printers, Faxes 5V PSU or 2-cell or more Li-ion Battery Powered Communication Equipment, Cameras, VCRs, Camcorders High Voltage Battery-powered Equipment SELECTION GUIDE In the R1245x, the package, type of short protection (Latch or Fold-back), and the oscillator frequency can be selected with the users request. Selection Guide Product code Package Quantity per Reel Pb Free Halogen Free R1245S003 -E2-FE HSOP-8E 1,000 pcs Yes Yes R1245K003 -TR DFN(PLP)2020-8 5,000 pcs Yes Yes R1245N001-TR-FE SOT-23-6W 3,000 pcs Yes Yes : Designation of the oscillator frequency and the protection function option. Oscillator Latch Fold-back Symbol Frequency Protection Protection A 330 kHz B 330 kHz C 500 kHz D 500 kHz E 1000 kHz F 1000 kHz G 2400 kHz H 2400 kHz 2