R1204x Series Step-up DC/DC Converter with Shutdown Function No. EA-284-200901 OUTLINE The R1204x is a low supply current PWM step-up DC/DC converter. Internally, a single IC consists of an NMOS FET, an oscillator, a PWM comparator, a voltage reference unit, an error amplifier, a current limit circuit, an under voltage lockout circuit (UVLO), an over-voltage protection circuit (OVP), a soft-start circuit, a maximum duty cycle limit circuit, and a thermal shutdown protection circuit. By simply using an inductor, a resistor, capacitors and a diode as external components, a high-efficiency step-up DC/DC converter can be easily configured. As protection functions, the IC contains a thermal shutdown protection circuit, a current limit circuit, an OVP circuit, and an UVLO circuit. A thermal shutdown circuit detects overheating of the ICs and stops the operation to protect it from damage. A current limit circuit limits the peak current of Lx, and an OVP circuit detects the over voltage of output, and an UVLO circuit detects the low input voltage. The R1204x provides the R1204xxxA/D/G/H versions, which are optimized for serial driving of white LEDs with constant current, and the R1204xxxB/C/E/F versions, which are optimized for constant voltage driving. Among the R1204xxxB/C/E/F versions, only the R1204xxxC/F versions are equipped with PWM/VFM auto-switching controls. The LED current can be determined by the value of current setting resistor. The brightness of the LEDs can be quickly adjusted by applying a PWM signal (200 Hz to 300 kHz) to the CE pin. The R1204x is available in DFN(PLP)1820-6 and TSOT-23-6 packages. FEATURES Input Voltage Range .......................................... 2.3 V to 5.5 V Supply Current .................................................. Typ. 800 A Standby Current ................................................ Max. 5 A Feedback Voltage ............................................. 0.2 V 10 mV (R1204xxxxA/D) 0.4 V 10 mV (R1204xxxxG/H) V 15 mV (R1204xxxxB/C/E/F) Lx Current Limit Function .................................. Min. 700 mA Over Voltage Protection .................................... 23 V, 33 V, 42 V Oscillator Frequency ......................................... Typ. 1.0 MHz (R1204xxxxA/B/C/G) Typ. 750 kHz (R1204xxxxD/E/F/H) Maximum Duty Cycle ........................................ Min. 91% (R1204xxxxA/B/C/G) Min. 92% (R1204xxxxD/E/F/H) FET ON Resistance .......................................... Typ. 0.8 UVLO Function Thermal Protection Function LED Dimming Control for R1204xxxxA/D ......... by external PWM signal (200 Hz to 300 kHz frequency) Packages .......................................................... DFN(PLP)1820-6, TSOT-23-6 Recommended Bypass Capacitor .................... 1.0 F APPLICATIONS Constant voltage power source for hand-held equipment OLED power supply for hand-held equipment White LED driver for hand-held equipment 1 R1204x No. EA-284-200901 SELECTION GUIDE The package type, the OVP detector threshold, the feedback voltage and the PWM//VFM auto-switching control are user- selectable options as described below. Selection Guide Product Name Package Quantity per Reel Pb Free Halogen Free R1204Kxy2z-TR DFN(PLP)1820-6 5,000 pcs Yes Yes R1204Nxy3z-TR-FE TSOT-23-6 3,000 pcs Yes Yes x: OVP Detector Threshold 1: 23 V 2: 33 V 3: 42 V y: Current Limit 1: Typ. 900 mA z: Feedback Voltage, Oscillator Frequency, PWM/VFM Auto-Switching Control PWM/VFM z Feedback Voltage Oscillator Frequency Auto-Switching Control A Typ. 0.2 V No B Typ. 1 V Typ. 1 MHz No C Typ. 1 V Yes D Typ. 0.2 V No E Typ. 1 V Typ. 750 kHz No F Typ. 1 V Yes G Typ. 1 MHz Typ. 0.4 V No H Typ. 750 kHz 2