QX Micro Devices QX2303L50TO

The QX2303 Series are PFM step-up DC-DC converters with high efficiency, low ripple and high operation frequency. The QX2303 Series need only four external components to realize step-up conversion from low input battery voltage to the voltage needed, and they are applied to one to four battery-cells application. The QX2303 Series adopt low dissipation and high performance reference circuit, with trimming technique in manufacture, which ensure high precision and low temperature drift of the output voltage. The precision of output voltage precede ±2.5%, and the highest efficiency is 89%. The QX2303 Series have four package types: SOT23, SOT23-5, SOT89-3 and TO-92. For SOT23-5 package, an enable pin “EN” is provided so that the operation state of the converter can be controlled. When EN is low, the converter is in power saving mode, which decreases power dissipation to the minimum. The QX2303 Series are step-up DC-DC converters with boost structure and PFM control mode. The QX2303 Series need only an inductor, a schottky diode, an input capacitor and an output capacitor to provide a 2.5~5.0V low noise output voltage. The converter has many built-in function blocks including Output Voltage Feedback And Trimming Network, Startup Circuit, Oscillator, Reference Voltage Circuit, PFM Controller, Over Current Protection and Power MOS. The core circuit of QX2303 is the PFM Controller. This module controls the power MOS to provide the constant output voltage according to the input voltage, the load signal and the current signal. In the PFM Control system, the oscillation frequency and the pulse width are fixed, and the steady output voltage are realized by controlling the ON-time of power MOS in an oscillation cycle according to the ratio of input/output voltage and the load. Oscillator provides reference oscillation frequency and fixed pulse width. Reference Voltage circuit provides steady reference voltage. With internal trimming technique, the output voltage accuracy can be ±2.5%. With temperature compensation technique used in the Reference Voltage circuit, the temperature drift of the output voltage is less than 100ppm/°C. Error Amplifier with high gain ensures the steady of the output voltage under different input voltages and load currents. In order to decrease the ripple and noise of the output voltage, the Error Amplifier adopts schmitt comparator structure, which has rapid response. The inductor and the schottky diode will sharply influence the conversion efficiency, and the capacitors and inductor will influence ripple of output voltage, so choosing a suitable inductor, capacitor and schottky diode can acquire high conversion efficiency, low ripple and low noise.

• 300KHz Maximum Operating Frequency
• 2.5V to 5.0V Output Voltage With 0.1V step
• Low Start-up Voltage: 0.8V at 1mA
• ±2.5% Output Voltage Accuracy
• Up to 89% Efficiency
• Output Current: 300mA at 2.5V Input, 3.3V Output voltage
• Low Ripple and Low Noise
• Four external components needed only

• One to Three Cell Battery Devices
• LED Lamp, LED Flashlight
• Portable Instruments Such As Electronic Dictionary, VCR, PDA And So On