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1 2A 3MHz 6V Synchronous Buck Converter KX2126 DESCRIPTION The KX2126is a high efficiency synchronous, buck DC/DC converter.

Its input voltage range is from 2.6V to 6V and provides an adjustable regulated output voltage from 0.6V to Vin while delivering up to 2A of output current. The internal synchronous switches increase efficiency and eliminate the need for an external Schottky diode. It runs at a fixed 3MHz frequency, which allows the use of small inductor with L2000V Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability. 深圳市科信威电子有限公司 科芯微电子(香港)有限公司 Tel: 0755-27805565 Fax: 0755-27897289 http://www.szkxw.com ROHS

3 RECOMMENDED WORK CONDITIONS Parameter Value Input Voltage Range Max. 6V Operating Junction Temperature(Tj) -20°C C125°C ELECTRICAL CHARACTERISTICS (VIN=5V, TA=25°C) Symbol Parameter Conditions Min Typ Max Unit VDD Input Voltage Range 2.6 6.0 V UVLO Input Under Voltage Lockout Increase Vin 2.1 2.2 V Vref Feedback Voltage Vin=5V, Ven=5V 0.588 0.6 0.612 V Ifblk Feedback Leakage current 0.01 0.1 uA Iq Quiescent Current Active, Vfb=0.65V, No Switching

30 uA Shutdown 0.1

1 uA LnReg Line Regulation Vin=2.7V to 5.5V 0.04 %/V LdReg Load Regulation Iout=0.1 to 2A 0.15 %/A Fsoc Switching Frequency 2.4

3 3.6 MHz RdsonP PMOS Rdson Isw=200mA

100 120 mohm RdsonN NMOS Rdson Isw=200mA

80 100 mohm Ilimit Peak Current Limit 2.5

3 A Iswlk SW Leakage Current Vout=5.5V, EN=GND

10 uA Venh, Vmdh EN/MODE High Threshold 1.5 V Venl, Vmdl EN/MODE Low Threshold 0.4 V Ienlk, Imdlk EN/MODE Leakage Current EN=MODE=GND

1 uA Rdischarge Discharge Resistance EN=GND

180 300

450 Ohm TYPICAL PERFORMANCE CHARACTERISTICS (Vin=3.6V, L=1uH, Cin=10uF, Cout=10uF, TA=25°C, unless otherwise stated) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0 0.5 1.0 1.5 2.0 2.5 Efficiency Iout(A) Efficiency at Vout=3.3V VIN=3.7V VIN=4.2V VIN=5.0V 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00% 0.0 0.5 1.0 1.5 2.0 2.5 Efficiency Iout(A) Efficiency at Vout=1.8V VIN=5.0V VIN=3.0V VIN=3.6V 深圳市科信威电子有限公司 科芯微电子(香港)有限公司 Tel: 0755-27805565 Fax: 0755-27897289 http://www.szkxw.com ROHS

4 Switching waveform Vin=3.6V, Vout=1.2V Iout=0A Switching waveform Vin=3.6V, Vout=1.2V Iout=0.7A Switching waveform Vin=5V, Vout=3.3V, Iout=0A Switching waveform Vin=5V, Vout=3.3V, Iout=0.5A 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00% 0.0 0.5 1.0 1.5 2.0 2.5 Efficiency Iout(A) Efficiency at Vout=1.2V VIN=3.0V VIN=3.6V VIN=5.0V 1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85 1.9 1.95

2 0 0.5

1 1.5

2 2.5 Vout (V) Iout(A) Load Regulation at Vout=1.8V VIN=3V VIN=3.6V VIN=5V VOUT SW I_inductor SW VOUT I_inductor SW VOUT I_inductor SW VOUT I_inductor 深圳市科信威电子有限公司 科芯微电子(香港)有限公司 Tel: 0755-27805565 Fax: 0755-27897289 http://www.szkxw.com ROHS

5 Load Transient Vin=3.6V, Vout=1.2V, Iout=0.2A/1A Load Transient Vin=3.6V, Vout=1.8V, Iout=0.2A/1.5A FUNCTIONAL DECRIPTIONS The KX2126 high efficiency switching regulator is a small, simple, DC-to-DC step-down converter capable of delivering up to 2A of output current. The device operates in pulse-width modulation (PWM) at 3MHz from a 2.6V to 5.5V input voltage and provides an output voltage from 0.6V to VIN, making the KX2126 ideal for on-board post-regulation applications. An internal synchronous rectifier improves efficiency and eliminates the typical Schottky free-wheeling diode. Using the on resistance of the internal high-side MOSFET to sense switching currents eliminates current-sense resistors, further improving efficiency and cost. Loop Operation KX2126uses a PWM current-mode control scheme. An open-loop comparator compares the integrated voltage-feedback signal against the sum of the amplified current-sense signal and the slope compensation ramp. At each rising edge of the internal clock, the internal high-side MOSFET turns on until the PWM comparator terminates the on cycle. During this on-time, current ramps up through the inductor, sourcing current to the output and storing energy in the inductor. The current mode feedback system regulates the peak inductor current as a function of the output voltage error signal. During the off cycle, the internal high-side P-channel MOSFET turns off, and the internal low-side N-channel MOSFET turns on. The inductor releases the stored energy as its current ramps down while still providing current to the output. Current Sense An internal current-sense amplifier senses the current through the high-side MOSFET during on time and produces a proportional current signal, which is used to sum with the slope compensation signal. The summed signal then is compared with the error amplifier output by the PWM comparator to terminate the on cycle. Current Limit There is a cycle-by-cycle current limit on the high-side MOSFET. When the current flowing out of SW exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. KX2126utilizes a frequency fold-back mode to prevent overheating during short-circuit output conditions. The device enters frequency fold-back mode when the FB voltage drops below 200mV, limiting the current to IPEAK and reducing power dissipation. Normal operation resumes upon removal of the short-circuit condition. Soft Start KX2126has a internal soft-start circuitry to reduce supply inrush current during startup conditions. When the device exits under-voltage lockout (UVLO), shutdown mode, or restarts following a thermal-overload event, the l soft-start circuitry slowly ramps up current available at SW. SW VOUT I_inductor I_inductor VOUT SW 深圳市科信威电子有限公司 科芯微电子(香港)有限公司 Tel: 0755-27805565 Fax: 0755-27897289 http://www.szkxw.com ROHS