SEMICONDUCTOR INTEGRATED CIRCUITS

Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor

Jinguang Jiang, Fei Huang and Zhihui Xiong

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 Corresponding author: Jinguang Jiang, E-mail: jgjiang09@aliyun.com

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Abstract: A current-mode PWM buck DC-DC converter is proposed. With the high-accuracy on-chip current sensor, the switching frequency can be selected automatically according to load requirements. This method improves efficiency and obtains an excellent transient response. The high accuracy of the current sensor is achieved by a simple switch technique without an amplifier. This has the direct benefit of reducing power dissipation and die size. Additionally, a novel soft-start circuit is presented to avoid the inrush current at the starting up state. Finally, this DC-DC converter is fabricated with the 0.5 μ m standard CMOS process. The chip occupies 3.38 mm2. The accuracy of the proposed current sensor can achieve 99.5% @ 200 mA. Experimental results show that the peak efficiency is 91.8%. The input voltage ranges from 5 to 18 V, while a 2 A load current can be obtained.

Key words: DC-DCswitching frequencycurrent sensorsoft-startwide load range



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Fig. 1.  Block diagram of the proposed PWM DC-DC buck converter.

Fig. 2.  The proposed current sensor.

Fig. 3.  (a) ON-state of current sensor. (b) Off-state of current sensor.

Fig. 4.  The controller of switching frequency selection.

Fig. 5.  The proposed soft-start circuit.

Fig. 6.  Schematic of the oscillator.

Fig. 7.  The proposed slope compensation circuit.

Fig. 8.  (a) Chip microphotograph. (b) Experimental board.

Fig. 9.  Simulation results of the current sensor.

Fig. 10.  Frequency selection under different load conditions.

Fig. 11.  The waveform of different oscillation frequencies.

Fig. 12.  Soft-start time with various capacitors.

Fig. 13.  (a) 1500 to 100 mA load step. (b) 100 to 1500 mA load step.

Fig. 14.  Measured input voltage range.

Fig. 15.  Measured soft-start waveform.

Fig. 16.  Measured load transient of 1400 mA step.

Fig. 17.  Measured efficiency.

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Table 1.   Switching frequency under different loads.

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Table 2.   Soft-start time.

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Table 3.   Performance list and comparison with other designs.

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    Received: 21 October 2014 Revised: Online: Published: 01 May 2015

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      Jinguang Jiang, Fei Huang, Zhihui Xiong. Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor[J]. Journal of Semiconductors, 2015, 36(5): 055005. doi: 10.1088/1674-4926/36/5/055005 J G Jiang, F Huang, Z H Xiong. Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor[J]. J. Semicond., 2015, 36(5): 055005. doi: 10.1088/1674-4926/36/5/055005.Export: BibTex EndNote
      Citation:
      Jinguang Jiang, Fei Huang, Zhihui Xiong. Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor[J]. Journal of Semiconductors, 2015, 36(5): 055005. doi: 10.1088/1674-4926/36/5/055005

      J G Jiang, F Huang, Z H Xiong. Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor[J]. J. Semicond., 2015, 36(5): 055005. doi: 10.1088/1674-4926/36/5/055005.
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      Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor

      doi: 10.1088/1674-4926/36/5/055005
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      Project supported by the National Natural Science Foundation of China (No.41274047), the Natural Science Foundation of Jiangsu Province (No.BK2012639), the Science and Technology Enterprises in Jiangsu Province Technology Innovation Fund (No.BC2012121), and the Changzhou Science and Technology Support (Industrial) Project (No.CE20120074).

      More Information
      • Corresponding author: E-mail: jgjiang09@aliyun.com
      • Received Date: 2014-10-21
      • Accepted Date: 2014-12-05
      • Published Date: 2015-01-25

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