| With the rapid development of the microelectronics and semiconductor technology, the power management chips have been widely used in the field of communication networks, computers, automotive electronics and so on. In recent years, the characteristics such as the high-voltage, high-efficiency, quick response and small volume of the integrated DC-DC converters have made the application of the power management chips become a new trend. This paper is mainly focused on the study of the inductive DC-DC. The key technology of DC-DC and its theoretic analysis are presented and certain technologies have been deeply researched such as the high-voltage, high-efficiency, rapid response and self adaptive technology. By connecting with different high-voltage converters under different application environments, two kinds of internal reference circuits in IC chips under different high-voltage application environments are designed, thus realizing the applications and the internal regulation under two different high voltage conditions. Meanwhile, considering the three main factors:static losses, switching losses and conduction losses which affects the DC-DC efficiency, corresponding solutions are proposed to promote the DC-DC efficiency systematically. Secondly, aiming at the two different DC-DC control loops, two fast transient response circuits are designed to realize the requirements of the fast transient response under different application scenarios. Thirdly, in order to reduce the overcharge phenomenon during the charging process, a kind of soft-start circuit is proposed to protect the whole system. Finally, results of the above research are applied to DC-DC converters of different application conditions according to different scenarios in order to promote the performance of the chips and eventually adapt the market requirements.The main research work and contributions are as follows:1. A kind of fast start-up and high precision voltage reference circuit without trimming adjustment is proposed, aiming at the wide range of input voltage. By using the characteristics of the Zener diode, a kind of TTLBUFFER with simple topology and fast start-up is designed in front of the voltage reference. The TTLBUFFER not only widens the range of the input voltage but also increases the precision of the voltage reference. The adoption of fast start-up circuit greatly accelerates the start-up speed of the reference circuit.2. A novel on-chip high to low voltage power conversion circuit solution is achieved against power dissipation of high-voltage IC.This solution makes use of the gap principle and generates an adjustable output voltage reference, other than the traditional on-chip power convert solution. The Push-Pull output method is also used for increasing the load capacity of the reference power, therefore it can be used as the internal power of high voltage IC and then realizes the high to low voltage conversion. The high order temperature compensation circuit is also designed to ensure the precision of the output voltage.3. A filter-based lossless inductor current sensing circuit is proposed in this paper to reduce static power dissipation. By using the design of an ultra-wide bandwidth trans-conductance amplifier, the DC-DC can work under higher switching frequencies, thus eliminating the effect to the precision of the sampling current from the time constant of the inductors and capacitors. Meanwhile, the trans-conductance amplifier designed can realize the I/V conversion of sampling current, and then input it into the PWM comparator through AC-coupling. Compared with the traditional current sampling circuit, this circuit has no DC loss and can be used in high power output IC.4. Targeted on the discontinuous current mode (DCM) of the Buck switching regulator, a kind of novel load current detection circuit is proposed. The synchronous gate driving signal which almost changes synchronously with load current as the current sampling signal is designed to realize the average load current detection, which can effectively increase the efficiency of the switching power supply within the range of the load.5. The inductor current backflow phenomenon occurs when the Buck-type DC-DC works under the discontinuous current mode (DCM). This condition will greatly lower the efficiency of the system. In consideration of this problem, a kind of zero-cross detection circuit is designed. By using the disordered resistance to counteract the turn-off delay, the fast shutdown of the Synchronous Transistor will be realized and the probability of the current back flow will be reduced.6. A kind of novel non-linear loop control solution is proposed, aiming at the problem of high output voltage ripple and unfixed frequency in nonlinear control loops. The solution views the main comparator, driving transistor, power transistor and the inductor-capacitor filter network in the DC-DC converter as a ring oscillator. The RC network is designed near the main comparator to widen the stable frequency range, and to eliminate the instability caused by the parasitic resonance in the loop ring. By adding the FLL to the driving and the main comparators, the frequency can be locked to a fixed reference frequency to eliminate the phenomenon of frequency instability; therefore the fast load transient response will be realized.
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