AN015 AIC | Alldatasheet
Document overview
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Technical content
The leakage resistance can be calculated from the resistivity of insulation, ρ,since the geometry is known. We substitute d Ae and A dr for C and RLEAK and derive the result werd 1tan = from equation 9. Thus the loss tangent is independent of geometry and can be considered a material property associated with the insulator. That is, the ESR value strongly depends on the choice of insulation material. The effect of ESR Unfortunately, the effect of ESR will never disappear. Below the resonant frequency, a real capacitor will show a resistance in series with a capacitive reactance. The capacitor becomes a simple RC series combination. In some applications such as a DC/DC con verter, a capacitor is often exposed to a square wave of current. Ideally, this produces a triangular voltage across the part shown in figure 7. Figure 7. But to lead to some unusual result, the ESR will exhibit an ESR voltage drop. With the ESR, a small square wave adds in series with the triangle, the abrupt voltage change called an ESR jump. In some case, it can dominate over ripple during the design process. Even when LDO used , the ESR effect appears as the variation loading current applied. Tutorial example Switching mode power supply part As the IT market grows rapidly, the device power requirement is getting more and more complicated. Obvouusly, one trend is to use the switching mode power supply instead of conve ntional linear regulator, which betters the efficiency. This design example , as showm in figure 8 , provides an output voltage of 1.3V to 3.5V, which meets the VRM8.4 specification. It can deliver high current to a CPU V CORE load. According to the tight VRM transicent demand, the effect of ES R plays a significant role in the application.
AIC1570- Advanced PWM Switching and Dual Linear Controller IC!!! The AIC1570 combines a synchronous voltage mode controller with a low dropout linear regulator and a linear controller as well as the monitor ing and prote ction functions in this chip. The PWM controller regulates the microprocessor core voltage with a synchr onous rectified buck converter. The linear controller regulates power for the GTL bus and the linear reg ulator provides power for the clock driver circuit. An integrated 5 bit D/A converter that adjusts the core PWM output voltage from 2.1V to 3.5V in 0.1V increments and from 1.3V to 2.05V in 0.05V increments. The linear regulator uses an internal driver device to provide 2.5V±2.5%. The linea r controller drives with an external N -channel MOSEFET to provide 1.5V±2.5%.
Features
l Provides 3 Regulated Voltages for Microprocessor Core, Clock and GTL Power. l Simple Voltage-Mode PWM Control. l Dual N-Channel MOSFET Synchronous Driver. l Operates from +3.3V, +5V and +12V Inputs l Fast Transient Response. l Full 0% to 100% Duty Ratios. l ±1.0% Output Voltage for VCORE and ±2.0% Output Voltage Reference for VCLK and VGTL. l TTL Compatible 5-bit Digital-to-Analog Core Output Voltage Selection. Range from 1.3V to 3.5V. l Adjustable Current Limit without External Sense Resistor. l Microprocessor Core Voltage Protection against Shorted MOSFET. l Power Good Output Voltage Monitor. l Over-Voltage and Over-Current Fault Monitors. l 200KHz Free-Running Oscillator Programmable up to 350KHz