The hottest power supply meeting amdk8 low power m

2022-08-05
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Power supply meeting amd K8 low power mobile processor specification

Abstract: this application note describes a two-phase, synchronous rectifier buck regulator that fully meets amd K8 low power mobile processor specification. It includes the detailed circuit working principle, circuit diagram, component list and test data of a 1.2V, 27.3a reference design

this application note describes a two-phase, synchronous rectifier buck regulator that fully meets the AMD K8 low power mobile processor specification using max1937

this design uses the standard K8 vid platform, which adds a -100mv offset to the selected vid voltage. An active migration method achieves the required -100mv migration. The fixed deviation or voltage specified in this application is set at 50mV

the details, schematic diagram and complete component list of the power supply of the active offset circuit are listed below. A reference design and test data of 1.2V and 27.3a are also given below

for details of two-phase, synchronous rectifier step-down regulator (voltage positioning, etc.), please refer to the data of max1937-max1939

active offset

Figure 1 shows the active offset circuit, which is essentially a 1mA precision current source. The circuit includes R51, R52, R53, R54, R55 and operational amplifier lmx321 (U2). The circuit receives a 2V input from the reference voltage (pin 12) of the max1937 and maintains a 2V voltage of the polarity shown in the figure on the 2K resistor R55. Thus, 1mA electric current is generated in the resistance, and the current generates a negative offset of -100mv through 100 resistor R8 connected to max1937 FB pin (14 pin)

figure 1 Active offset circuit

the output impedance of the above circuit is much greater than the load resistance (100 in this example), so its influence on the circuit can be ignored. For an offset of -100mv, the accuracy of the above circuits depends on the 2V reference voltage (13mv varying from 0 C to 85 C), the 2K (1%) resistor r5a and the 100 (1%) FB resistor R8. The offset voltage is given by the pendulum energy: the following formula:

the maximum error of the offset voltage is 2.6mv by substituting the component parameters under the worst operating conditions into the above formula. Table 1 shows the selected vid code and the corresponding actual output voltage value at no-load to illustrate the performance of the dynamic offset circuit. Table 2 lists 1 The load adjustment parameters of 2V and 35W power supply are greatly deformed during tightening

table 1 Although the optical properties of the material with -100mv offset are the most important, the wettability and good permeability of the material are extremely important to protect the tear film on the cornea and the health of the eyes. The ID code and the corresponding actual output voltage

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