Along with the double voltage architecture and the multi-processor board’s rapid popularization, possibly needs several processor voltage skeleton line including the simple application. Because each processor has own Canada and the power failure request, power source skeleton line sorting and the control turn a complex duty. The power source designers face the challenge is needs to consider that each processor fixed time with the voltage request, and buys in these requests in the overall system, guaranteed that designs finally satisfies all processor’s request.
Supplies power improper for the processor, will cause all sorts of questions, some not greatly serious, if MTBF (average trouble-free time interval) will reduce, some will be disastrous, like block system. In view of the fact that the available microprocessor’s multiplicity and you in proposed when power source sorting and control plan estimated the application challenge, uses the micro controller is may take, because it has the programmable ability. MSP430 is suitable this kind of application (Figure 1). This kind of high performance, low cost’s 16 RISC processor has several high grade simulation peripheral devices and a JTAG connection.
The control has the start pin (for instance majority ” brick bat ” on the DC/DC switch and low pressure drop voltage regulator’s start pin) the power source is merely uses GPIO (general I/O) the pin. If the power source has not enabled the function, then usually is the MOSFET online switch may use GPIO or the PWM signal control power source. Shown in Figure 1 the electric circuit to use the TPS725xx series low pressure drop manostat, provides 3.3V, 2.5V and the 1.8V three kind of voltages by an input direct-current power supply. These manostats have the start pin and the reset function. You may expand easily this electric circuit to have the random number voltage skeleton line. MSP430 monitors some controlled variable, by determined when starts each skeleton line. Regarding the power source sorting application, the variable which two most often control is the time and the voltage. When time for controlled variable, the controller starts the first skeleton line; In hereafter specific time, it start next skeleton line; In hereafter one time start next skeleton line, analogizes in turn again, is started up to until all skeleton lines.
MSP430 provides fixed time the sequence signal and the time controlled signal puts through the power source. If the voltage is the controlled variable, then the controller then starts the first voltage skeleton line and monitors its voltage through ADC the rise situation. When the first voltage skeleton line achieves the specific voltage level, the controller start next voltage skeleton line and monitors its voltage rise until to achieve the stipulation the voltage level. This time, the controller again start next voltage skeleton line and monitors its voltage rise. This process continued until the controller to start all voltage skeleton line. When serves as the voltage the controlled variable, the controller is not uses the GPIO signal is uses the PWM signal to take the start signal, regards designs whether to need the skeleton line track to decide. You may also concurrently use the voltage control with the timed control it.
In Figure 1, each low pressure drop manostat connects two MSP430 lines–A line uses in starting, another line uses in monitoring. When time for controlled variable, may carry on the surveillance through port 1 (GPIO); When voltage for controlled variable, may carry on the surveillance through port 6 (ADC). MSP430 also has the system reset end, and has the electricity saving input end. The code is simple, does not need how many programming experience. When time for controlled variable, must first do the matter is causes the MSP430 initialization and establishes the port and the timer, this operation needs 5 lines of codes (Table 1, this table may obtain from www.edn.com website). The next operation is uses the first timing separation to load ” the capture and comparison register zero ” (CCR0) and starts the timer. When the CCR0 value was equal to when timer’s value, the first voltage skeleton line is started. Afterward the use next timing separation loads CCR0, the timer replacement and starts. When CCR0 was equal to when timer’s value, the second voltage skeleton line is started. This operation carries on repeatedly, is started until all voltage skeleton line.
Once all skeleton lines are started, retards the return route then to start to begin using, guaranteed that on the low pressure drop manostat’s replacement pin has the time to achieve the specified voltage. The TPS725xx series has the drain electrode opening 100 millisecond reset function. When retards finished, MSP430 then inspects each manostat’s replacement line, guaranteed that all skeleton lines have achieved the specified voltage. If all skeleton lines have achieved the specified voltage, then MSP430 then issues the system reset order. When voltage for controlled variable, MSP430 (Table 2) the initialization only needs 5 lines of codes. The next operation will be according to 3V the ADC voltage reference on behalf of 3.3V, 2.5V and the 1.8V value loads in register R9, R10 and R11. The first article after the skeleton line starts, its output voltage receives the surveillance, occupies in the prescribed limit until it, this time the next skeleton line is started, and receives the surveillance. This operation carries on repeatedly, is started until all three skeleton lines. After all skeleton lines starts, uses in the detention return route which the manostat repositions starting, system reset.
After MSP430 puts through all voltage skeleton line and the executive system replacement, then enters the surveillance way. It (is decided through the replacement or the output pin by time for controlled variable or voltage for controlled variable) inspects the low pressure drop manostat’s output voltage continuously. If breaks down, MSP430 enters the wrong routine. The most common breakdown is voltage skeleton line forfeit, but other breakdowns like have pressed with the undervoltage must monitor. The wrong routine adopts the movement is decided by the application. The simple the movement is causes all skeleton lines to be at the electricity saving condition, but the programming function can cause you to carry on the comprehensive control. A decisive function is causes all voltage skeleton line to be at the electricity saving condition. An external signal (possibly comes from main processor) to be possible to inform MSP430 to cause the processor power source to be at the electricity saving condition. In this example, electricity saving sorting happen to with adds electricity sorting to be opposite, but you may define any sequence. One kind of movement which increases for the electricity saving sequence possibly meets the interchangeable uses and borrowed uses load, so that to can output the filter capacitor to carry on the electric discharge. The reason that this design uses the TPS725xx low pressure drop manostat, is because they may provide the fast transient response and the stability through any output capacitor. However, certain application possible need very big output capacitor to maintain the stability and the transient response. In this case, if can cause these filter capacitor to carry on the electric discharge to be possible to increase MTBF.
