ADI has always been a high-end atmospheric company in my mind, especially in the analog-to-digital conversion, analog circuit part has an irreplaceable position, but the only drawback is that the price is too expensive, the ADE7878/ADE7880 has been used in the last year. Meter power calculation, weak signal acquisition of AD8221 instrumentation amplifier highway weighing system. In a recent project we used AD9852 to generate the sine wave signal we need for our testing equipment.
Our requirement is to generate a 0-2000V (peak-to-peak) sine wave AC signal within 20ms to detect the products we need to test. In this solution we use the following chips:
STM32F407 high-speed control chip is responsible for sampling the generated high-voltage voltage and controlling the signal generated by AD9852. The signal of AD9852 completes the sine wave of 50KHz from 0V to 3.3V within 20MS. After the op amp, it outputs 0-20V low-voltage power supply. The voltage is boosted by a 1:100 times transformer, and the AC voltage of 0-2000V is output. After the full bridge, the DC power is output. After the resistor is divided, the low voltage signal that can be sampled by the AD210AN high voltage isolation module is fed back to the STM32F407 to detect the data. The change in voltage.
First look at the advantages of these two ADI chips and modules:
The AD9852 system has a maximum clock of up to 300MHz, supports up to 120M, and the internal 48-bit programming frequency is even more powerful. It can achieve frequency accuracy of up to 0.01Hz. This accuracy is quite powerful, especially for frequency. It is not easy to get to 0.01Hz! Secondly, the internal 12-bit DA is sufficient for the use of this scheme. Of course, just said that it is to output 0-3.3V voltage within 20ms, then the amplitude adjustment function of this chip is very important, with 14bit programmable phase inside. The register and 12-bit amplitude tuning function make it easy to generate high-stability analog signals with programmable frequency, phase, and amplitude control.
AD210AN is a very powerful isolation chip. There are many manufacturers in China to copy this isolation module, mainly for high-voltage detection and measurement. Of course, it is mainly based on Jin Shengyang, but since it is ADI, it is quite People's place, otherwise it will not be the analog boss, the module supports 2500V work, the peak of 3500V works continuously, the nonlinearity also achieves plus or minus 0.012%, the internal input and output and power supply achieve complete isolation, 20K bandwidth The most important point is that the isolation voltage and non-linear characteristics of this module can help us to easily isolate the high voltage after isolation.
These two things are not cheap, AD9852 is okay, AD210AN in Taobao's price of up to 500 yuan, quite cheap! ! ! ! But even the best performance, or we burned a few, every time burning is money. . . The specific symptom is that the voltage does not change after the output is isolated.
In the whole scheme, the DDS part is good, but for the AD210AN part, it is a lot of damage, mainly reflected in an anti-surge performance, because our output 2000V voltage may be broken down to 0V at any time, this When the fire flashes, the scorpion is dead, and the devil and the ghost are infested. At this time, there will be a strong interference. The USB mouse and USB keyboard with no connection will be disturbed. The interference is transmitted through the wire on the back of the machine. STM32F407 was directly killed, and the system was not controlled. At this time, the transformer output a relatively high voltage, which caused the safe working range of the AD210AN to be burned. . . . We have been burned down more than 10 500, heartache. . . . .
Old burning AD9852 is good (AD9852 has never been damaged), the old burning AD210AN can not stand, the current solution is to use TVS protection on the input of AD210AN, add magnetic ring on all levels of cable, increase isolated power, increase shielding, etc. Various methods are solved. The modules at all levels use fully enclosed metal protective shells and improved grounding methods. After two months of continuous improvement, the current effect can guarantee the normal operation of the single-chip microcomputer during power supply jump, and has not encountered AD210AN for the time being. The situation of burning.
Attach a sentence:
Burned so many AD210AN your boss knows? Haha, I don't know. . .
Removed an AD210AN black ball is not an inductor