ADI's precision LDO helps complete board design

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ADI's precision LDO helps complete board design [Copy link]

 

A long time ago, I did a project

I use the domestic alternative chip of STM32F405RGT6 as the main control to make an industrial control board. LDO needs to power the main control microcontroller, CAN transceiver circuit, storage circuit, SPI and other peripheral devices.

However, since the 64-pin MCU does not have an external VREF pin, and we know that this domestic chip will work unstably if VDD and VDDA are connected separately, so VDD and VDDA are connected together.

However, when the previous stage changes, VDDA is used as the reference source for ADC sampling. VDDA should originally be connected to a single power supply. The ADC sampling needs to be as accurate as possible, so the LDO power supply requirements are very high. Therefore, a wide input voltage and low noise LDO is selected. The schematic diagram is as follows

Because the power supply range of my front-stage circuit is relatively wide and subject to fluctuations, I hope that the power supply of my rear-stage circuit will be as stable as possible.

Look at the parameters of ADI LT1763

Wide input voltage: 1.8V-20V. Nowadays, there are relatively many ICs with wide input voltage.

The output current is 500mA, but the noise is really low.

Compare with the common LM1117

Performed software simulation of LDO

Download LTSPICE official simulation software and create a new circuit diagram

Select the LDO model you want to simulate

Simulate according to the schematic diagram in the manual

Setting the Input Voltage

My input voltage is around 4-15V, and the simulation results are OK

火辣西米秀

There are also LTSPICE simulation results, learned