Ultra-Precise, Current-Sense Amplifier

 

 This ultra-precise current sense amplifier that can measure voltage drops across shunt resistor, R1 over a wide common mode range from 2.7 V to 120 V. 50Ohm resistor has been chosen so that 1A current will provide 1V at the output pin.

Driving a Bicolor LED from a Single Output Pin

 

This circuit demonstrates how to control bi-color LED from a single output pin using two PNP transistors. Java Script simulation link is as below.

                                   👉  https://tinyurl.com/22y3w9er                                  

Protecting Microcontroller Input TINA (TI) Simulation

Over Current Protection at Output Stage/ Pins

 

This circuit helps to limit the output current less than 20mA which can be sense and set by R1 & R8. It also disconnects I/O when the output shorts to positive high voltage or negative high voltage by limiting the current.

The diode, D1at the output and 5V0 pin is used to suppress the kick-back voltage from an inductive load that is excited when the drivers are turned off (stop sinking) and the stored energy in the coils causes a reverse current to flow into the coil supply through the kick-back diode

How to use MOSFET for Hide Side Switching

 

This circuit can be used for high voltage (100V max) and high current (33.6A) high side load switching. P-Ch MOSFET,Q1 has been chosen as it as very low ON-Resistance. For high voltage switching, R1 and R2 help to limit the VGS not to exceed VGS max. Another option is adding Zener diode across Gate and Source. N-CH MOSFET, ON/OFF control is driven by small signal N-CH MOSFET, Q2. When ON/OFF CTRL is low Q2 is OFF. When it is high, Q2 activate lowering P-CH gate voltage via R2 which also limits the current.

Overvoltage Protection

 

This circuit monitor VIN and protect the output voltage by a series connected transistor Q14. During over voltage condition Q14 B is turn on which cause Q14A to disconnect output to VIN. Desired overvoltage limit is set by D10 plus VBE of Q14. For example, if the required cutout voltage is 12V, Zener voltage of D10 has to be 12-0.6= 11.4 V.

 

Altium Designer : Schematics Transfer to PCB

 Import Changes from Schematics to PCB in Alitum as below.

1) Compile the Project

2) Design >> Import Changes From XXX.PrjPCB

3)Execute Changes

Zuken Cadstar : Schematics Transfer to PCB

 

Transferring schematics Design file to PCB in Zunken CADSTAR 16 as below. Electrical Rules Check, ERC can be done before transferring to PCB if you like.

Multiprotocol Transceivers

 Multiprotocol transceivers are very useful for those projects which require RS-232, RS-485, and RS-422 serial standards which reduce work load for software teams. 

There are many transceivers available in Markets and one of them is as shown below.

Product Link

Altium Designer : Working with an Image Object on a Schematic Sheet

 As a picture speaks a thousand words, adding an image object to the schematics is very handy for design review. Prefer method of adding PNG file as below.

CAN-BUS Termination and Protection

 A properly terminated CAN bus is terminated at each end with the characteristic impedance of the cable, this is typically 120Ω on each end for a 60Ω load on the CAN driver. The 60Ω–60Ω split termination is preferred to reduce high-frequency noise and common-mode drift. Usually, 60R resistor is not cost effective and a choice of 60.4R with 1% tolerance is better.

If we are using CAN-BUS for long distance for more than 50m, it is advised to reduce the bitrate to minimize an errors and signal distortions.

The maximum possible CAN Bitrate depends on the total CAN bus cable length: 

- 1 Mbit/s: max. 40 m

- 500 kBit/s: max. 100 m

- 125 kBit/s: max. 500 m  

To enhance CAN Bus reliability, communication BUS varistor can be added near next to the connectors.

If the device is intended to be used in harsh environment and required isolation due to ground potential difference between subsystems, Galvanic isolation barrier can be placed between CAN BUS transceiver and MCU. It is also important to use isolated DC-DC power supply for transceiver.