Surge Pulse Clamping with Ceramic Capacitors

Started by Klaus Kragelund in sci.electronics.design9 years ago 40 replies

Hi For an application I need to protect the electronics of an RS485 interface from surges (8/20us 1kV pulse) The normal way be to use a...

Hi For an application I need to protect the electronics of an RS485 interface from surges (8/20us 1kV pulse) The normal way be to use a transzorb, in a SMA housing or even a SOT23 device. That is not possible since we have to be able to withstand up to 30V DC on the bus also (that is handled by a special RS485 IC) The problem is that the selected breakdown voltage of the transzorb ...


Discrete custom design of RS485 driver

Started by Klaus Kragelund in sci.electronics.design9 years ago 111 replies

Hi The standard RS485 drivers available has a minimum voltage of 3V and a rarther large drop voltage when loaded with the defined bus load for...

Hi The standard RS485 drivers available has a minimum voltage of 3V and a rarther large drop voltage when loaded with the defined bus load for Modbus of 54ohms, and this causes problems for our design since we have limited power available for driving the bus So, we are thinking about designing our own driver in discrete components, so we can reduce the supply down to 2V and still comply with...


rs485 and RTN

Started by ice in sci.electronics.design11 years ago 21 replies

hi all system: 9600bps rs485 half-duplex with single master and multiple slaves; both master and slave connector have 3 pins (A,B,RTN) cable:...

hi all system: 9600bps rs485 half-duplex with single master and multiple slaves; both master and slave connector have 3 pins (A,B,RTN) cable: about 500mt shielded cable with 2 twisted pairs inside, one pair used for A/B signals other pair used for RTN the system works well questions: 1. the shield of the cable is connected to earth ground (yellow-green wire) at master side only: is t...


Lighning protection

Started by Phil Hobbs in sci.electronics.design7 years ago 35 replies

So I'm looking at lightning protection for the mezzanine units of the cotton spark detection system. I have a copy of Standtler's book,...

So I'm looking at lightning protection for the mezzanine units of the cotton spark detection system. I have a copy of Standtler's book, "Protection of electronic circuits from overvoltage", which is useful but a bit out of date (1989). (He doesn't know about HV depletion MOSFETs or polyfuses, for instance.) It looks as though I can protect the isolated RS485 pair and the power/commo...


complementary cmos levels

Started by Anonymous in sci.electronics.design3 years ago 11 replies

I have a fast 3.3 volt logic level that I'd like to split into inverted and non-inverted copies with minimum time skew. I think that TI...

I have a fast 3.3 volt logic level that I'd like to split into inverted and non-inverted copies with minimum time skew. I think that TI once had a buffer with one input and complementary outputs, but I can't find a reference to that. It's probably slow and obsolete. A TTL to RS485 converter sort of works but would be slow. I could use two separate XOR gates, one as a buffer and the...