The data communication link of rash club should come true below harsh industrial environment, RS-232 diagnostic port must be in RS-232 cable network and connect port of a segregation is offerred between all, increase systematic stability in order to prevent the voltage aiguille in loud noise environment and road of ground connection annulus (graph 1) technology of converter of compositive type DC/DC realizes the IsoPower® that the power source segregation of.RS-232 communication link uses power source of segregation type DC/DC or ADI firm.

 

The signal of RS-232 communication link keeps apart benefit consumed coupler or the ICoupler® technology of ADI company comes true.

 

Graph 1. Keep apart link of type RS-232 communication typically
 

Graph 2. Isolating function
 

If the graph is shown 2 times, segregation bar is between RS-232 bus line and every system that are linked together with this bus line offer report to keep apart, allow to transmit digital data in two already, can prevent electric current of road of ground connection annulus to had flowed again; The noise that can eliminate coupling to go up to telecommunication cable so, drop signal thereby lack fidelity with the error.

 

 

Want to offer communication interface of segregation type RS-232, the parts of an apparatus of two end must be kept apart each other with connects RS-232 cable. Want to keep apart data link, must be opposite data signal circuitry and use at drive the power source of this cable undertakes keeping apart. Come from on diagnostic port the data of UART needs to span to keep apart bar and transmit the RS-232 that goes up to side of segregation bus line to send and receive implement. Power source of this locality 5 V/3.3 V also needs to span the RS-232 that segregation bar will come to go up to keep apart bus line side is sent and receive implement power supply. Industrial PC end needs as much such: Data and power source all need to span segregation bar (graph 3) . Come through keeping apart parts of an apparatus and RS-232 cable network, diagnostic port and industrial PC circuit all are protected, do not suffer harsh environment to leave a possibility coupling changes to the twinkling on RS-232 cable influence. The way of ground connection annulus that because diagnose port and industrial PC to carry existence to differ to receive ground potential and may appear,segregation still can break. The appears possibly Gao Gongmo voltage on RS-232 bus line cannot span segregation bar, protect the user that keeps apart data thereby.

 

Graph 4 compared skill of two kinds of main segregation. ICoupler technology (graph 4(a) ) use compose of thick film engineering technology to build the miniature that can realize 2.5 KV to keep apart piece on transformer, offer signal segregation in RS-232 system thereby. Older but the opto-coupler solution that employs extensively (graph 4(b) ) use glow diode (LED) and photoelectricity diode. LED is used at be telegraphic date changeover light, photoelectricity detector is used at winding smooth transition to be telegraphic date. The low changeover efficiency of itself of changeover of light produced by electricity brings about power comsumption opposite taller; Of photoelectricity detector slow fast answer a limitation its speed; And ageing problem can restrict its service life.

 

Graph 3. Keep apart type RS-232 interface
 

Graph 4. Segregation technology is compared
 

Through using brilliant circle class craft is in directly piece on production transformer, ICoupler passageway can with inferior cost mutual and compositive and as compositive as other semiconductor function together.

 

ADM3252E is a such example namely, it is the RS-232 of segregation type double passageway in a compact parts of an apparatus is sent and receive implement. ICoupler segregation technology is in at least the following the limitation that 5 respects overcame place of old-style opto-coupler solution to cause: Compositive (because ICoupler supports two-way operation, because this can narrow,total size reduces systematic cost) , function taller, power comsumption is lower, use easily and reliability is higher.

 

Till recently, span segregation bar transmission power source needs to use alone DC/DC converter or custom-built schism method, former bulk is opposite bigger, price is high and segregation is inadequate, latter criterion volume is huge and design hard. Even if in keeping apart communication of type RS-232 data to wait to need the application of a few segregation power source only, these methods also are exclusive and feasible replacement scheme all the time.

 

To solve this one problem, ADI company research and development made a complete completely compositive type solution, use small transformer to span signal of segregation bar implementation and power source are transmitted. This is technology of perfect to us ICoupler is outspread, it is a kind of revolutionary replacement scheme, call IsoPower. Can realize the signal that is as high as 2.5 KV and power source segregation in individual parts of an apparatus, consequently need not bulk giant, price is high and the segregation power source that designs hard. It is OK and remarkable the circuit of interface of RS-232 of type of cut and typical segregation board time of area, design and segregation system totle drilling cost. Later development introduces two kinds applicable the typical RS-232 of this technology designs a condition.

 

Graph 5. Design of segregation type RS-232 is compared
 

 

Graph the solution undertook the 5 traditional solutions that will use discrete element and completely compositive type compare. Carry out interface of RS-232 of double passageway of complete segregation type (graph 5(a) ) traditional pattern is the data segregation that uses opto-coupler to provide RS-232 link. Every data circuitry (TIN1, TIN2, ROUT1, ROUT2) need an opto-coupler and an exterior bumper. Segregation power source introduces transformer drive IC comes drive schism transformer, mix with simple rectification circuit LDO (low-pressure poor manostat) purify segregation type 5 V or course of power supply of 3.3 V ISO VCC together. When carrying out, this design needs 8 IC and a certain number of passive component, need to take up huge circuit board area. In the odd chip solution that shows in graph 5(b) place, can use an IC (ADM3252E) , two go Ou capacitance and capacitance of 4 charge pump will be 4 all signal to implement form of a complete segregation (interface of RS-232 of 2.5kV) double passageway.

 

ADM3252E (graph 6) send and receive RS-232 of a standard implement be united in wedlock with ICoupler of a 4 passageways, use at offerring the signal segregation of RS-232 data signal. It returns compositive IsoPower technology, in order to offer piece inside power source segregation. Through keeping apart ICoupler and IsoPower technical photograph is united in wedlock and compositive RS-232 is sent and receive implement, ADM3252E can be in individual enclose (12 Mm×The interface of RS-232 of complete segregation type that sacrificial vessel carries to 2.5 KV Rms keeps apart function inside 12 Mm) , and need 6 exterior electric capacity only.

 

This odd chip solution can the design time that place of interface of RS-232 of type of remarkable and cut segregation needs is mixed circuit board area. Because the component amount on PCB decreases apparently, because this can be reduced,make cost and raise dependability. In addition, ADM3252E need not undertake any modification, can use at 5 V or 3.3 V application, the design that avoided schism to design place to must undertake is changed.

 

IsoPower technology can offer segregation of 2.5kV power source on the chip that the 44 BGA that cite a base enclose directly, the high component transformer that need not use in traditional solution consequently. In addition, ICoupler technology can provide signal (data) segregation, consequently need not passageway of opto-coupler of 4 cent vertical.

 

 

Because RS-232 cable wants to be joined with one’s own hands by the user and disconnect, because this RS-232 blasts off (Tx) and receive (Rx) cites a base (TxD1, TxD2, RxD1, RxD2) ESD (electrostatic discharge) protection is very significant, in order to ensure interface is stable and reliable. ADM3252E protects ability to accord with standard of IEC 1000-4-2 (801.2) in the ESD on RINx and TOUTx, specific following place show:

 

Contact discharge: ±8 KV

Air gap discharge: ±15 KV

 

Graph 6. RS-232 of ADM3252E segregation, double passageway is sent and receive implement

To make RS-232 is sent and receive implement can work below extremely abominable in industrial application work requirement, segregation technology (ICoupler and IsoPower) offer Gao Gongmo twinkling to change immunity to interference (> 25 KV/μs) , this immunity to interference is to point to can retentive when keeping rated job the biggest in all modular voltage (logic and the voltage that bus line carries) pressure place rate. Twinkling luffing is spent is in all modular voltage approachs modular range. In all modular voltage is pressed place rate apply to in all the ascendant edge of modular voltage and drop along. Any twinkling that this norms ensures harsh environment issues coupling to go up to RS-232 cable change cannot damage RS-232 is sent and receive implement or bring about transmission mistake data, make data link has extremely tall stability thereby.

 

 

Segregation is sent and receive implement the segregation that can offer 2.5 KV between the logic of parts of an apparatus and bus line end. This segregation rating ensures logistic end does not have electric current can cable of RS-232 of pass in and out. It still ensures won’t voltage or transient state coupling reach logistic end then to RS-232 cable. 2.5 KV keeps apart protection to still be meant, the tall voltage that can protect the user of logistic end not to suffer RS-232 cable to go up to appear possibly or twinkling change influence. The 2.5 KV of ADM3252E keeps apart rating to accepting the attestation of following orgnaization: Laboratory of American insurance business (UL) , Germany is electric engineer association (VDE) and Canadian standard association (CSA) .

 

* UL attestation

* 1 minute 2, 500 V Rms, accord with UL 1577

* VDE certificate of conformity

* IEC 60747-5-2 (VDE 0884, part 2)

Peak value of * VIORM = 560 V

* CSA component checks and accept announcement #5A

 

 

ADM3252E is type of a double passageway, high speed, total segregation (data and power source) RS-232 is sent and receive implement, suit to work below the environment with electric harsh condition very much, or insert often unplug the circumstance of RS-232 cable. It is compositive 4 independent ICoupler numbers keep apart a passageway (two blast off, two are received) with converter of DC/DC of class of an IsoPower chip, offer 2.5 KVrms segregation, 25 KV/μs twinkling changes immunity to interference and protection of ±15 KV ESD. It accords with TIA/EIA-232E standard, rate of highest communication data is 460 Kbps. Piece inside times pressure implement with inverter support only power source works.

 

ADM3252E uses 3.0 V to come power supply of 5.5 V only power source, the power comsumption when having load is 20 MA. It uses 12 Mm×The 44 CSP BGA citing a base of 12 Mm are enclosed, rated temperature limits comes for –40°C + 85 ℃ , 1000 quote that order a quantity are 8.49 dollars / piece.

 

 

Segregation is sent and receive implement the rated segregation performance that PCB layout achieves 2.5 KV in be designed actually to ensuring is crucial. Main consideration element is to carry GND and bus line to carry the distance climbing report between GND logically (edge housing most stone’s throw) with clearance (the shortest air is apart from) . The logistic interface of ADM3252E does not need exterior circuit. Input and output power supply bring a foot to need power source bypass (graph 7) . Be about to understand directory of concerned PCB distribution and radiate (the more information of EMI) control structure, the radiate that consults AN-0971 applies note “isoPower parts of an apparatus please controls proposal ” .

 

Graph 7. The printed circuit that ADM3252E recommends board layout
 

Graph 8. Only channel RS232 is sent and receive implement application (A) ADM3251E norms (B) traditional method (method of C) ICoupler + IsoPower

 

Only to needing only channel (1 Tx, 1 Rx) of interface of RS-232 of type of 5 V segregation send and receive implement application, ADM3251E offers a 20 sheet that make SOIC of crural wide system enclose chip solution. ADM3251E is sent and receive implement integrated ICoupler and IsoPower segregation technology, also be the first can offer the surface that data circuitry and power source both keep apart completely to stick outfit RS-232 to send and receive implement. It has 2.5 KV to keep apart rating, accord with industrial standard to keep apart a requirement (UL1577 and DIN VDE 0884-10) . The rash club sex that this can ensure the place in achieving environment of loud noise work asks, if industrial automation and control apply medium segregation,type RS-232 diagnoses data port. Compare with traditional IC photograph, the watch is stuck (SMT) is enclosed can make circuit board space decreases 45% , conduce to quicken workmanship and reduce a system to develop cost (graph 8) .

 

Epilogue

 

Current, the RS-232 interface link in industry and instrument appearance application requires measure small, function reliable, cost is low and segregation is good. Send and receive with standard RS-232 interface through keeping apart chip class transformer implement compositive, can pass RS-232 of type of odd chip, total segregation to send and receive implement (contain segregation power supply) will offer afore-mentioned advantages. Double passageway ADM3252E and only channel ADM3251E can shorten apparently design time, the application that gives these requirements Yan Ke offers the high-powered solution of a kind of compact, reliable, low cost.