[introduction] LTC4217 heat is inserted unplug controller is opened with a kind of controlled means with the power source voltage that shuts circuit board, allow this to circuit board is inserted surely and pull out thereby electrified backboard. None strange, this is heat inserts the thing that unplugs controller place is done normally, but LTC4217 has a kind of character, make other heat inserts its excel unplug controller. It detects through mixing controller, MOSFET resistor is compositive in individual IC, simplified heat is inserted unplug systematic design.

LTC4217 heat is inserted unplug controller is opened with a kind of controlled means with the power source voltage that shuts circuit board, allow this to circuit board is inserted surely and pull out thereby electrified backboard. None strange, this is heat inserts the thing that unplugs controller place is done normally, but LTC4217 has a kind of character, make other heat inserts its excel unplug controller. It detects through mixing controller, MOSFET resistor is compositive in individual IC, simplified heat is inserted unplug systematic design. This saved many design time, need to cost otherwise choosing optimal controller / electric current of MOSFET combination, setting is restricted on the effect that value and careful design layout suffer excessive power comsumption with protecting MOSFET to avoid.

Compare with schism solution photograph, a of compositive solution distinct advantage is electric current limitative precision is well-known. In dividing vertical solution, the overall precision that electric current is restricted to be worth is the function that increases contributive component tolerance, and in LTC4217, it shows for individual 2A norms.

This are compositive the solution is returned through optimizing MOSFET is mixed detect resistor simplifies even fetch layout problem. Threshold value of limitation of surge electric current, electric current and overtime need not exterior component can be installed for acquiescent value, or use resistor and capacitor are adjusted easily, with getting used to all sorts of application better. This parts of an apparatus can enclothe 2.9V the wide voltage limits to 26.5V, include a temperature and voltaic monitor. MOSFET is passed use in a limited time fold return voltaic limitation and overheat protection to maintain in secure job area (SOA) .

LTC4217 can apply Yu Jiji to be configured originally conveniently, perhaps be installed through a few additional exterior component, in order to be used at having the application of special requirement.

Monitoring field effect is in charge of

LTC4217 has MOSFET electric current and temperature surveillance function. Voltaic monitor output and electric current of proportionate of MOSFET electric current, offer at the same time with voltage of MOSFET temperature proportionate. This allows to exterior circuit forecasts possible hitch and shut a system.

Medium electric current connects MOSFET to detect too resistor, detect the voltage changeover on resistor is electric current, current source gives I week stitch. The gain that begins from I is used at the MOSFET electric current of 1A on Monday for 50 μ A. Output electric current can use exterior resistor changeover to be voltage, with drive comparator or ADC. Compliant sex cites the tension of I on Monday the foot arrives from 0V (INTV copies to – 0.7V) .

MOSFET temperature presses linear and corresponding setting to cite a base with the report on I, temperature curve is shown 1 times like the graph. Below room temperature, the open circuit tension that should cite a foot to go up is 0.63V. In addition, when temperature of controller canal core exceeds 145 ° C, overheat closes circuit to close MOSFET, come when thermal drop guide again when 125 ° C.

Graph 1.V the relation of Aisaite and temperature

12V application

Graph 2 show the 4217V heat that gave to use acquiescent setting to insert unplug the LTC12-12 in application. The exterior component of exclusive need is the capacitor on INTV copies to needle. Control of electric current of voltaic limitation, surge and set of protective timer interiorly are the level that protects compositive MOSFET. Input voltage monitor is set beforehand for 12V power source, use the internal resistance voltage divider that comes from V DD power source is used at drive UV and OV to cite a base. UV condition happens in VDD to exceed 15.05V when the OVDD when V under 9.23V; .

Card of graph 2.12V, 1.5A is stationed in accept application

LTC4217 breaks the power source tension of circuit board with controlled means puts through and closing, allow this to circuit board inserts electrified backboard surely or pull out from electrified backboard thereby. Interiorly MOSFET guides before connecting, must satisfy a few requirements. It is VDD power source exceeds his above all 2.73V owes the INTV that presses a lock to decide n and interior to generate to copy deliver forked 2.65V. Next, UV and OV bring a foot to must indicate power input to be inside acceptable range. These requirements must be satisfied inside the duration of 100ms, already ended with ensuring any contact during inserting rebound.

Next, MOSFET guides through a controlled 0.3V/ms grid brae, if pursue,3 are shown. The voltage brae that outputs capacitor follows the slope of grid brae, it is setting of electric current of power source surge thereby:

Graph 3. Power source open

To reduce surge electric current further, add capacitor of a brae through arriving in grid between the ground (contain resistor of 0k series connection) , use more shallow than acquiescent 3.1V/ms voltage brae.

When power source of the DD when OUT is close to V, power supply is good indicator light (PG) turn into mobile condition. The definition with good power supply is FB brings the voltage on the foot to exceed 1.235V, and GATE brings a foot to be tall n. The surveillance of internal resistance voltage divider that FB brings a foot to cite a base through OUT outputs voltage. Once OUT voltage exceeds 10.5V door to be restricted, grid exceeds 4.2V to output voltage, PG brings a foot to stop to pull low, state power supply is good. Once OUT reachs VDD power supply, grid brae, till Qian the 6.15V that outputs in prep above.

LTC4217 has fold those who return a function is adjustable electric current is restricted to be worth, can provide protection in the light of short circuit or overload electric current. Acquiescent electric current is restricted to be worth for 2A, can adjust through a resistor is being placed between I setting of smaller electric current makes foot and ground connection. Switch power comsumption is too big during to prevent to be in electric current of have rendered great service is restricted, usable electric current can bring a foot to detect according to FB output voltage and reduce, if pursue,4 are shown.

Graph 4. Voltaic limitation threshold value is folded return

When the defer that exceeds timer setting when the time of joint of current limliting circuit, can have happened to shed breakdown. Bring timer the foot to bind copy to to international TV surely the 2ms that sets configuration of parts of an apparatus beforehand to use sheds overtime and 100ms cooling time too. After cooling 100ms, if shed breakdown to already kept clear of too, allow switch to guide again. Bring UV crural park 0.6V the following, increase next can keep clear of breakdown. FLT the join that cite a base brings a foot to be able to make proper motion of parts of an apparatus cleared to UV breakdown, guide again after cooling 100ms.

But process designing function

The LTC5 application that the graph shows 4217 times demonstrated adjustable and characteristic.

Card of graph 5.0.8A, 12V is stationed in accept application

Voltage divider setting owes UV and OV resistor to press and be pressed too involve threshold value, and FB voltage divider decides power supply is good jump change dot. GATE brings the R-C network on the foot to reduce grid brae from acquiescent 0.24V/ms to 0.3V/ms, in order to reduce surge electric current.

The 20k I installs resistor and in-house 20K resistor to form resistor voltage divider, with limitting electric current threshold value (fold before returning) the in part that reduces the original threshold value that limits to 1A electric current. Graph 6 medium chart show electric current restricts threshold value to install resistor for I each are not identical.

Graph 6. Current limliting is adjusted

Like the application in front, UV and FLT signal join are together, so that parts of an apparatus is closing bring up the rear to try automatically again,guide, shed breakdown in order to had been solved.

This exemple places resistor of a 20k to bring a foot to be used at the gain setting that outputs voltaic monitor to be 1V of every MOSFET electric current on Monday on I.

is not timer the join that cite a base copies to to INTV the 2ms that brings a foot to acquiesce to sheds overtime too, exterior capacitor of F of a 0.47 μ is used at setting 5.7ms overtime. During shedding incident too, exterior and time capacitor with 100 μ A on pull electric current to charge. If the voltage on capacitor achieves 1.2V door to be restricted, criterion MOSFET closes. The set formula that time capacitor is worth is as follows:

When MOSFET is in cooling condition, LTC4217 can discharge to time capacitor. When capacitance voltage achieves 0.2V, start in-house 100ms timer. Here after refrigeration period, breakdown is kept clear of (use when trying automatically again) , allow MOSFET to guide again.

Should lengthen breaker overtime to 2ms above when, the safe work area that considers MOSFET is very main. If the graph is shown 7 times,the SOA of the MOSFET that uses in LTC4217 pursues. When folding the voltage that returns electric current to be restricted to be worth and voltaic curve to reach maximum, can appear the worst power comsumption. It is 1A when electric current and when voltage is the half of 12V or 6V, can produce this kind of situation (refer to a graph 4, the FB when 0.7V cites a base) . Below this kind of circumstance, power is 6W, this decided to be 100ms the most for long (graph 7, when 6V and 1A) .

Graph 7. Field effect is in charge of curve of odd ionic and alkalescent wave motion

Conclusion

The main effect of LTC4217 is control heat is inserted and provide electronic breaker function. In addition, this parts of an apparatus still includes the protection to MOSFET, the key is SOA adds up to compasses sex, heat protection and limitation of accurate 2A electric current. Because have adjustable surge electric current, shed breakdown timer and voltaic limitation threshold value too, it still applies to all sorts of application. Tall compositive degree make LTC4217 is used easily, and use is extensive.

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