•Can be able to bear or endure to suffer cold car to start and provide the power source of 3 stable output

•4 stable output (course of the 4th power source serves as SEPIC)

•Rely on the step up of power supply of manostat of a step-down controller

Can be able to bear or endure to suffer cold car to start and provide the power source of 3 stable output

 

In car application, the 5 V that needs to rely on stability, 3.3 V and the power source course under 2 V are various imitate and digital IC power supply, these IC may need course of different power source, use at I/O of content, processor and kernel. These power source course are to use 12V nominal VBAT (of car batteries voltage its come in 8 V normally inside the limits of 16 V) of generation. Efficient the need that step-down manostat can satisfy most circumstance, but during cold car is started VBAT can fall to last to 2 V a few millisecond, if direct from VBAT power supply, criterion right now pure support step-down manostat will lose stabilized voltage status.

 

LT8603 step up controller can be in low the job below the voltage to 2 V, make its suit manostat of the buy before using those who regard step-down manostat as power supply very much thereby. VBAT falls to when 8.5 V is the following, step up controller is outputted (OUT4) is adjusted to come 8 V. Manostat of step-down of two tall voltage can spend cold car to start a process peacefully, offer constant 5 V and 3.3 V output, if pursue,1 is shown. Once VBAT is started from cold car,restore to come 8 V above, step up controller just has the effect of break-through diode simply. Manostat of tall voltage step-down can handle the VBAT that is as high as 42 V. In the graph 1 in, manostat of low voltage step-down from OUT2 power supply, can start in cold car 1.2 V is offerred in the process.

 

Graph 1: Can be able to bear or endure to suffer cold car to start and provide the power source of 3 stable output. Manostat of the buy before 3 step-down manostat uses a step up (VOUT4) power supply, start in cold car of a VBAT thereby accurate stabilized voltage is offerred for 3 all output in the process (also show at the) in the graph.

 

4 stable output (course of the 4th power source serves as SEPIC)

 

VBAT can be in tall n for long, for example: Aid in double batteries push during starting or in 24V system. This pair of graphs 1 medium step up manostat does not have an influence, when 8 V of VBAT prep above, VBAT is passed, but the electric current of manostat of step-down of two tall voltage outputs ability to be heated up limitation below taller VBAT condition normally, because switch loss increases be caused by,this is, be in especially in car application below frequency of commonly used 2 MHz switch.

 

The working voltage that temperature rise can press manostat through reducing switch frequency or bring down to fall gives control. In the graph 2 in, the 4th passageway is installed to be SEPIC, control manostat power supply for tall voltage drop, the output of this passageway is adjusted to be in 12 V, this is the efficiency that suits step-down manostat most. Through running step-down manostat with optimal efficiency, can make temperature rise is in good controlled position. Graph 2 show the simple and easy method that went out to produce 4 accurate stabilized voltage one kind to output. Below light laden condition, this circuit can be being inputted low to stabilized voltage action holds when 2 V.

 

Graph 2: It is implementation only efficient and optimize and press manostat by the tall voltage drop of power supply of a SEPIC.

 

Rely on among them the step up of power supply of manostat of a step-down controller

 

The tall voltage that some of car application needs a stability (for instance 54 V) . A kind of method that produces course of this stable tall voltage is to use among them the output of manostat of step-down of a tall voltage comes manostat of drive step up, if pursue,3 are shown. Want the voltage of the smallest input of manostat of step-down of tall voltage of VBAT prep above only, so all 4 output are stability. Step-down manostat restricted the biggest electric current of step up converter, can protect step up converter to escape the damage that suffers short circuit consequently, offer chase periodic electric current to limit a function.

 

Graph 3: 4 stability of step up converter are outputted from the passageway power supply of 3 step-down manostat.

 

Use charge the additional and stable voltage that pump offers

 

If the graph is shown 4 times, can add to charge to SEPIC circuit pump circuit, in order to offer another stable output. If the stabilized voltage curve in the light of different input voltage pursues 4 are shown. Same, also can complement a negative output charges pump loses power source track with generation.

 

Graph 4: Charge pump circuit offerred extra tall voltage output.

 

EMI function

 

LT8603 used clock of a two-phase. Passageway 1 with the passageway 180° runs 2 different photograph, the peak value that reduced step-down manostat consequently inputs electric current, and conduce reduces EMI. The high density of electronic component needs to heat up function and EMI function carefully evenly. LT8603 demonstrates circuit DC2114A illustrate one is optimized to realize low EMI only, passed CISPR 25 5 kind the layout that peak value limitation asks. Graph 5 show the radiation EMI result that gave to use perpendicular polarization (come in 30 MHz the) inside limits of 1000 MHz frequency. The input is 14 V, load of a 1 A is had in every output.

 

Graph 5: LT8603 DC2114A CISPR 25 5 kind radiation EMI, 30 MHz comes 1 GHz.

 

Conclusion

 

LT8603 is passed 3 step-down manostat and a step up controller are compositive in cabinet 6 Mm X 6 Mm QFN in enclosing, offerred general with compact power source solution. Every step-down manostat has in-house mains switch, chase cycle to electric current is restricted and dog / function of the soft control that start. Develop of its synchronism commutate attacks can provide the efficiency that is as high as 94% . Sudden mode (Burst Mode®) operation is the static state electric current is maintained it is under 30 µA (all passageways all guide a) , suit to maintain the system that put through from beginning to end very much. 2 V makes to the wide input limits of 42 V and comprehensive function LT8603 suits the application with car and other slashing requirement very.