UC3842 BASED DC-DC Converter

[nishu's]

Please take a look at attached schematic and tell me if its going to work or not, If not what corrections are required.

its basically a Boost converter with following specification
1. Input DC BUS IS : 5.8 - 9V
2. Output: 9V @ 3A

SIGNAL MEANING:
a> DC BUS: 5.8 - 9 V
b> 9V_SHUTDOWN: DISABLE SWITCHING OF UC3845
c> 9V_OUTPUT_OFF: DISCONNECTS -9V_SUPPY PORT FROM GND PORT
d> u9V_CUR_SENSE: OVER CURRENT AND SHORT CIRCUIT PROTECTION USING
MICRO-CONTROLLER.



every suggestion is welcomed

 

[BradtheRad]

Your inductor is 10mH. It is common to use a much smaller value, below 1mH.

Your Q5 icon appears upside-down.

Check orientation of Q6, whether it's right side up.

 

[nishu's]

Corrected: i changed inductor to 330uH and Q5 was indeed misplaced drain should be connected to inductor. I am not sure whats wrong with Q6 as it was placed to cutoff output when UC3842 is not switching disabling input voltage to reach output, so i cant point it out.

 

[ahsan_i_h]

The name "-9V_SUPPLY" is confusing. It seems that it is a -9V supply. Its name should be like "GND(9V)"

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R44(1K) is too low. Minimum Rt specified on the Rt/Ct graph (datasheet) is 3k.

 

[nishu's]

am not considering component values for now as am in process of pcb design, so any help regarding misplaced component or layout would be a great.

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thanks for correction, do you think anything else is misrouted.

 

[ahsan_i_h]

There should be a capacitor between pin 7 & 5 of the IC. (power supply bypass capacitor)