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25 lines
931 B
Plaintext
25 lines
931 B
Plaintext
OPD Circuit breaker design notes
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Part Maxim - MAX892L
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This information is all from the data sheet.
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1. IC needs an active low on EN pin 3 to turn on.
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2. Limiting current is set by R_SET on pin 5 to ground. The resistor value is chosen
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according to the following equations.
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I_SET = I_LIMIT / I_RATIO
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R_SET = 1.240 / I_SET
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I_RATIO = 965 [p6]
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As designed I_SET = 50mA so R_SET = 23932.
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3. The net OPD_I_SET provides the voltage developed by a replica of I_OUT through R_set
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to ground. This current is I_OUT / 965. The output current can then be monitored by
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the MCU on this net.
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4. The fault pin 6 is an open drain active low and is pulled to ground when the IC starts
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current limiting or when the IC temperature exceeds 135C.
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5. This part is an auto retry. If the IC exceeds 135C it turns off and then turns back on
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after the junction temp drops 10C. This can result in a pulsed output if the fault is
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not corrected.
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