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Calculated Component Values for eFuse Protection Functions
Overcurrent Limit Resistor
According to the datasheet, the formula for determining the resistance of a particular current limit is…
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Overcurrent Blanking Interval Capacitor
The overcurrent blanking interval is the period where a current past the limit threshold is ignored for a time period. This is used to help deal with transients and avoid false alarms.
The overcurrent blanking interval is defined as…
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$t_{ITIMER} (ms) = \frac{C_{ITIMER} (nF) * \Delta V_{ITIMER} (V)}{I_{ITIMER} (\mu A)}$ |
Where the capacitance for a specific blanking interval is…
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$t_{ITIMER} (ms) = \frac{C_{ITIMER} (nF) * \Delta V_{ITIMER} (V)}{I_{ITIMER} (\mu A)}$ |
Current Monitoring Resistor
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$ V_{IN}(OV) = \frac{V_{OV}(R)*(R1+R2)}{R2}$ |
The eFuse turns OFF the power to the output when the voltage at the OVLO pin is greater than the OVLO rising threshold, VOV(R). The output power is turned ON again after the voltage at the OVLO pin falls below the OVLO falling threshold, VOV(F).
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Another potential option could be the AD8400. It has a smaller package, more resistance positions, and a smaller package, but is significantly more expensive.
External FET: SQJ868EP-T1_GE3 (
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The TP25983 offers the ability to drive the gate of an external FET to block reverse current.
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