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Low-side and high-side drivers with open-circuit and short-circuit detection |
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Written by Stephane
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jeudi, 21 février 2008 |
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According to Failure Mode Effects Analysis (FMEA), you may implement a circuitry in order to detect the failures on a digital output.
The following schematics allows to detect open-circuits and short-circuits on low-side and high-side drivers. The 'Control' and 'Status' wires are connected to a microcontroller.
Once the failure is detected, the microcontroller should disable the driver in order to avoid the transistor destruction or overheating.
Low-side detection
The transistor here has a digital command (like Philips BUK127). You may insert a resistor on the base for a classic NPN or N-FET transistor. You can download the BUK127 datasheet here (PDF, 67Kb)
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Control Pin
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Status Pin
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Detection
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0
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0
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Normal operation, output disabled |
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0
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1
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Short-circuit to ground or open-circuit |
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1
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1
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Normal operation, output enabled |
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1
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0
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Short-circuit to Vcc |
High-side detection
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Vcc
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R1
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R2
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5V
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0 ohms
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open
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11 - 14V
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10Kohms
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18Kohms
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23 - 28V
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10Kohms
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47Kohms
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R1 and R2 are choosen to have 4V < UR1 < 5V
The transistor here has a digital command (like Infineon BSP452). You may insert a resistor on the base for a classic PNP or P-FET transistor.
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Control Pin
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Status Pin
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Detection
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0
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0
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Short-circuit to Vcc
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0
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1
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Normal operation, output disabled
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1
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1
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Short-circuit to ground
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1
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0
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Normal operation, output enabled |
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Last Updated ( vendredi, 22 février 2008 )
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