Low-side and high-side drivers with open-circuit and short-circuit detection
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)
|
Control Pin
|
Status Pin
|
Detection
|
|
0
|
0
|
Normal operation, output disabled |
|
0
|
1
|
Short-circuit to ground or open-circuit |
|
1
|
1
|
Normal operation, output enabled |
|
1
|
0
|
Short-circuit to Vcc |
R1 and R2 are choosen to have 4V < UR1 < 5V
|
Vcc
|
R1
|
R2
|
|
5V
|
0 ohms
|
open
|
|
11 - 14V
|
10Kohms
|
18Kohms
|
|
23 - 28V
|
10Kohms
|
47Kohms
|
High-side detection
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. You can download the BSP452 datasheet here (PDF, 83Kb)
|
Control Pin
|
Status Pin
|
Detection
|
|
0
|
0
|
Short-circuit to Vcc |
|
0
|
1
|
Normal operation, output disabled |
|
1
|
1
|
Short-circuit to ground |
|
1
|
0
|
Normal operation, output enabled |