The ISOW7741-Q1 and
ISOW7742-Q1 devices have multiple protection features to create a robust
system level solution.
- The Enable DC-DC / FAULT protection feature
(EN/FLT) can be used as either an input pin, to enable or disable the integrated
DC-DC power converter, or as an output pin, which works as an alert signal if
the power converter is not operating properly. In the /FAULT use case, an alert
is reported if VDD > 7 V, VDD < 2.5 V, or if the
junction temperature >170°C. When a fault is detected, this pin will go low,
disabling the DC-DC converter to prevent any damage.
-
An over-voltage clamp feature
is present on VISOOUT which will clamp the voltage at 6 V, when
VSEL = VISOOUT, or 4 V, when VSEL = GND2, if there is an increase
in voltage seen on VISOOUT. It is recommended that the
VISOOUT stays lower than the over-clamp voltage for device
reliability.
-
Over-voltage lock out on VDD will occur when a voltage higher than
7 V is seen. The device will go into a low power state and the EN/FLT pin
will go low.
- The device is protected against
output overload and short circuit. Output voltage starts dropping when the power
converter is not able to deliver the current demanded during overload
conditions. For a VISOOUT short-circuit to ground, the duty cycle of
the converter is limited to help protect against any damage.
- The device is protected against
output overload and short circuit. Output voltage starts dropping when the power
converter is not able to deliver the current demanded during overload
conditions. For a VISOOUT short-circuit to ground, the duty cycle of
the converter is limited to help protect against any damage.
- The device is protected against
output overload and short circuit. Output voltage starts dropping when the power
converter is not able to deliver the current demanded during overload
conditions. For a VISOOUT short-circuit to ground, the duty cycle of
the converter is limited to help protect against any damage.
- Thermal protection is also
integrated to help prevent the device from getting damaged during overload and
short-circuit conditions on the isolated output. Under these conditions, the
device temperature starts to increase. When the temperature goes above 165°C,
thermal shutdown activates and the primary controller turns off which removes
the energy supplied to the VISOOUT load, which causes the device to
cool off. When the junction temperature goes below 150°C, the device starts to
function normally. If an overload or output short-circuit condition prevails,
this protection cycle is repeated. Care should be taken in the design to prevent
the device junction temperatures from reaching such high values.