FAN7093 FAIRCHILD [Fairchild Semiconductor], FAN7093 Datasheet - Page 9

• Manufacturer Part Number: FAN7093
• Manufacturer: FAIRCHILD [Fairchild Semiconductor]

FAN7093_F085
High Current PN Half Bridge
December 2011
Note 1: Not subject to production test
7.2 Protection Functions
The device provides integrated protection functions. These are designed to prevent IC destruction
under fault conditions described in the data sheet. Fault conditions are considered as “outside” normal
operating range. Protection functions are not to be used for continuous or repetitive operation, with the
exception of the current limitation. In a fault condition the FAN7093_F085 will apply the highest slew
rate possible independent of the connected slew rate resistor. Over voltage, over temperature and over
current are indicated by a fault current flag I
at the IS pin. The following describes the protection
IS(LIM)
functions are listed in order of their priority. Over voltage lock out overrides all other error modes.
7.2.1 Over voltage Lock Out
To assure a high immunity against over voltage conditions like load dump, the device turns off the
low-side MOSFET and turns on the high-side MOSFET when the supply voltage exceeds the over
voltage protection level V
. The control IC returns to normal operation 120us after the supply
OV(OFF)
voltage decreases below the over voltage lock out level V
. In H-bridge configuration, this
OV(ON)
behavior of the FAN7093_F085 will lead to freewheeling in high-side during over voltage. If the load
current exceeds 90A in over voltage lock out, the IC turns off the high side driver and latches this state.
7.2.2 Under voltage Shut Down
To avoid uncontrolled motion of for example a driven motor at low voltages, the control IC will turn
off all MOSFETS, when the supply voltage drops below the turn-off voltage V
. The control IC
UV(OFF)
returns to normal operation when the supply voltage rises above the turn-on voltage V
.
UV(ON)
7.2.3 Over temperature Protection
The FAN7093_F085 is protected against over temperature by an integrated temperature sensor in the
control IC. Over temperature is turning off both output stages. This state is latched until the device is
reset by a low signal with a minimum pulse length of t
at the
pin, assuming the control IC
reset
temperature decreased by at least the thermal hysteresis Repetitive use of the over temperature
protection impacts lifetime.
7.2.4 Current Limitation
The current is measured in both MOSFETS of the FAN7093_F085. As soon as the current is reaching
the limit I
, the low- or high-side MOSFET is deactivated and the other MOSFET activated for t
.
CL
CLS
During that time changes at the IN pin are ignored. However, the
pin can still be used to turn off
both MOSFETs. After time t
the MOSFETS return to their initial setting. The error signal at the IS
CLS
pin is reset after 2 * t
. Unintentional triggering of the current limit circuitry through short current
CLS
spikes (e.g. inflicted by EMI coming from the motor) is suppressed by an internal filter. Reaction delay
time of the filter circuitry is affecting the current limit level I
depending on slew rate of the load
CL
FAN7093_F085 Rev. C1
9
www.fairchildsemi.com