BTN7963B Datasheet, PDF (15/26 Pages) Infineon Technologies AG – High Current PN Half Bridge NovalithIC

High Current PN Half Bridge
BTN7963B
Block Description and Characteristics
5.3
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 (Chapter 5.3.4). In case of overtemperature the BTN7963B will apply the slew rate determined by the
connected slew rate resistor. In all other fault conditions the highest slew rate possible will be applied independent
of the connected slew rate resistor. Overvoltage, overtemperature and overcurrent are indicated by a fault current
I_IS(LIM) at the IS pin as described in the paragraph “Status Flag Diagnosis With Current Sense Capability” on
Page 19 and Figure 12.
In the following the protection functions are listed in order of their priority.
5.3.1 Overvoltage mode (Smart Clamping)
If the supply voltage is exceeding the over voltage level V_OVM(ON) the device enters the overvoltage mode. The IC
operates in normal mode again with a hysteresis V_OVM(HY) if the supply voltage decreases below the Overvoltage
Mode OFF voltage level V_OVM(off). In case of overvoltage the device shuts the lowside MOSFET off and a fault
current I_IS(LIM) is provided at the IS pin. The highside MOSFET is still operational and follows the inputs IN and INH.
Current Limitation and Overtemperature Protection are still active for the highside switch, and can independently
switch off the highside MOSFET, if it was on before.
If the highside MOSFET is off, an implemented voltage clamp mechanism keeps the voltage drop -V_DS(HS) over
the highside at a certain level -V_{DS(HS)_CL}.
5.3.2 Undervoltage Shut Down
To avoid uncontrolled motion of the driven motor at low voltages the device shuts off (output is tri-state), if the
supply voltage drops below the switch-off voltage V_UV(OFF). The IC becomes active again with a hysteresis V_UV(HY)
if the supply voltage rises above the switch-on voltage V_UV(ON).
Note: With decreasing V_s < V_UV(OFF)max, activation of the Current Limitation mode may occur before Undervoltage
Shut Down with ambient temperatures less than 25°C. See Table “Switch-OFF Voltage” on Page 18.
5.3.3 Overtemperature Protection
The BTN7963B is protected against overtemperature by an integrated temperature sensor. Overtemperature
leads to a shut down of both output stages. This state is latched until the device is reset by a low signal with a
minimum length of t_reset at the INH pin, provided that its temperature has decreased at least the thermal hysteresis
ΔT in the meantime.
Repetitive use of the overtemperature protection impacts lifetime.
5.3.4 Current Limitation
The current in the bridge is measured in both switches. As soon as the current in forward direction in one switch
(high side or low side) is reaching the limit I_CLx, this switch is deactivated and the other switch is activated for t_CLS.
During that time all changes at the IN pin are ignored. However, the INH pin can still be used to switch both
MOSFETs off. After t_CLS the switches return to their initial setting. The error signal at the IS pin is reset after 2 * t_CLS.
Unintentional triggering of the current limitation by short current spikes (e.g. inflicted by EMI coming from the
motor) is suppressed by internal filter circuitry. Due to thresholds and reaction delay times of the filter circuitry the
effective current limitation level I_CLx depends on the slew rate of the load current dI/dt as shown in Figure 10.
Data Sheet
15
Rev. 1.0, 2009-09-09