BTM7745G Datasheet, PDF (14/24 Pages) Infineon Technologies AG – High Current H-Bridge Trilith IC 3G

High Current H-Bridge
BTM7745G
Block Description and Characteristics
6.3.2 Undervoltage Shut Down
To avoid uncontrolled motion of the driven motor at low voltages the device shuts off (both outputs are tri-state),
if the supply voltage V_S drops below the switch-off voltage V_UV(OFF). In this case all latches will be reset. The IC
becomes active again with a hysteresis V_UV(HY) if the supply voltage rises above the switch-on voltage V_UV(ON).
6.3.3 Overtemperature Protection
The BTM7745G is protected against overtemperature by integrated temperature sensors. Each half bridge, which
consists of one high side and one low side switch, is protected by one temperature sensor located in the high side
switch. Both temperature sensors function independently. A detection of overtemperature through temperature
sensor leads to a shut down of both switches in the half bridge. This state is latched until the device is reset by a
low signal with a minimum length of t_reset simultaneously at the INH pin and both IN pins, provided that its
temperature has decreased at least the thermal hysteresis ΔT in the meantime.
Overtemperature protection is available up to supply voltage V_S = 18V.
For sufficient over temperature protection please consider also operation below the limitations outlined in Figure
4 and Figure 5.
Repetitive use of the overtemperature protection might reduce lifetime.
6.3.4 Current Limitation
The current in the bridge is measured in all four switches. As soon as the current in forward direction in one switch
is reaching the limit I_CLx, this switch is deactivated for t_CLS. In case of INH = 5V (high) the other switch of the same
half bridge is activated for the same time (t_CLS). During that time all changes at the related IN pin are ignored.
However, the INH pin can still be used to switch all MOSFETs off. After t_CLS the switches return to their initial
setting. The error signal at the ST pin is reset after 1.5 * t_CLS if no overcurrent state is detected in the meantime.
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 11.
I_L
I_{C L x}
I _CLx0
t _CLS
1 . 5 *t_CLS
O
t
V_ST
5V
O
t
Figure 10 Timing Diagram Current Limitation and Status Flag
Data Sheet
14
Rev. 1.0, 2010-05-28