BTN7963B Datasheet, PDF (19/26 Pages) Infineon Technologies AG – High Current PN Half Bridge NovalithIC

High Current PN Half Bridge
BTN7963B
Block Description and Characteristics
5.4
Control and Diagnostics
5.4.1 Input Circuit
The control inputs IN and INH consist of TTL/CMOS compatible schmitt triggers with hysteresis which control the
integrated gate drivers for the MOSFETs. Setting the INH pin to high enables the device. In this condition one of
the two power switches is switched on depending on the status of the IN pin. To deactivate both switches, the INH
pin has to be set to low. No external driver is needed. The BTN7963B can be interfaced directly to a
microcontroller, as long as the maximum ratings in Chapter 4.1 are not exceeded.
5.4.2 Dead Time Generation
In bridge applications it has to be assured that the highside and lowside MOSFET are not conducting at the same
time, connecting directly the battery voltage to GND. This is assured by a circuit in the driver IC, generating a so
called dead time between switching off one MOSFET and switching on the other. The dead time generated in the
driver IC is automatically adjusted to the selected slew rate.
5.4.3 Adjustable Slew Rate
In order to optimize electromagnetic emission, the switching speed of the MOSFETs is adjustable by an external
resistor. The slew rate pin SR allows the user to optimize the balance between emission and power dissipation
within his own application by connecting an external resistor R_SR to GND.
5.4.4 Status Flag Diagnosis With Current Sense Capability
The status pin IS is used as a combined current sense and error flag output. In normal operation (current sense
mode), a current source is connected to the status pin, which delivers a current proportional to the forward load
current flowing through the active high side switch. If the high side switch is inactive or the current is flowing in the
reverse direction no current will be driven except for a marginal leakage current I_IS(LK). The external resistor R_IS
determines the voltage per output current. E.g. with the nominal value of 8.5k for the current sense ratio
k_ILIS = I_L / I_IS, a resistor value of R_IS = 1 kΩ leads to V_IS = (I_L / 8.5 A)V. In case of a fault condition the status output
is connected to a current source which is independent of the load current and provides I_IS(lim). The maximum
voltage at the IS pin is determined by the choice of the external resistor and the supply voltage. In case of current
limitation the I_IS(lim) is activated for 2 * t_CLS.
Normal operation:
current sense mode
VS
I_IS~ I_Load
I_IS(lim)
ESD-ZD
IS
Sense
output
logic
R_IS ^VIS
Fault condition:
error flag mode
VS
I_IS~ I_Load
I_IS(lim)
ESD-ZD
IS
Sense
output
logic
R _IS ^VIS
Figure 12 Sense Current and Fault Current
Data Sheet
19
Rev. 1.0, 2009-09-09