BTS3256D Datasheet, PDF (20/30 Pages) Infineon Technologies AG – 10 mΩ smart power single channel low side switch with restart and variable slew rate

Smart Low Side Power Switch
HITFET - BTS 3256D
Control and Diagnosis
7
Control and Diagnosis
The BTS3256D provides digital fault feedback on the IN pin without the need of an ADC.
Additonally the device features an adjustable slew rate via the SRP pin.
7.1
Readout of Fault Information
The BTS 3256D provides digital status information via an increased current on the IN / Fault pin.
The voltage on this pin is pulled down to logic low when a fitting serial resistor is used. An example for the required
circuitry is shown in Figure 14. The increased current I_IN(fault) is one order of magnitude above the normal operation
current I_IN.
A 3k3 for a 3.3V µC or 5k6 for a 5V µC is recommended.
For detailed calculation please refer to “Dimensioning of serial Resistor at IN pin” on Page 26.
.
V
bb
V
CC
V
CC
Micro
controller
DO ^IDO
R1
=1 0
Fault 0
0
DI
GND
V_DI
V
S
BTS3256
I_IN
IN/Fault
GND
GND
Figure 14 Readout of feedback information and XOR logic in micro
Fault_readout.emf
7.2
Adjustable Slew Rate
In order to optimize electromagnitic emission, the switching speed of the MOSFET can be adjusted by connecting
an external resistor between SRP pin and GND. This allows for balancing between electromagnetic emissions and
power dissipation. R_SRP-min represents the minimum slew rate Slew rate_min and R_SRP-max represents the maximum
slew rate Slew rate_max.
A short to GND causes the minimum slew rate Slew rate_min.
Open pin condition causes the maximum Slew rate Slew rate_max.
Figure 15 shows the relation between the resistor value and the slew rate of BTS 3256D.
Datasheet
20
Rev. 1.0, 2009-05-05