TLE7184F_15 Datasheet, PDF (21/38 Pages) Infineon Technologies AG – System IC for B6 motor drives

TLE7184F
Interface, VDH Switch and INH Digital Output
8
Interface, VDH Switch and INH Digital Output
8.1
PWM Interface (IFMA)
The TLE7184F has an integrated interface supporting the typical PWM interface between a remote master ECU
and the µC. The link to the external master ECU is a single wire communication based on the battery voltage and
running typ. with about 10 to 400 Hz. The information is encoded in the duty cycle of the signal.
This communication line requires a signal conditioning to connect to the on board µC.
The integrated circuit supports the incoming data path.
The outgoing data path is formed by external components
uC
VCC
IFuC
Interface_uC
TLE 7184 F
VDD
VS
VS
Wake up
340k
IFMA
interface
KL 30
Pull up
T1
GND
700k
R1
10k
T2
ECU
T3
Figure 9 Structure PWM Interface
The integrated circuitry is described in Figure 9.
The main task of this interface is level shifting and protection of the µC.
The IFuC signal is following the IFMA signal, passing the duty cycle information from IFMA to the IFuC.
The µC port is used as input and is listening to the IFuC signal. The voltage at IFMA is monitored. If IFMA is low
the IFuC open drain output is switched on - forcing the IFuC signal to low.
If IFMA is high, the IFuC open drain output is deactivated and the IFuC signal is pulled to high by the internal pull-
up resistor.
The IFMA input is used as well for wake-up. See Chapter 9.1
Influence of serial resistor at IFMA pin
As shown in Figure 9 a 10k resistor R1 is recommended to protect the IFMA pin against negative voltage levels
coming from the interface signal. The integrated pull down and pull up resistors at the IFMA pin form a voltage
divider together with the resistor R1. This will influence the resulting switching level of the IFMA interface in the
application compared to the levels specified directly at the IFMA pin.
In this datasheet an additional parameter is provided to calculate the influence of the 10k resistor. The specified
IFMA input current divided by Vs allows to calculate the drop over R1 with the following formula:
Data Sheet
Voltage
_
drop
_
over
_
R1 =
I _IFMA
V_VS
*V_VS
* R1
21
Rev. 1.1, 2011-04-08