TLE7186F

Interface, VDH Switch and INH Digital Output

Data Sheet

21

Rev. 1.2, 2016-01-28

8

Interface, VDH Switch and INH Digital Output

8.1

PWM Interface (IFMA)

The TLE7186F 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

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:

uC

Interface_uC

GND

TLE 7184 F

KL 30

Pull up

interface

ECU

T3

T1

VDD

VCC

IFuC

IFMA

T2

Wake up

R1

10k

VS

VS

700k

340k

1

*

*

1

_

_

_

R

V

V

I

R

over

drop

Voltage

VS

VS

IFMA

=