MC33199 Datasheet, PDF (12/18 Pages) Freescale Semiconductor, Inc – Automotive ISO 9141 Serial Link Driver

FUNCTIONAL DESCRIPTION
INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
The MC33199 is a serial interface circuit used in diagnostic applications. It is the interface between the microcontroller and
the special K and L lines of the ISO diagnostic port. The MC33199 has been designed to meet the «Diagnosis System ISO9141»
specification.
This product description will detail the functionality of the device (see Figure 2, 33199 Simplified Internal Block Diagram). First,
the power supply and reference voltage generator will be discussed, then the paths functions between MCU, K and L lines will
be detailed. A dedicated paragraph will tell about the special functionality of the I1 pin, which allow high Baud rates transmission.
FUNCTIONAL PIN DESCRIPTION
VCC (VCC)
5V typical power supply pin. Typical supply current is less
than 1.5mA.
REF-IN-L (REF-IN-L)
Input reference for C2 comparator. This input can be
connected directly to REF-OUT, with or without a resistor
network, or to an external reference.
REF-IN-K (REF-IN-K)
Input reference for C1 comparator. This input can be
connected directly to REF-OUT, with or without a resistor
network, or to an external reference.
LO (LO)
Output of C2 comparator, normally connected to a micro-
controller I/O. If L input > (REF-IN-L + Hyst/2) then output LO
is in high state. If L< (REF-IN-L - Hyst/2) then output LO is in
low state, output transistor ON.
This pin is an open collector structure. A Pull up resistor
should be added to VCC.
Drive capability of this output is 5mA.
RXD (RXD)
Receive output, normally connected to a microcontroller I/
O.
If DIA input > (REF-IN-L + Hyst/2) then output LO is in high
state.
If DIA < (REF-IN-L - Hyst/2) then output LO is in low state,
output transistor ON. This pin has an internal pull up resistor
to VCC (2Kohm typ). Drive capability of this output is 5mA
TXD (TXD)
Transmission input, is normally connected to a
microcontroller I/O.This pin controls DIA output. If Txd is high,
the output DIA transistor is OFF. If Txd is low the DIA output
transistor is ON.
DIA (DIA)
Input / Output Diagnosis Bus line pin. This pin is an open
collector structure, protected against over current and short
circuit to VBAT (VS). When turning ON (TXD low), this pin will
pull the Bus line to Gnd, the current into DIA will be internally
limited to 60mA typ.
The internal power transistor has a thermal shutdown
circuit, which forces the DIA output OFF in case of over
temperature.
DIA is also the C1 comparator input. It is protected against
both positive and negative over voltage by a 38V zener diode.
This pin exhibits a constant input current of 7.5?A.
GND (GND)
Gnd reference for the entire device.
I1 (I1)
Bus source current pin. It is normally tied to DIA pin and to
the Bus line.
At static HIGH or LOW level Txd, the current source I1
delivers a current of 3mA (typ). Only during LOW to HIGH
transition, does this current increase to a higher value in
order to charge the key line capacitor (Cl<4nF) in a short time
(see fig 3 and 4).
L (L)
Input for C2 comparator. This pin is protected against both
positive and negative over voltage by a 38V zener diode.
This L line is a second independent input. It can be used
for wake up sequence in ISO diagnosis or as an additional
input bus line.
This pin exhibits a constant input current of 7.5µΑ.
VS (VS)
12V typical, or Vbat supply pin for the device. This pin is
protected against over voltage transients.
REF-OUT (REF-OUT)
Internal reference voltage generator output pin. Its value
depends on Vs (Vbat) values. This output can be directly
connected to REF-IN L and REF-IN-K, or through a resistor
network. Maximum current capability is 50µΑ.
33199
12
Analog Integrated Circuit Device Data
Freescale Semiconductor