ATA5279 ATMEL Corporation, ATA5279 Datasheet - Page 10

• Manufacturer Part Number: ATA5279
• Manufacturer: ATMEL Corporation

10
ATA5279 [Preliminary]
As described in the principle schematic of a driver stage above, a test structure consists of two
switchable current sources (one to VDS and one to GND) and a comparator that converts the
voltage level on the line into a digital signal. The switches for the current sources can only be
controlled in diagnosis mode, with the corresponding coil being selected (see also Driver Com-
mand description). Note that one switch is always closed, either the high-side or the low-side
switch of one test structure. These structures are independent, i.e., they can be set up for each
line individually and at the same time.
The status of the connection lines of the selected coil can be read out with a SPI command.
In the following example, there is a short circuit between the positive coil connections of coil 1
and 2.
Figure 3-5.
Taking the circuit situation shown above, the test run starts with both S_L1P and S_L2P
switches closed (default state when entering the diagnosis mode for the first time). The
read-back of the line state result in both times 0, which is not unexpected. However, the result
does not change when either altering the channel 1 or the channel 2 switch setting. That can be
caused both by the failure shown above and by short-circuits of both lines to ground. The final
diagnosis can be identified by changing both channels to the high-side switches (S_H1P and
S_H2P). In this case, the two status lines both return 1s – which eliminates the possibility of two
short-circuits to ground.
Example 1, Using the Diagnosis Mode
S_H1P
S_L1P
Status_1
A1P
R
GND
VDS
Short
A2P
Status_2
S_H2P
S_L2P
9125A–RKE–04/08