ATA6026 ATMEL Corporation, ATA6026 Datasheet - Page 15

• Manufacturer Part Number: ATA6026
• Description: H-bridge Motor Driver
• Manufacturer: ATMEL Corporation

3.8.2
3.8.3
3.8.4
3.9
4865C–AUTO–01/06
Behavior of the Bridge Drivers in Case of RESET
Undervoltage
Temperature Supervisor
Short Circuit Detection
This block switches off the external power MOS transistors in case of undervoltage on the
battery.
Function: In case of undervoltage alarm (V
off and the event will be signalled by switching ON the pin DG1 (see
the undervoltage condition disappears, after the next LOW to HIGH transition at pin PWM the
drivers for the external power MOS transistors will switch back to the status defined by the con-
trol pin DIR, and the pin DG1 will be cleared to LOW if there is no other event be signalled. The
SCI drivers are not influenced by the voltage supervisor. The comparator includes a hysteresis.
There is a temperature sensor integrated on-chip to prevent overheating of the ATA6026 and to
protect external NMOSFETS from a failure in external circuitry. In case of detected overtemper-
ature (150°C to 180°C), all drivers including SCI drivers will be switched OFF immediately and
both of the diagnostic pins DG1 and DG2 will be switched to HIGH to signal this event to the
processor.
The status thermal shutdown (TS) will be stored in a latch: After the next LOW to HIGH transition
at pin PWM, the drivers for the external power MOS transistors will switch back to the status
defined by the control pin DIR, the pins DG1 and DG2 will be cleared to LOW if there is no other
event to be signalled, and the SCI drivers immediately will switch to the status defined by the
control pin TX.
A hysteresis is built in to prevent fast oscillations.
Attention: With DG1 = DG2 = HIGH, short circuit is signalled as well as overtemperature.
To detect a short in H-bridge circuitry, internal comparators detect the voltage difference
between source and drain of the external power NMOS. If transistors are switched ON and the
source drain voltage difference is higher than the value VSC (4V with tolerances) for a time
greater than t
be switched off immediately, and the pins DG1 and DG2 will be switched to HIGH to signal this
event to the processor.
With the next programmed LOW to HIGH transition on pin PWM, the bits will be cleared and the
corresponding drivers will switch back to the status defined by the control pin DIR; the pins DG1
and DG2 will switch back to LOW if the short circuit condition has cleared.
In case of RESET (/RESET = LOW), the high-side drivers will be switched OFF and the low-side
drivers will remain in the status defined by PWM and DIR.
In case of overvoltage (OV), undervoltage (UV), thermal shutdown (TS), or short circuit (SC), all
the drivers will be switched off, independent of the status of the /RESET pin.
SC
, the signal SC (short circuit) will be set, the external power MOS transistors will
THuV
), the external NMOS transistors will be switched
Table 3-3 on page
ATA6026
14). If
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