ATA5275 ATMEL Corporation, ATA5275 Datasheet - Page 8

• Manufacturer Part Number: ATA5275
• Description: Integrated 1.5 A peak current BCDMOS antenna driver IC dedicated as a 125 kHz wake-up channel transmitter for TPM applications
• Manufacturer: ATMEL Corporation

Diagnosis and Protection
Circuit Protection Cases
Error Diagnosis
8
ATA5275 [Preliminary]
This feature allows the user to operate the IC in a wide field of operational voltage field
and protects the driver stage and the antenna from antenna overcurrent.
The driver out square wave starts with a duty cycle of 50%. After tree or four cycles the
duty cycle can reach its maximum. As far as the peak current will stay smaller than
IA
rent the envelope of the peak current will be greater than IA
function will suppress the next driver output pulse to minimize the antenna current
overshoot.
The IC supervises several parameters of IC operation for transmission diagnosis and
circuit protection.
In any case of circuit protection mode or error detection the IC indicates this states
according to the transmission protocol via the DIO line (see chapter “Transmission
Acknowledge and Error Signal” on page 6).
The circuit protection is activated in normal mode. It is switched off in standby mode. In
case a protection switch-off occurs the half-bridge is set in tri-state mode.
For all cases, there is a filter implemented to debounce half-bridge switch-off for a time
of T
vated. Otherwise it is RESET.
These are the following circuit protection cases:
1. Load dump protection: In case the voltage at DVCC exceeds a voltage VBAT
2. Overcurrent protection: In case the current through the high side DMOS of the
3. Overtemperature protection: In case the junction temperature exceeds a value of
During the transmission the diagnosis function of the IC supervises the antenna current
and frequency and the half-driver bridge supply voltage. If any error is detected at the
end of the transmission cycle the error indication is set (as in circuit protection case).
There are the following diagnosis cases:
1. Under-voltage detection: Monitors if DVCC is below VBAT
2. Antenna frequency errror: Diagnosis if the oscillation frequency during transmis-
3. Antenna peak current error: Diagnosis if the peak current is greater than the
peak
DEB
(typically 31 V).
half-bridge exceeds a value of IOCH or the current through the low side DMOS
of the half-bridge exceeds a value of IOCL typically 2 A).
TSD (typically 165°C).
sion is outside the tracking range 100 kHz to 150 kHz.
adjusted IA
this duty cycle maximum is really 100%. If during the ramp up of the antenna cur-
(typically 20 µs). This debounce filter is activated in case the half-bridge is acti-
PEAK
+ 15% typically.
peak
UV
+ 20% a pulse skipping
(typically 6.5 V).
4739B–AUTO–10/04
LD