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4952J–AUTO–03/11
Atmel ATA6836
3.2 Power-supply Fail
In case of undervoltage at pin VS, an internal timer is started. When during a permanent
undervoltage the delay time (t
dUV
) is reached, the power supply fail bit (PSF) in the output reg-
ister is set and all outputs are disabled. When normal voltage is present again, the outputs are
enabled immediately. The PSF bit remains high until it is reset by the SRR bit in the input
register.
3.3 Open-load Detection
If the open-load detection bit (OLD) is set to low, a pull-up current for each high-side switch
and a pull-down current for each low-side switch is turned on (open-load detection current
I
HS1-6
, I
LS1-6
). If V
VS
–V
HS1-6
or V
LS1-6
is lower than the open-load detection threshold
(open-load condition), the corresponding bit of the output in the output register is set to high.
Switching on an output stage with OLD bit set to low disables the open load function for this
output.
3.4 Overtemperature Protection
If the junction temperature exceeds the thermal prewarning threshold, T
jPW
set, the tempera-
ture prewarning bit (TP) in the output register is set. When the temperature falls below the
thermal prewarning threshold, T
jPW
reset, the bit TP is reset. The TP bit can be read without
transferring a complete 16-bit data word: with CS = high to low, the state of TP appears at pin
DO. After the microcontroller has read this information, CS is set high and the data transfer is
interrupted without affecting the state of the input and output registers.
If the junction temperature exceeds the thermal shutdown threshold, T
j switch off
, the outputs are
disabled and all bits in the output register are set high. The outputs can be enabled again
when the temperature falls below the thermal shutdown threshold, T
j switch on
, and when a high
has been written to the SRR bit in the input register. Thermal prewarning and shutdown
threshold have hysteresis.
3.5 Short-circuit Protection
The output currents are limited by a current regulator. Current limitation takes place when the
overcurrent limitation and shutdown threshold (I
HS1-6
, I
LS1-6
) are reached. Simultaneously, an
internal timer is started. The shorted output is disabled when during a permanent short the
delay time (t
dSd
) programmed by the short-circuit timer bit (SCT) is reached. Additionally, the
short-circuit detection bit (SCD) is set. If the temperature prewarning bit TP in the output regis-
ter is set during a short, the shorted output is disabled immediately and SCD bit is set. By
writing a high to the SRR bit in the input register, the SCD bit is reset and the disabled outputs
are enabled.
3.6 Inhibit
There are two ways to inhibit the Atmel
®
ATA6836:
• Set bit SI in the input register to 0
• Switch pin INH to 0V
In both cases, all output stages are turned off but the serial interface stays active. The output
stages can be activated again by bit SI = 1 (when INH = VCC) or by pin INH switched back to
VCC (when SI = 1).
