AS3658_07 Datasheet, PDF (135/158 Pages) ams AG – Power and Audio Management Unit for Portable Devices

AS3658
Data Sheet Confidential - Detailed Description - System Functions
10.5 Protection Functions
All LDO’s, the DCDC step ups and DCDC step downs have an integrated overcurrent protection. An overtemperature
protection of the chip is also integrated which can be switched on with the serial interface signal temp_pmc_on
(enabled by default; it is not recommended to disable the overtemperture protection). The chip has two signals for the
serial interface: ov_temp_110 and ov_temp_140. The flag ov_temp_110 is automatically reset if the overtemperature
condition is removed, whereas ov_temp_140 has to be reset by the serial interface with the signal rst_ov_temp_140.
If the flag ov_temp_140 is set, an automatic reset of the complete chip is initiated. The flag ov_temp_140 is not
affected by this reset cycle allowing the software to detect the reason for this unexpected shutdown.
lid ^{Table 154. Overtemperature Detection}
Symbol
Parameter
Min Typ Max Unit
Note
a ^T110
ov_temp_110 rising
threshold
95
110 125
ºC
v ^T140
ov_temp_140 rising
threshold
125
140
155
ºC
ill ^{ov_temp_110 and}
T_hyst
ov_temp_140
5
ºC
hysteresis
t _{Table 155. Overtermperature detection Bit definition}
G _{s Addr:106}
Overtemperature Control
These bits control the startup and are set by factory test
A ^t _Bit
Bit Name
Default Access
Description
s ^{n Switch on / off of temperature supervision; default: on}
0
temp_pmc_on
1
R/W
– all other bits are only valid if set to ‘1’
e^{Leave at 1, do not disable}
m ^{t 1}
ov_temp_110
NA
R
Flag that the overtemperature threshold 1 (T₁₁₀) has
been reached
a ^{nFlag that the overtemperature threshold 2 (T140) has}
o ²
ov_temp_140
NA
R
been reached – this flag is not reset by a
overtemperature caused reset and has to be reset by
rst_ov_temp_140
c If the overtemperature threshold 2 has been reached,
l ³
rst_ov_temp_140
0
W
the flag ov_temp_140 is set and a reset cycle is
started. ov_temp_140 should be reset by writing 1 and
afterward 0 to rst_ov_temp_140
a _{10.5.1 Temperature Supervision}
ic ^{A temperature sensor is implemented to provide over-temperature protection of the chip. It generates two flags linked}
to the two temperature thresholds (110 degrees, 140 degrees). Both thresholds have an hysteresis to prevent
oscillation effects.
n _{First threshold (110 degrees) sets the flag ov_temp_110, signalling the serial interface part and software the 110}
h ^{degrees overtemperature condition. If enabled (ovtmp_int_mask=0), an interrupt can be send (interrupt ‘ovtmp’). Thus}
software can react and can shutdown power consuming functions to decrease temperature.
c _{The second threshold (140 degrees) initiates a reset cycle and sets ov_temp_140: this sets all regulators into power-}
down mode and stops charging, and performs the reset cycle of the AS3658.
Te ^{rst_ov_temp_140 flag}
In case of overtemperature and an activated reset (temp_pmc_on=1), the system loses any information about the error
which activated the reset state. Therefore, a flag is implemented, which indicates that the reset was caused by
overtemperature activation (ov_temp_140 is set). This flag is only resetable by writing ‘1’ to rst_ovtemp_140.
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