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Analog Integrated Circuit Device Data
18
Freescale Semiconductor
33389
FUNCTIONAL DEVICE OPERATION
FUNCTIONAL DEVICE OPERATION
Voltage Regulator V1
V1 is a 5.0 V, three percent low drop voltage regulator
dedicated to the microcontroller supply. It can deliver up to
100 mA. It is totally protected against short-to-ground
(current limitation) and over temperature. V1 is active in
Normal Request, Normal, and Stand-by modes.
No forward parasitic diode exists from V1 to VBAT. This
means if VBAT voltage drops below V1, high current flowing
from V1 to VBAT will not discharge the capacitor connected to
V1. Its stored energy will only be used to supply the
microcontroller and gives time to save all relevant data.
Under Voltage Reset—V1 is monitored for under voltage
(power-up, power down) and a reset is provided at RST
output for 1 ms. This ensures proper initialization of the
microcontroller at power-on or after supply is lost.
Furthermore, a flag is set in the Reset Source Register
(RSR) and can be read via the SPI.
Over Temperature Protection—V1 internal ballast
transistor is monitored for over temperature. Two detection
thresholds are provided. A pre-warning threshold at 145°C
and a shut-off threshold at 175°C. Once the first threshold
is reached, a flag is set in the Over Temperature Status
Register (OTSR). A maskable interrupt can be sent to the
microcontroller. Once the second threshold is reached, a
flag is set in the OTSR, a maskable interrupt is sent to the
microcontroller and V1 is switched OFF.
Once the junction temperature is back to the pre-warning
threshold, V1 regulator will be automatically switched ON.
Note: Current capability of V1, V2 and V3 depends upon the thermal
management. Over temperature shutdown might be reached and
lead to turn OFF of V1, V2, and V3 for output current below their
maximum current capability.
Voltage Regulator V2
V2 is a 5.0 V low drop voltage regulator dedicated to
peripherals supply. It can deliver up to 200 mA and is
protected against short to ground (current limitation) and over
temperature. V2 is active in Normal mode.
Under Voltage Detection—V2 is monitored for under
voltage and a flag is set in the Voltage Supply Status
Register (VSSR).
Over Temperature Protection—V2 internal ballast
transistor is monitored for overtemperature. Two detection
thresholds are provided. A pre-warning threshold at 140°C
and a shut-off threshold at 165°C. Once the first threshold
is reached, a flag is set in the readable OTSR register. A
maskable interrupt can be sent to microcontroller.
Once the second threshold is reached, a flag is set in the
OTSR register, V2 is switched OFF. It can only be switched
on again via the SPI.
Switch V3
V3 is a 10
switch to V
BAT. It can be used to supply
external contacts or relays. A great flexibility is given for the
different possible ways for its control. It is protected against
short to ground (current limitation).
Over Temperature Protection—V3 output transistor is
monitored for over temperature. Once the threshold is
reached, a flag is set in the VSSR register, V3 is switched
OFF. It will be automatically switched ON once the junction
temperature is back to the pre-warning threshold.
Table 6. V1 Control
Conditions for V1 ON
Conditions for V1 OFF
Normal Request Mode
(at V1 Power ON)
Sleep Mode (via SPI)
Normal Mode (via SPI)
Shut-Off Temperature Threshold
Reached
Stand-by Mode (via SPI)
No VBAT Power Supply
(cold start)
V1 Below Pre-Warning
Temperature Threshold
Emergency Mode
During Rest
—
Table 7. V2 Control
Conditions for V2 ON
Conditions for V2 OFF
Normal Mode (via SPI) and V2
Below Shut-Off Temperature
Threshold
Sleep, Stand-by, Normal
Request, or Emergency Modes
(via SPI)
—
Shut-Off Temperature Threshold
Reached
—
V1 Disabled (for any reason)
Table 8. V3 Control
Conditions For V3 ON
Conditions For V3 OFF
Permanently in Normal Mode
if Configured via SPI
Permanently in Normal
Mode if Configured
Permanently in Stand-by
Mode if Configured via SPI
Normal Request Mode
In Sleep Mode, During
Enable Time of Cyclic
Sense if Configured
Permanently in Stand-by
Mode if Configured
—
Permanently in Sleep
Mode if Configured