900844 Datasheet, PDF (84/118 Pages) Freescale Semiconductor, Inc – Integrated Power Management IC for Ultra-mobile and Embedded Applications

FUNCTIONAL DEVICE OPERATION
POWER SUPPLIES
Table 48. Ramp Rate Control Registers (Freescale Defined)
Name
Bits
Description
VDDQTONT
5:4 ^{Turn On Time Settings for VDDQ Regulator}
x0 = 240 μs
x1 = 120 μs
x2 = 60 μs
x3 = 30 μs
RSVD
7:6 RSVD
V21TONT
FSLTONTCNTL2 (ADDR 0x1CB - R/W - Default Value: 0xAA)
1:0 ^{Turn On Time Settings for V21 Regulator}
x0 = 320 μs
x1 = 160 μs
x2 = 80 μs
x3 = 40 μs
V15TONT
3:2 Turn On Time Settings for V15 Regulator
x0 = 200 μs
x1 = 100 μs
x2 = 50 μs
x3 = 25 μs
Reserved
7:4 ^Reserved
POWER SUPPLIES FAULT MANAGEMENT
This section discusses faults related to, or caused by power supplies (directly or indirectly) operating outside their specified
boundaries.
Reference Interrupt Controller for more information on the various interrupt signals, and the interrupt mechanism used to
communicate to the system controller.
THERMAL MANAGEMENT
The thermal protection is based on a circuit with a voltage output that is proportional to the absolute temperature. This voltage
can be read out via the ADC for precise temperature readouts. See ADC Subsystem.
This voltage is monitored by an integrated comparator. Interrupt THRM will be generated, if not masked, when crossing the
thermal warning threshold TWARN, and sets the VRFAULT 1st level interrupt that causes the PMICINT pin to assert, notifying
the system controller of a system event.
In addition to the previous, the 900844 includes integrated thermal protection that shuts down and powers off the system, in
cases of over dissipation, if the junction temperature exceeds the TSHUTDOWN threshold. This thermal protection will act above
the maximum junction temperature, to avoid any unwanted power downs. The protection is de-bounced by one period of the
32 kHz clock in order to suppress any (thermal) noise. This protection should be considered as a fail-safe mechanism. Therefore,
the application design should execute a thermal shutdown under normal conditions.
Once the thermal event is cleared and the temperature is back to its normal range, the 900844 restarts automatically, by
following the steps outlined in Initial Power Up Sequence
Table 49. Thermal Warning/Shutdown Thresholds
Parameter
Min
Typ
Max
Unit
Thermal Warning Threshold
Thermal Warning Hysteresis
Thermal Shutdown Threshold
115
120
125
°C
2
-
4
°C
130
140
150
°C
900844
84
Analog Integrated Circuit Device Data
Freescale Semiconductor