900844 Datasheet, PDF (50/118 Pages) Freescale Semiconductor, Inc – Integrated Power Management IC for Ultra-mobile and Embedded Applications

FUNCTIONAL DEVICE OPERATION
POWER STATES AND CONTROL
Table 20. RTC Control Registers Structure and Bit Description
Name
Bits
Description
ADJ (ADDR 0x1F - R/W - Default Value: 0x00)
ADJ
Reserved
0 RTC Trim Enable Signal
x0 = Do Not Trim
x1 = Trim
7:1 Fixed to 0000000
TRIM (ADDR 0x20 - R/W - Default Value: 0x00)
TRIMVAL
SIGN
5:0 6-Bit Trim Control
This is a number from 0 to 63 that represents the number of seconds to adjust out of every 64 seconds
6 RTC Calibration Sign Bit
x0 = Add
x1 = Subtract
Reserved
7 Fixed to 0
M32KCLK
CLKOUT (ADDR 0x21 - R/W - Default Value: 0x00)
0 32 kHz clock output mask
x0 = 32 kHz clock output enabled
x1 = 32 kHz clock output masked (disabled)
Reserved
7:1 Fixed to 0000000
POWER STATES AND CONTROL
OVERVIEW
There are three different power states in the operation of the 900844 PMIC:
1. No Power State: No input voltage is available at the
main supply or the coin cell battery input.
2. Active State: The PMIC has enough power to supply
the system.
3. RTC State: The PMIC has enough power to support
the RTC operation and the Keep Alive Registers, but
not enough to power the rest of the system.
The power state of the PMIC at any given time is determined by the conditions of the following inputs:
1. VPWR: This is the main supply to the system. It must
be externally connected to VBAT.
3. VCOINCELL: This is the backup input voltage, typically
from a rechargeable coin cell battery.
2. VBAT: This is the main supply voltage sensing input.
INTERNAL SUPPLIES POWER TREE
Figure 17 shows the 900844 internal power tree.
900844
50
Analog Integrated Circuit Device Data
Freescale Semiconductor