900844 datasheet(50/118 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

900844

FUNCTIONAL DEVICE OPERATION

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.

2. VBAT: This is the main supply voltage sensing input.

3. VCOINCELL: This is the backup input voltage, typically

from a rechargeable coin cell battery.

INTERNAL SUPPLIES POWER TREE

Figure 17 shows the 900844 internal power tree.

ADJ (ADDR 0x1F - R/W - Default Value: 0x00)

ADJ

RTC Trim Enable Signal

x0 = Do Not Trim

x1 = Trim

Reserved

7:1

Fixed to 0000000

TRIM (ADDR 0x20 - R/W - Default Value: 0x00)

TRIMVAL

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

SIGN

RTC Calibration Sign Bit

x0 = Add

x1 = Subtract

Reserved

Fixed to 0

CLKOUT (ADDR 0x21 - R/W - Default Value: 0x00)

M32KCLK

32 kHz clock output mask

x0 = 32 kHz clock output enabled

x1 = 32 kHz clock output masked (disabled)

Reserved

7:1

Fixed to 0000000

Table 20. RTC Control Registers Structure and Bit Description

Name

Bits

Description

900844 Datasheet(PDF) 50 Page - Freescale Semiconductor, Inc

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