MMPF0100NPEP datasheet(103/137 Pages) FREESCALE

103 / 137 page

Analog Integrated Circuit Device Data



Freescale Semiconductor

103

PF0100

Functional Block Requirements and Behaviors

Power Generation

6.4.7.1

Coin Cell Battery Backup

The LICELL pin provides for a connection of a coin cell backup battery or a “super” capacitor. If the voltage at VIN goes below

the VIN threshold (VTL1 and VTL0), contact-bounced, or removed, the coin cell maintained logic will be powered by the voltage

applied to LICELL. The supply for internal logic and the VSNVS rail will switch over to the LICELL pin when VIN goes below VTL1

or VTL0, even in the absence of a voltage at the LICELL pin, resulting in clearing of memory and turning off of VSNVS.

Applications concerned about this behavior can tie LICELL pin to any system voltage between 1.8 V and 3.0 V. A small capacitor

should be placed from LICELL to ground under all circumstances.

Coin Cell Charger Control

The coin cell charger circuit will function as a current-limited voltage source, resulting in the CC/CV taper characteristic typically

used for rechargeable Lithium-Ion batteries. The coin cell charger is enabled via the COINCHEN bit while the coin cell voltage is

programmable through the VCOIN[2:0] bits on register COINCTL on Table 111. The coin cell charger voltage is programmable.

In the ON state, the charger current is fixed at ICOINHI. In Sleep and Standby modes, the charger current is reduced to a typical

A. In the OFF state, coin cell charging is not available as the main battery could be depleted unnecessarily. The coin cell

charging will be stopped when VIN is below UVDET.

External Components

Table 110. Coin Cell Charger Voltage

VCOIN[2:0]

VCOIN (V)(72)

000

2.50

001

2.70

010

2.80

011

2.90

100

3.00

101

3.10

110

3.20

111

3.30

Notes

72.

Coin cell voltages selected based on the

type of LICELL used on the system.

Table 111. Register COINCTL - ADDR 0x1A

Name

Bit #

R/W

Default

Description

VCOIN

2:0

R/W

0x00

Coin cell charger output voltage selection.

See Table 110 for all options selectable through

these bits.

COINCHEN

R/W

0x00

Enable or disable the Coin cell charger

UNUSED

7:4

–

0x00

UNUSED

Table 112. Coin Cell Charger External Components

Component

Value

Units

LICELL Bypass Capacitor

100

LICELL Bypass Capacitor as coin cell replacement

4.7

F

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