13892 datasheet(64/158 Pages) FREESCALE

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FUNCTIONAL DEVICE OPERATION

OPERATING MODES

Analog Integrated Circuit Device Data



Freescale Semiconductor

MC13892

POWER MONITORING

The voltage at BPSNS and BP is monitored by detectors as summarized in Table 28.

The UVDET and BPON thresholds are related to the power on/off events as described earlier in this chapter. The LOBATH

threshold is used as a weak battery warning. An interrupt LOBATHI is generated when crossing the threshold (dual edge). The

LOBATL threshold is used as a low battery detect. An interrupt LOBATLI is generated when dropping below the threshold. The

sense bits are coded in line with previous generation parts.

POWER SAVING

SYSTEM STANDBY

A product may be designed to go into DSM after periods of inactivity, such as if a music player completes a play list and no

further activity is detected, or if a gaming interface sits idle for an extended period. Two Standby pins are provided for board level

control of timing in and out of such deep sleep modes.

When a product is in DSM it may be able to reduce the overall platform current by lowering the switcher output voltage,

disabling some regulators, or forcing some GPO low. This can be obtained by SPI configuration of the Standby response of the

circuits along with control of the Standby pins.

To ensure that shared resources are properly powered when required, the system will only be allowed into Standby when both

the STANDBY and the STANDBYSEC are activated. The states of the Standby pins only have influence in On mode. A command

to transition to one of the Low-power Off states (User Off or Memory Hold, initiated with USEROFFSPI = 1) has priority over

Standby.

Note that the Standby pins are programmable for Active High or Active Low polarity, and that decoding of a Standby event will

take into account the programmed input polarities associated with each pin.

Table 28. BP Detection Thresholds

Threshold in V

Bit setting

Falling Edge

Rising Edge

BPSNS1

BPSNS0

UVDET

LOBATL

LOBATH

BPON

2.55

2.8

3.0

3.2

2.55

2.9

3.1

3.2

2.55

3.0

3.3

3.2

2.55

3.1

3.4

3.2

Notes

57.

Default setting for BPSNS[1:0] is 00. The above specified thresholds are ±50 mV accurate for the indicated edge. A hysteresis is applied

to the detectors on the order of 100 mV. BPON is monitoring BP. UVDET, LOBATL and LOBATH are monitoring BPSNS and thresholds

are correlated.

Table 29. Power Monitoring Summary

BPSNS

BPONS

LOBATHS

LOBATLS

< LOBATL

LOBATL-LOBATH

LOBATH-BPON

>BPON

Table 30. Standby Pin and Polarity Control

STANDBY (Pin)

STANDBYINV (SPI bit)

STANDBYSEC (Pin)

STANDBYSECINV (SPI bit)

STANDBY Control (58)

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