13892 datasheet(64/161 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

13892

FUNCTIONAL DEVICE OPERATION

OPERATING MODES

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.

Table 27. Power Up Sequence

Tap x 2ms

PUMS2 = Open (I,MX37, i.MX51)

PUMS2 = GND (i.MX35, i.MX27)

SW2

SW4

VGEN2

VIOHI

SW4

VGEN2

VIOHI, VSD

SW1

SWBST, VUSB (44)

SW3

SW1

VPLL

VDIG

SW3

VDIG

VUSB (43), VUSB2

VUSB2

Notes

41.

Time slots may be included for blocks which are defined by the PUMS pin as disabled to allow for

potential activation.

42.

The following supplies are not included in the matrix since they are not intended for activation by the

startup sequencer: VCAM, VGEN1, VGEN3, VVIDEO, and VAUDIO. SWBST is not included on the

PUMS2 = Open column.

43.

USB supply VUSB, is only enabled if 5.0 V is present on UVBUS.

44.

SWBST = 5.0 V powers up and so does VUSB regardless of 5.0 V present on UVBUS. By default

VUSB will be supplied by SWBST.

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

45.

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

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