FUNCTIONAL DEVICE OPERATION
OPERATING MODES
Table 27. Power Up Sequence
Tap x 2ms
PUMS2 = Open (I,MX37, i.MX51)
PUMS2 = GND (i.MX35, i.MX27)
0
1
2
3
4
5
6
7
8
9
SW2
SW2
VGEN2
SW4
SW4
VIOHI
VGEN2
VIOHI, VSD
SWBST, VUSB (44)
SW1
SW1
SW3
VPLL
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.
POWER MONITORING
The voltage at BPSNS and BP is monitored by detectors as summarized in Table 28.
Table 28. BP Detection Thresholds
Threshold in V
Bit setting
Falling Edge
LOBATL
Rising Edge
BPON
BPSNS1
BPSNS0
UVDET
LOBATH
0
0
1
1
0
1
0
1
2.55
2.55
2.55
2.55
2.8
2.9
3.0
3.1
3.0
3.1
3.3
3.4
3.2
3.2
3.2
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.
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 29. Power Monitoring Summary
BPSNS
BPONS
LOBATHS
LOBATLS
< LOBATL
0
0
0
1
0
0
1
1
1
0
0
0
LOBATL-LOBATH
LOBATH-BPON
>BPON
13892
Analog Integrated Circuit Device Data
Freescale Semiconductor
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