FUNCTIONAL DEVICE OPERATION
OPERATING MODES
Table 32. LDO Regulator Control (External Pass Device LDOs)
VxEN
VxMODE
VxSTBY
STANDBY
Regulator Vx
0
1
1
1
1
1
X
0
1
X
0
1
X
0
0
1
1
1
X
X
X
0
1
1
Off
On
Low Power
On
Off
Low Power
Notes
47. This table is valid for regulators with an external pass device
48. STANDBY refers to a Standby event as described earlier
For regulators with internal pass devices and general outputs, the previous table can be simplified.
Table 33. LDO Regulator Control (Internal Pass Device LDOs)
VxEN
VxSTBY
STANDBY
Regulator Vx
0
1
1
1
X
0
1
1
X
X
0
Off
On
On
Off
1
Notes
49. This table is valid for regulators with an internal pass device
50. STANDBY refers to a Standby event as described earlier
BUCK SWITCHERS
Operational modes of the Buck switchers can be controlled by direct SPI programming, altered by the state of the STANDBY
pins, by direct state machine influence, or by load current magnitude when so configured. Available modes include PWM with
No Pulse Skipping (PWM), PWM with Pulse Skipping (PWMPS), Pulse Frequency Mode (PFM), and Off. The transition between
the two modes PWMPS and PFM can occur automatically, based on the load current. Therefore, no specific control is required
to put the switchers in a Low Power mode. When the buck switchers are not configured in the Auto mode, power savings may
be achieved by disabling switchers when not needed, or running them in PFM mode if loading conditions are light enough.
SW1, SW2, SW3, and SW4 can be configured for mode switching with STANDBY or autonomously based on load current with
adaptive mode control (Auto). Additionally, provisions are made for maintaining PFM operation in USEROFF and MEMHOLD
modes to support state retention for faster startup from the low power Off modes for Warm Start or Warm Boot.
Table 34 summarizes the Buck switcher programmability for Normal and Standby modes.
Table 34. Switcher Mode Control for Normal and Standby Operation
SWxMODE[3:0]
Normal mode(51)
Standby Mode(51)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
Off
PWM
PWMPS
PFM
Off
Off
Off
Off
Off
PWM
Auto
NA
Auto
PWMPS
PWMPS
Auto
PFM
PFM
Auto
PWM
PWM
NA
Auto
PWM
PWMPS
PWMPS
Auto
PWM
13892
Analog Integrated Circuit Device Data
Freescale Semiconductor
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