prcm-098
WKUP Event
I2C command
VDD1
sys_32k
sys_clkreq
VDD2
SYS_CLK
PRM_CLKSETUP[15:0]SETUPTIME (1)
(stabilization time)
IDLE
VDD2 ON
VDD1 ON
0v
Vopp
PRM_VOLTSETUP1[31:16] SETUPTIME2
0v
Vopp
PRM_VOLTSETUP1[15:0] SETUPTIME1
Public Version
PRCM Basic Programming Model
www.ti.com
•
•
These registers allow controlling the setup time of the VDD1 and VDD2 power supplies when the device
exits the off mode or when the voltage is scaled. It is a constant value that depends on the connected
power IC. At power-up reset, this register is not used, because the external power supply is already
stable. After boot up, the software must set the correct value to ensure proper sequences when
performing voltage scaling or sleep transitions.
The
register has the following bit fields:
•
SETUPTIME1: The setup time of the VDD1 regulator. It is computed as 8 x NbCycles (number of
cycles of the system clock), where NbCycles is configured in the register bit field.
•
SETUPTIME2: The setup time of the VDD2 regulator. It is computed as 8 x NbCycles (number of
cycles of the system clock), where NbCycles is configured in the register bit field.
The
register is used when the device exits the off mode and manages the
sequencing of the voltage regulation steps (the
[3] SEL_OFF bit is set to 0).
The
register has the following bit field:
•
OFFMODESETUPTIME: The number of 32-kHz clock cycles for the overall setup time of the power
management IC when coming back from off mode.
The
register is used only when the device exits off mode and an external power IC
manages the sequencing of the voltages regulation steps (
[3] SEL_OFF is set to 1).
shows off mode wakeup using I
2
C.
Figure 3-88. Off Mode Wakeup Using I
2
C
(1)
[31:16] SETUPTIME2 and
[15:0] SETUPTIME1 are not used during
voltage scaling (between different OPPs).
3.6.5.1.2 PRM_VOLTOFFSET (Voltage Offset Register)
This register allows setting the offset time, which is the time duration between the assertion of sys_clkreq
and the deassertion of sys_off_mode when the device is exiting off mode. This time, set as a number of
32-kHz clock cycles, is used to delay the deassertion of sys_off_mode (and as a consequence, the
voltage ramping) after the clock has been requested. This is done to avoid waiting for the clock to stabilize
420
Power, Reset, and Clock Management
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated