
SPRS457E
– MARCH 2009 – REVISED JUNE 2011
Table 6-1. Power Supplies (continued)
CUSTOMER
TOLERANCE
PACKAGE
DEVICE PLANE
DESCRIPTION
BOARD SUPPLY
PLANE
0 V
VSSA
PLL ground
Note: For proper device operation, keep separate from digital
ground VSS.
0 V
VSSA18_USB
USB ground
0 V
VSSA33_USB
3.3-V USB ground
0 V
VSSA33_VC
3.3-V Voice Codec Module ground
0 V
VSSA18_VC
1.8-V Voice Codec Module ground
0 V
VSSA_ADC
Analog-to-digital converter (ADC) ground
0 V
VSSA18_DAC
1.8-V DAC ground
0 V
VSSA12_DAC
1.2-V DAC ground
VDD18_DDR*0.5
DDR_VREF
DRR reference voltage
(VDDS divided by 2, through board resistors)
0.5V
±5%
VREF
DAC reference voltage
5.25V
USB_VBUS
VBUS
6.4
Power-Supply Sequencing
In order to ensure device reliability, the device requires the following power supply power-on and
power-off sequences. See
Section 5.2, Recommended Operating Conditions, for a description of the
power supplies.
The following power sequences are recommended to prevent damage to the device.
The PRTCSS core must always be powered-on and powered-off regardless of whether the PRTCSS
feature is used.
If the PRTCSS sequencer is to be used in any PRTCSS modes, please refer to the TMS320DM36x
PRTCSS User's Guide (literature number
SPRUFJ0) for more details on the differences to the power
sequence.
6.4.1
Simple Power-On and Power-Off Method
The following steps must be followed in sequential order for the simple power-on method:
1. Power on the PRTCSS/ Main core (1.2-V or 1.35-V).
2. Power on the PRTCSS/Main I/O (1.8-V).
3. Power on the Main/Analog I/O (3.3-V).
Note for simple power-on: RESET must be low until all supplies are ramped up.
The following steps should be followed for the simple power-off method:
1. Power off the Main/Analog I/O (3.3-V).
2. Power off the PRTCSS/Main I/O (1.8-V).
3. Power off the PRTCSS/Main core (1.2-V or 1.35-V).
Notes for simple power-off:
– If RESET is low, steps 2 and 3 may be performed simultaneously.
– If RESET is not low, these steps must be followed sequentially.
6.4.2
Restricted Power-On and Power-Off Method
The following steps should be followed for the restricted power-on method:
1. Power on the PRTCSS/ Main core (1.2-V or 1.35-V).
2. Power on the PRTCSS/Main I/O (1.8-V).
3. Power on the Main/Analog I/O (3.3-V).
Notes for restricted power-on:
78
Peripheral Information and Electrical Specifications
Copyright
2009–2011, Texas Instruments Incorporated