SM320F28335PTPMEP Datasheet, PDF (103/167 Pages) Texas Instruments – Digital Signal Controller (DSC)

SM320F28335-EP
www.ti.com
SPRS581D – JUNE 2009 – REVISED MAY 2012
6.4.1 Reducing Current Consumption
The F28335 DSC incorporates a method to reduce the device current consumption. Since each peripheral
unit has an individual clock-enable bit, reduction in current consumption can be achieved by turning off the
clock to any peripheral module that is not used in a given application. Furthermore, any one of the three
low-power modes could be taken advantage of to reduce the current consumption even further. Table 6-2
indicates the typical reduction in current consumption achieved by turning off the clocks.
Table 6-2. Typical Current Consumption by Various
Peripherals (at 150 MHz)⁽¹⁾
PERIPHERAL
MODULE
ADC
I_DD CURRENT
REDUCTION/MODULE (mA)⁽²⁾
8 ⁽³⁾
I2C
2.5
eQEP
5
ePWM
5
eCAP
2
SCI
5
SPI
4
eCAN
8
McBSP
7
CPU - Timer
XINTF
2
10 ⁽⁴⁾
DMA
10
FPU
15
(1) All peripheral clocks are disabled upon reset. Writing to/reading from
peripheral registers is possible only after the peripheral clocks are
turned on.
(2) For peripherals with multiple instances, the current quoted is per
module. For example, the 5 mA number quoted for ePWM is for one
ePWM module.
(3) This number represents the current drawn by the digital portion of
the ADC module. Turning off the clock to the ADC module results in
the elimination of the current drawn by the analog portion of the ADC
(I_DDA18) as well.
(4) Operating the XINTF bus has a significant effect on IDDIO current. It
will increase considerably based on the following:
• How many address/data pins toggle from one cycle to another
• How fast they toggle
• Whether 16-bit or 32-bit interface is used and
• The load on these pins.
Following are other methods to reduce power consumption further:
• The Flash module may be powered down if code is run off SARAM. This results in a current reduction
of 35 mA (typical) in the V_DD3VFL rail.
• I_DDIO current consumption is reduced by 15 mA (typical) when XCLKOUT is turned off.
• Significant savings in I_DDIO may be realized by disabling the pullups on pins that assume an output
function and on XINTF pins. A savings of 35 mW (typical) can be achieved by this.
The baseline I_DD current (current when the core is executing a dummy loop with no peripherals enabled) is
165 mA, (typical). To arrive at the I_DD current for a given application, the current-drawn by the peripherals
(enabled by that application) must be added to the baseline I_DD current.
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Electrical Specifications 103