TMS320F28335, TMS320F28334, TMS320F28332
TMS320F28235, TMS320F28234, TMS320F28232
Digital Signal Controllers (DSCs)
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SPRS439C–JUNE 2007–REVISED FEBRUARY 2008
6.4.1 Reducing Current Consumption
Like 280x and 281x, the F2833x/F2823x DSCs incorporate a unique method to reduce the device current
consumption. Since each peripheral unit has an individual clock-enable bit, significant 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 6-3 indicates the typical reduction in current consumption
achieved by turning off the clocks.
Table 6-3. Typical Current Consumption by Various
Peripherals (at 150 MHz)(1)
PERIPHERAL
MODULE
IDD CURRENT
REDUCTION (mA)
ADC
I2C
8(2)
2.5
5
eQEP
ePWM
eCAP
SCI
5
2
5
SPI
4
eCAN
McBSP
CPU - Timer
XINTF
DMA
8
7
2
10(3)
10
15
FPU
(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) 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 (IDDA18) as well.
(3) 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.
Other methods to reduce power consumption further are as follow:
•
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 VDD3VFL rail.
•
IDDIO current consumption is reduced by 15 mA (typical) when XCLKOUT is turned off.
The baseline IDD current (current when the core is executing a dummy loop with no peripherals enabled) is
165 mA, (typical). To arrive at the IDD current for a given application, the current-drawn by the peripherals
(enabled by that application) must be added to the baseline IDD current.
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