5.5.1 Reducing Current Consumption
The 2833x and 2823x DSCs incorporate a method to reduce the device current consumption. Because 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 5-3 indicates the typical reduction in current consumption achieved by turning off the clocks.
Table 5-3 Typical Current Consumption by Various Peripherals (at 150 MHz)(1)
(1) All peripheral clocks are disabled upon reset. Writing to or 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.
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.
(4) 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.
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 VDD3VFL rail.
- IDDIO current consumption is reduced by 15 mA (typical) when XCLKOUT is turned off.
- Significant savings in IDDIO 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 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.