phyCORE-OMAP44xx
Part II: PCM-959/phyCORE-OMAP44xx Carrier Board
L-760e_1 © PHYTEC Messtechnik GmbH 2012
101
2.1.3.2.3 Power Management
Switches S4 and S5 on the phyCORE-OMAP44xx Carrier Board support the features of the Power Management IC
on the phyCORE-OMAP44xx. They connect to pins X1C44 (X_PMIC_PREQ2A)and X1C43 (X_PMIC_PREQ3) at the
phyCORE-Connector. Please refer to
to learn more about the power management available on
the phyCORE-OMAP44xx.
S4 Issues a
trigger
signal at pin X1C44 (X_PMIC_PREQ2A) of the phyCORE-OMAP44xx in order to switch power
group 2
1
. Pressing this button will toggle the PREQ2A pin of the PMIC on the phyCORE-OMAP44xx LOW.
S5 Issues a
trigger
signal at pin X1C43 (X_PMIC_PREQ3) of the phyCORE-OMAP44xx in order to switch power
group 31. Pressing this button will toggle the PREQ3 pin of the PMIC on the phyCORE-OMAP44xx LOW.
2.1.3.2.4 Current Measurement
To facilitate current measurement at each voltage domain resistors R222 to R227 are provided as current access
measurement points. To calculate the current draw the resulting voltage drop across the shunt resistors must
be measured.
lists the voltage domains and the associated shunt resistors as well as the resistor values.
The shunt resistors chosen are small enough to not affect the output voltage (it will be reduced by the voltage
drop across the shunt), but large enough to have a discernible measurement from general noise.
1.
All special functions of the PMIC such as use of power groups, etc. require the PMIC to be programmed via I
2
C interface. At the time
of delivery only the generation of the required voltages is implemented . Please refer to the TWL6030 Technical Ref. Man. for more
information on how to program the PMIC.
Note:
Signal X_PMIC_PREQ2A is also connected to the power management event signal (PME) of the Ethernet
controller on the phyCORE-OMAP44xx. Please read
to get to know how to avoid conflicts when
using switch S4.
Voltage domain
Shunt resistor
Value
VCC_5V
R226, R227
0,07 Ohm||0,07 Ohm => 0,035 Ohm
VCC_3V3
R224, R225
0,07 Ohm||0,07 Ohm => 0,035 Ohm
VCC_1V8
R222
0,07 Ohm
VCC_1V2
R223
0,07 Ohm
Table 46:
Resistor Values for Current Measurement