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24 SPRUIE6 – April 2017
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AMIC110 Industrial Communications Engine (AMIC110 ICE)
The glue logic is required to ensure the functionality of the AMIC110 boot sequence and to ensure that
two outputs are not driving against each other at startup (the SN74LVC541AD buffer and SN74LVC2G66
dual switch provide this functionality).
Approximately 10 LEDs are used as the status LEDs of the real-time Ethernet protocols. Each LED draws
2 mA of current.
The Flash used is the W25Q64 from Winbond. The worst case current consumption of the W25Q64 is 25
mA according to the device datasheet.
Equation 1 was used to calculate the I/O switching loss of a line connected to a single AMIC110 pin.
P
I/Oout
= (C
OUT
× (V
I/O
)
2
× ƒ ) = 25 MHz × 3.3 V
2
× 20 pF = 5.4 mW (1)
The I/O capacitance is approximated as the typical load capacitance of the PRU pins of the AMIC110, as
specified in the
AMIC110 Sitara™ SoC data sheet. The MII signals have a 25-MHz clock frequency. There
is approximately 1.67 mA of drive current per 3.3-V I/O pin. Approximately 50 pins are used in this design.
Table 14 lists the current consumption requirements of the external circuit and estimated I/O switching
losses.
Table 14. Current Consumption Requirement of External Circuit and I/O Switching Losses
Rail Flash Glue Logic LEDs I/O Switching Losses
3.3 V
≈
25 mA
≈
10 mA
≈
20 mA
≈
83 mA
4.4 Overall System Current Consumption
Table 15 lists the system current requirements.
(1)
DDR3 interface using 1.5 V.
Table 15. System Current Requirements
Rail Sitara DDR3 DP83822 External Circuit
1.1 V ≈ 420 mA
1.5 V
(1)
≈ 120 mA ≈ 140 mA
1.8 V ≈ 33 mA
3.3 V ≈ 34 mA ≈ 159 mA ≈ 138 mA
Table 16 lists the summary of overall current requirements.
(1)
DDR3 interface using 1.5 V.
Table 16. Overall Current Requirements Summary
Rail Current
1.1 V ≈ 420 mA
1.5 V
(1)
≈ 260 mA
1.8 V ≈ 33 mA
3.3 V ≈ 331 mA
4.5 TPS650250 Power Dissipation
The TPS650250 PMIC is designed to provide the required voltages and currents for all power rails of the
AMIC110 processor (see
Powering the AM335x With the TPS650250 ).