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3.4.3 Power
3.4.3.1 Power Input
The following sections describe the power distribution network topology that supplies the EVM board, supporting
components and reference voltages.
The AM64x/AM243x EVM board includes a power solution based on discrete power supply components. The
initial stage of the power supply will be 12 V from a barrel jack connector with part reference J6. J6 supports 8A
current rating and necessary diodes for reverse polarity protection and voltage surge protection. The 12 V input
(VMAIN) of the EVM that is used to generate all necessary voltages required by the EVM.
A ON/OFF switch with part reference SW1 is provided to turn ON/OFF the EVM by connecting this switch to
Enable pin of LM5140, thereby, allowing the switch to turn on or off the board based on the switch position. The
board is in off condition when switch is grounded position 1-2 and in on condition when the switch is in position
2-3. Additionally GPIO from the test automation header is also connected to the switch to control ON/OFF of the
EVM via the test automation board. A fault indication LED LD5 will be in ON status in case of reverse polarity.
LD6 will be in ON status to indicate VMAIN power good.
Note
The Switch SW1 does not turn of VMAIN. It only disables the VCC_5V0 output of LM5140 from which
all other power supplies are derived.
3.4.3.2 Reverse Polarity Protection
A Schottky barrier rectifier with reference D3 is kept for reverse polarity protection, which has average forward
current: IF(AV) ≤ 15 A, reverse voltage: VR ≤ 45 V. LD6 status will give power polarity.
Table 3-2. VMAIN LED
LED ON Status OFF Status
LD5 Power polarity reversed Power polarity good
LD6 Board Power on Board Power off
3.4.3.3 Current Monitoring
INA226 power monitor devices are used to monitor current and voltage of various power rails of AM64x/AM243x
processor. The INA226 interfaces to the AM64x/AM243x through I2C interface. Four terminal, high precision
shunt resistors are provided to measure load current.
Table 3-3. INA Devices I2C Slave Address
Power Source Supply Net
Slave Address
(IN HEX)
Value of the Shunt Connected
to the Supply Rail
VCC_CORE VDD_CORE 40 2mΩ ±1%
VDD_0V85 VDDAR_CORE 41 10mΩ ± 0.5%
VCC_3V3_SYS SoC_DVDD3V3 4C 10mΩ ± 0.5%
VCC1V8 SoC_DVDD1V8 4B 10mΩ ± 0.5%
VDDA1V8 VDDA_1V8 4E 10mΩ ± 0.5%
VCC1V2_DDR VDD_DDR4 46 10mΩ ± 0.5%
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SPRUJ63 – SEPTEMBER 2022
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AM64x/AM243x EVM User's Guide 13
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