The
AM261xPower Management System
contains a Power Management Unit (PMU), which includes reference voltage generators,
power rail monitors that can trigger a device reset, and a threshold based
temperature monitor. The
AM261x also contains an internal
BIAS LDO, which generates a 1.8-V output on the VDDS18_LDO pin, which should be
externally connected to VDDS18 for IO Bias.
Figure 6-9 shows the different power supply domains in the
AM261x. The
AM261x has the following power
domains, some of which must be externally supplied and some of which are internally
generated by LDO modules in the device.
- 3.3-V IO and analog
Supply: The 3.3-V supply must be provided externally to the VDDS33
and VDDA33 pins and is used for analog logic and IOs.
- 1.8-V OR 3.3-V FLASH IO
Supply: The 1.8V or 3.3V supply must be provided externally to the
VDDSHV_D (VDDS1833_FLASH0) and VDDSHV_E (VDDS1833_FLASH1) pins to set the
Flash IO voltage level. It is used for IO Bias for group Flash0 (OSPI0) and
Flash1 (OSPI1) IOs. For example, if 1.8V IO is required for the OSPI0
peripheral, connect an external 1.8V supply to the VDDSHV_D pin. If 3.3V IO
is required for the OSPI1 peripheral, connect an external 3.3V supply to the
VDDSHV_E pin.
-
Note: VDDSHV_D and VDDSHV_E
pins only exist on the AM261x ZFG, ZEJ, and ZNC package sizes. The
AM261x ZCZ package does not have these configurable power pins, and only
supports 3.3-V logic Flash IO.
- 1.2-V Core Supply: The
1.2-V core supply must be provided externally to the VDD and VDDR1/2/3 pins
and is used for Digital logic and SRAMs.
Note: Industrial-grade
AM261xAO... devices require 1.25-V for the core supply for
operation at 500MHz or 400MHz. Automotive-grade AM261xAL…Q1 and
AM261xAP...Q1 devices require 1.2V for the core supply for
operation at 400MHz.
- 1.8-V IO BIAS Supply:
The 1.8-V IO Bias supply, VDDS18, is generated internally by the BIAS LDO
from the 3.3-V Supply and connect to the VDDS18_LDO pin which can to be
connected to VDDS18 on the board. The supply is used for IO Bias.
- 1.8-V Analog Supply:
The 1.8-V Analog Supply, VDDA18, is generated internally and connected to
the VDDA18_LDO pin which can be connected to VDDA18 and VDDA18_OSC_PLL (1.8V
Analog Supply for PLL) on the board. The supply powers the analog logic and
PLL.
- The 1.8V
Analog Supply can be re-programmed to 1.7V to use for VPP
programming. See Section 6.2.1.1 for more
information.
- VPP 1.7-V Supply: The
1.7-V VPP supply must be provided externally when programming the Fusible
ROM (FROM) present in the device. When the FROM is not being programmed the
1.7-V supply may be disabled or disconnected from the device .
Figure 6-9
AM261x Power Supply
Overview
As a power saving option, the
AM261x supports clock gating for
all the peripherals as well as including a power down feature for On-Chip Static
Random Access Memory (OCSRAM) banks. Details of IP clock gating can be found in
Section 6.2.3.1 and the
power down mode of OCSRAM is explained in Section 6.2.3.2.