Datasheet

RM46L450

RM46L850

www.ti.com

SPNS184A –SEPTEMBER 2012–REVISED SEPTEMBER 2013

4 System Information and Electrical Specifications

4.1 Device Power Domains

The device core logic is split up into multiple power domains in order to optimize the power for a given

application use case. There are 6 power domains in total: PD1, PD2, PD3, PD5, RAM_PD1, and

RAM_PD2. Refer to Section 1.4 for more information.

PD1 is an "always-ON" power domain, which cannot be turned off. Each of the other power domains can

be turned OFF one time during device initialization as per the application requirement. Refer to the Power

Management Module (PMM) chapter of the device technical reference manual for more details.

NOTE

The clocks to a module must be turned off before powering down the core domain that

contains the module.

NOTE

The logic in the modules that are powered down loses its power completely. Any access to

modules that are powered down results in an abort being generated. When power is

restored, the modules power-up to their default states (after normal power-up). No register or

memory contents are preserved in the core domains that are turned off.

4.2 Voltage Monitor Characteristics

A voltage monitor is implemented on this device. The purpose of this voltage monitor is to eliminate the

requirement for a specific sequence when powering up the core and I/O voltage supplies.

4.2.1 Important Considerations

• The voltage monitor does not eliminate the need of a voltage supervisor circuit to guarantee that the

device is held in reset when the voltage supplies are out of range.

• The voltage monitor only monitors the core supply (VCC) and the I/O supply (VCCIO). The other

supplies are not monitored by the VMON. For example, if the VCCAD or VCCP are supplied from a

source different from that for VCCIO, then there is no internal voltage monitor for the VCCAD and

VCCP supplies.

4.2.2 Voltage Monitor Operation

The voltage monitor generates the Power Good MCU signal (PGMCU) as well as the I/Os Power Good IO

signal (PGIO) on the device. During power-up or power-down, the PGMCU and PGIO are driven low when

the core or I/O supplies are lower than the specified minimum monitoring thresholds. The PGIO and

PGMCU being low isolates the core logic as well as the I/O controls during the power-up or power-down

of the supplies. This allows the core and I/O supplies to be powered up or down in any order.

When the voltage monitor detects a low voltage on the I/O supply, it will assert a power-on reset. When

the voltage monitor detects an out-of-range voltage on the core supply, it asynchronously makes all output

pins high impedance, and asserts a power-on reset. The voltage monitor is disabled when the device

enters a low power mode.

The VMON also incorporates a glitch filter for the nPORRST input. Refer to Section 4.3.3.1 for the timing

information on this glitch filter.

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