MDEV-868-PRC datasheet(20/55 Pages) LINX

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Using the Low Power Features

The module supports a sleep state to save current in battery-powered

applications. During the sleep state, no module activity occurs and no

packets can be received but current consumption is less than 1µA typical.

There are two ways of putting the module to sleep. First, pulling the Power

Down (POWER_DOWN) line low puts the module to sleep. Taking the line

high wakes the module. Second, all of the following should be true:

1. There is no transmission in progress

2. All status lines are low and either

• IDLE = 1 (default) and all status lines are configured as inputs, or

• IDLE = 2 (allows sleeping when incoming control message may be

missed)

3. The internal KeepAlive timer has expired.

The internal KeepAlive timer is set by the following events:

1. On wakeup from a transition on the CMD_DATA_IN line, KeepAlive is

set to 2s. This allows time for an external unit to change IDLE to 0 to

keep the unit awake.

2. On each transmission, KeepAlive is set to 760ms if the remaining

KeepAlive time is less.

[max(760ms, KeepAlive)]

3. On reception of a REMOTE_CONFIRM packet, KeepAlive is

set to received ALIVE value multiplied by 0.1s if the remaining

KeepAlive time is less. The KeepAlive can be extended indefinitely

by periodic reception of REMOTE_CONFIRM messages.

max(REMOTE_CONFIRM.keepAlive * 100ms, KeepAlive)

During sleep mode, the output lines are in the states in Figure 27.

When the POWER_DOWN line is high, the module awakens when a status

line input goes high, the PB line goes high or there is a change on the

CMD_DATA_IN lines. If a negative-going pulse is needed to generate a

rising edge, the pulse width should be greater than 1µs.

If the volatile registers have been corrupted during sleep, a software reset

is performed. This restarts the module as if power were cycled. This can be

caused by power surges or brownout among other things.

Pulsing RESET low causes the module to restart rather than continue from

sleep.

IDLE = 1 is used when the module is an IU only. This puts it to sleep when

all status line inputs are low.

IDLE = 2 is used when the module is primarily an IU, but can accept

activation commands from remote units. In this case, the module stays

asleep until a status line input goes high. While awake, the module can

receive activation commands and will remain awake while commands are

received. As soon as all status line inputs and outputs go low, the module

returns to sleep.

HumPRCTM Series Transceiver Output Line Sleep States

Output Line

Sleep State

S0 - S7 output

Low

LNA_EN

Low

PA_EN

Low

CMD_DATA_OUT

Low

MODE_IND

Low

ACK_OUT

Low

Figure 27: HumPRCTM Series Output Line Sleep States

MDEV-868-PRC Datasheet(PDF) 20 Page - Linx Technologies

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