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STLC2500

– Identification of the system clock frequency (13 MHz, 26MHz, 19.2 MHz or 38.4 MHz)

– Identification of the low power clock (3.2 KHz, 16.384 KHz, 32 KHz or 32.768 KHz)

Remark: The STLC2500 assumes that the low power clock is available at all times.

7.6

Interrupts

The user can program the GPIOs as external interrupt sources.

7.7

Low power modes

To save power, three low power modes are supported.

Depending of the Bluetooth and of the Host's activity, the STLC2500 autonomously decides to use Deep

Sleep Mode, Sleep Mode or active mode.

Complete Power Down is entered only after an explicit command from the Host.

Table 18. Low power modes

Some examples for the usage of the low power modes:

7.7.1

SNIFF OR PARK

The STLC2500 is in active mode with a Bluetooth connection, once the connection is concluded, SNIFF

or PARK is programmed. Once one of these two states is entered, the STLC2500 goes into Sleep Mode.

After that, the Host may decide to place the STLC2500 in Deep Sleep Mode by putting the UART LINK in

low power mode. The Deep Sleep Mode allows for lower power consumption. When the STLC2500 needs

to send or receive a packet (e.g. at TSNIFF or at the beacon instant), it requires the clock and it goes into

active mode for the needed transmission/reception. Immediately afterwards, it will go back to Deep Sleep

Mode. If some HCI transmission is needed, the UART link will be reactivated, using one of the two ways

explained in 7.8, and the STLC2500 will move from Deep Sleep Mode to Sleep Mode.

7.7.2

INQUIRY/PAGE SCAN

When only inquiry scan or page scan is enabled, the STLC2500 will go in Sleep Mode or Deep Sleep

Mode outside the receiver activity. The selection between Sleep Mode and Deep Sleep Mode depends on

the UART activity like in SNIFF or PARK.

Low power mode

Description

Sleep Mode

The STLC2500:

- Accepts HCI commands from the Host.

- Supports all types of Bluetooth links.

- Can transfer data over Bluetooth links.

- Dynamically switches between sleep and active mode when needed.

- The system clock is still active in part of the design.

- Parts of the chip can be dynamically powered off depending on the Bluetooth activity.

Deep Sleep Mode

The STLC2500:

- Does not accept HCI commands from the Host.

- Supports page- and inquiry scans.

- Supports Bluetooth links that are in Sniff, Hold or Park.

- Does not transfer data over Bluetooth links.

- Dynamically switches between deep sleep and active mode during Bluetooth activity.

- The system clock is not active in any part of the design.

- Parts of the chip can be dynamically powered off depending on the Bluetooth activity.

Complete Power Down

The STLC2500 is effectively powered down:

- No Bluetooth activity is supported.

- The HCI interface is shut down.

- The system clock is not active in any part of the design.

- Most parts of the chip are completely powered off.

- RAM content is not maintained (initialisation is required at wakeup).