SX8661 datasheet(27/88 Pages) SEMTECH

27 / 88 page

ADVANCED COMMUNICATIONS & SENSING

DATASHEET

Revision v3.2, January 2011

www.semtech.com

SX8661

Low Power, Capacitive Button Touch and Proximity Controller

(8 sensors) with LED Drivers and Analog Output

3.16 Interrupt

3.16.1 Power up

During power up the INTB is kept low. Once the power up sequence is terminated the INTB is cleared

autonomously. The SX8661 is then ready for operation. The AOI levels are updated at the latest one scan period

after the rising edge of INTB.

Figure 23

Power Up vs. INTB

During the power on period the SX8661 stabilizes the internal regulators, RC clocks and the firmware initializes all

registers.

During the power up the SX8661 is not accessible and I2C communications are forbidden. The GPIOs set as

inputs with a pull up resistor.

As soon as the INTB rises the SX8661 will be ready for I2C communication. The GPIOs are then configured

according the parameters in the SPM.

The value of INTB before power up depends on the INTB pull up resistor supply voltage.

3.16.2 Assertion

INTB is updated in Active or Doze mode once every scan period.

The INTB will be asserted at the following events:

• if a Button event occurred (touch or release if enabled). I2C register CapStatLsb show the detailed status of

the Buttons,

• when actually entering Active or Doze mode via a host request (may be delayed by 1 scan period). I2C

• once compensation procedure is completed either through automatic trigger or via host request (may be

delayed by 1 scan period),

• once SPM write is effective (may be delayed by 1 scan period),

• once NVM burn procedure is completed (may be delayed by 1 scan period),

• during reset (power up, hardware RESETB, software reset).

3.16.3 Clearing

The clearing of the INTB is done as soon as the host performs a read to any of the SX8661 I2C registers.

SX8661 Datasheet(PDF) 27 Page - Semtech Corporation