IQS227AS datasheet(13/31 Pages) ETC2

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IQ Switch

ProxSense

® Series

IQS227AS Datasheet

Page 13 of 31

Revision 1.05

October 2015

Configuration: Bank0 bit4-2

TTHR2:TTHR0: Touch Thresholds

Bit

Selection

000

72/256

001

8/256 (Most sensitive)

010

24/256

011

48/256

100

96/256

101

128/256

110

160/256

111

192/256 (Least sensitive)

6.6 Power Modes

The IQS227AS has four power modes

specifically

designed

reduce

current

consumption for battery applications.

The power modes are basically implemented

around the occurrence of charge cycle every

tSAMPLE seconds (refer to Table 6.1). The

fewer charge transfer cycles that need to

occur per second the lower the power

consumption (but decreased response time).

During Boost Power Mode (BP), charge

cycles are initiated approximately every 9ms.

While in any power mode the device will zoom

to BP whenever an existing count sample (CS)

indicates a possible proximity or touch event.

The device will remain in BP for tZOOM seconds

and then return to the selected power mode.

The Zoom function allows reliable detection of

events with counts being produced at the BP

rate.

Table 6.1

Power Mode configuration:

Bank2 bit1-0

Bit

Power Mode timing

tSAMPLE (ms)

tBP (default)

BP (9ms)

tNP

128

tLP1

256

tLP2

512

Zoom to Boost Mode after proximity detected

Charge Cycle

Duration = tCHARGE

tSAMPLE

Figure 6.4

LP Modes: Charge cycles

6.7

Base Values

The sensitivity of the IQS227AS can be

changed by adjusting the base value of the

ATI algorithm, and as a result changing the

compensation required to reach the target.

�� =

��

The target of the IQS227AS is fixed at 1000

counts.

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