CAP1026 datasheet(43/70 Pages) SMSC

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6 Channel Capacitive Touch Sensor with 2 LED Drivers

Datasheet

SMSC CAP1026

Revision 1.1 (08-05-09)

DATASHEET

before the next channel is sampled and the result is averaged over the number of samples measured

before updating the measured results.

For example, if CS1, CS2, and CS3 are sampled during the sensor cycle, and the AVG[2:0] bits are

set to take 4 samples per channel, then the full sensor cycle will be: CS1, CS1, CS1, CS1, CS2, CS2,

CS2, CS2, CS3, CS3, CS3, CS3.

Bit 2 - SAMP_TIME - Determines the time to take a single sample.

‘0’ - The sampling time is ~2.56ms.

‘1’ (default) - The sampling time is ~1.28ms.

Bits 1 - 0 - CYCLE_TIME[1:0] - Determines the overall cycle time for all measured channels during

normal operation as shown in Table 5.17. All measured channels are sampled at the beginning of the

cycle time. If additional time is remaining, then the device is placed into a lower power state for the

remaining duration of the cycle.

APPLICATION NOTE: The programmed cycle time is only maintained if the total averaging time for all samples is

less than the programmed cycle. The AVG[2:0] bits will take priority so that if more samples

are required than would normally be allowed during the cycle time, the cycle time will be

extended as necessary to accommodate the number of samples to be measured.

Table 5.16 AVG Bit Decode

AVG[2:0]

NUMBER OF SAMPLES TAKEN

PER MEASUREMENT

8 (default)

128

Table 5.17 CYCLE_TIME Bit Decode

CYCLE_TIME[1:0]

OVERALL CYCLE TIME

35ms

70ms (default)

105ms

140ms

CAP1026 Datasheet(PDF) 43 Page - SMSC Corporation