SX8674ICSTRT datasheet(39/64 Pages) SEMTECH

39 / 64 page

ADVANCED COMMUNICATIONS & SENSING

Rev 1 – 25

th July 2011

www.semtech.com

SX8674/SX8675/SX8676

Haptics Enabled Multitouch 4/5-Wire

Resistive Touchscreen Controller with Proximity Sensing

Figure 50 – LRA Drive Signal Example

The carrier frequency of VMOUT_Freq is defined as following:

VMOUT_Freq(Hz) = (MIN_Freq / HAPTRANGE)

(PWM mode)

VMOUT_Freq(Hz) = (MIN_Freq / HAPTRANGE) / (HAPTTIMER +1)

(I2C mode)

If AmplitudeCode is within HAPTSQUELCH range (for more than 512/VMOUT_Freq):

VMOUT_Envelope = 0V

Else:

VMOUT_Envelope(V) = (AmplitudeCode / 127) x 1.135 * HAPTGAIN

AmplitudeCode (signed) is defined differently depending on the mode selected (PWM or I2C), see below.

Please note that whatever setting, VMOUT is physically limited to [MVDD;-MVDD], ie saturation effect.

6.3.2

PWM Mode

PWM mode is selected when HAPTMODE = 0.

In this mode, AmplitudeCode is extracted/updated at each MIN period from MIN_DutyCycle:

•

MIN_DutyCycle

≈ 0% => AmplitudeCode = -127

•

…

•

MIN_DutyCycle = 49.6% => AmplitudeCode = -1

•

MIN_DutyCycle = 50% => AmplitudeCode = 0

•

MIN_DutyCycle = 50.4% => AmplitudeCode = +1

•

…

•

MIN_DutyCycle

≈ 100% => AmplitudeCode = +127

6.3.3

I2C Mode

I2C mode is selected when HAPTMODE = 1.

In this mode, AmplitudeCode = HAPTAMP (signed, internally sampled at MIN_Freq). MIN is still used to extract

VMOUT carrier frequency.

6.4

Short-Circuit Protection

The haptics interface integrates a short-circuit protection circuit which detects when MIDD is abnormally high i.e.

above ISHORT.

Under a short-circuit event (HAPTSHORTSTAT=1) the haptics block will stop operation

(MOUTN & MOUTP grounded). When the short-circuit is removed the haptics operations will resume normally.

SX8674ICSTRT датащи(PDF) 39 Page - Semtech Corporation

SX8674ICSTRT датащи(HTML) 39 Page - Semtech Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

датащи скачать

ссылки URL