APT7846 Ver la hoja de datos (PDF) - Anpec Electronics

Número de pieza

componentes Descripción

Fabricante

APT7846

Touch Screen Controller

Anpec Electronics 

APT7846

Chip Overview

The APT7846 is a successive approximation ana-

log-to-digital (A/D) converter based around a capac-

itive redistribution DAC. Figure 1 show basic opera-

tion of the APT7846.

The APT7846 communicates via a 4-wire serial

interface. The device requires an external refer-

ence voltage Vref. The value of the reference volt-

age directly sets the input range of the converter.

Otherwise you can use internal reference Voltage to

do conversion.

The APT7846 primary function is to control resistive

touchscreens. When a touch is detected , pen inter-

rupt pin will go low to wake up extenal microproces-

sor . The microprocessor writes register to initiate

conversion.

This A/D converter may also be used to measure

voltage presented on the IN Pin or to measure bat-

tery presented on the VBAT Pin.

Analog Input

The analog input to the converter is provided via a

four-channel multiplexer. Figure 2 shows a simpli-

fied diagram of the APT7846 with the difference in-

put of the A/D converter , and the converter’s

reference. Table I and Table II also show the rela-

tionship between the A2 , A1 , A0 , SER/,.4 and the

configuration of the APT7846. See the section of

single-ended reference mode and differential refer-

ence mode for more details.

+2.7V to +5v

1uF

to

10uF

(Optional)

To

Touch

Screen

0.1uF

Battery Input

Auxiliary Input

APT7846

1 +Vcc

DCLK 16

2 X+

CS 15

3 Y+

DIN 14

4 X-

BUSY 13

5 Y-

DOUT 12

6 GND

PENIRQ 11

7 VBAT

+Vcc 10

8 IN

VREF 9

0.1uF

Connect to

Microprossor

100k ohm (optional)

FIGURE 1. Basic Operation of the APT7846

Copyright  ANPEC Electronics Corp.

5

Rev. A.6 - Dec., 2001

www.anpec.com.tw

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