APT7843NI 查看數據表（PDF） - Anpec Electronics

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APT7843NI

Touch Screen Controller

Anpec Electronics 

APT7843

Chip Overview

Analog Input

The APT7843 is a successive approximation analog-

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

redistribution DAC. Figure 1 show basic operation of

the APT7843.

The APT7843 communicates via a 4-wire serial

interface. The device also requires an external refer-

ence voltage Vref. The value of the reference voltage

directly sets the input range of the converter.

The APT7843 primary function is to control resistive

touchscreens. When a touch is detected , pen inter-

rupt pin will go low to wake up extenal microprocess.

The microprocessor writes register to initiate

conversion.

This A/D converter may also be used to measure

voltage presented on the IN3 , IN4 pins.

The analog input to the converter is provided via a

four-channel multiplexer. Figure 2 shows a simplified

diagram of the APT7843 with the difference input of

the A/D converter , and the converter’s reference.

Table I and Table II also show the relationship between

the A2 , A1 , A0 , SER/DFR and the configuration of

the APT7843. See the section of single-ended refer-

ence mode and differential reference mode for more

details.

+2.2V to +5V

1uF

to

10uF

(O ptional)

0.1uF

To

Touch

S c re e n

Auxiliary Input

APT7843

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 IN3

+Vcc 10

8 IN4

VREF 9

0.1uF

Connect to

M icroprossor

100k ohm (optional)

FIGURE 1. Basic Operation of the APT7843

Copyright  ANPEC Electronics Corp.

7

Rev. A.8 - Apr., 2002

www.anpec.com.tw

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