HT86A72 datasheet(43/68 Pages) HOLTEK

43 / 68 page

HT86Axx/HT86ARxx

Rev. 1.10

December 12, 2012

SP+/SP-

AMP_EN

For battery based applications, power consumption is a

key issue, therefore the amplifier should be turned off

when in the standby state. In order to eliminate any

speaker sound bursts while turning the amplifier on, the

application circuit, which will incorporate a capacitance

value of C1, should be adjusted in accordance with the

speaker s audio frequency response. A greater value of

C1 will improve the noise burst while turning on the am-

plifier. The recommended operation sequence is:

Turn On: audio signal standby (1/2VDD)

® enable am-

plifier

® wait tR for amplifier ready ® audio output

Turn Off: audio signal finished

® disable amplifier ®

wait tR for amplifier off

® audio signal off

If the application is not powered by batteries and there is

no problem with amplifier On/Off issues, a capacitor

value of 0.1

mF for C1 is recommended.

Analog to Digital Converter

The need to interface to real world analog signals is a

common requirement for many electronic systems.

However, to properly process these signals by a

microcontroller, they must first be converted into digital

signals by A/D converters. By integrating the A/D con-

version electronic circuitry into the microcontroller, the

need for external components is reduced significantly

with the corresponding follow-on benefits of lower costs

and reduced component space requirements.

A/D Overview

The devices contain a 4-channel analog to digital con-

verter which can directly interface to external analog sig-

nals, such as that from sensors or other control signals

and convert these signals directly into either a 12-bit dig-

ital value.

The following diagram shows the overall internal struc-

ture of the A/D converter, together with its associated

registers.

A/D Converter Data Registers

- ADRL, ADRH

The devices have a 12-bit A/D converter, two registers

are required, a high byte register, known as ADRH , and

a low byte register, known as ADRL. After the conver-

sion process takes place, these registers can be directly

read by the microcontroller to obtain the digitized con-

version value. They use two A/D Converter Data Regis-

ters, note that only the high byte register ADRH utilises

its full 8-bit contents. The low byte register ADRL uti-

lises only 4 of its 8-bit contents as it contains only the

lower 4 bit of the 12-bit converted value.

A D C S o u r c e

f O S C

¸ 2 ~

¸ 3 2

A C S R R e g i s t e r

A D C

V D D

A / D r e f e r e n c e v o l t a g e

A D R L

A D R H

A / D D a t a

R e g i s t e r s

P C R 0 ~ P C R 2

A C S 0 ~ A C S 1

S T A R T E O C

A D C R

R e g i s t e r

P i n C o n f i g u r a t i o n

B i t s

C h a n n e l S e l e c t

B i t s

S t a r t a n d E n d o f

C o n v e r s i o n B i t s

C l o c k D i v i d e R a t i o

P C 0 / A N 0

P C 1 / A N 1

P C 2 / A N 2

P C 3 / A N 3

A/D Converter Structure

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