P83CE558EBBSLASHYYY datasheet(17/72 Pages) PHILIPS

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Philips Semiconductors

Preliminary specification

P83CE558/P80CE558/P89CE558

Single-chip 8-bit microcontroller

1996 Aug 06

6.6

Analog/Digital Converter (ADC)

The P8xCE558 A/D Converter is a 10-bit, successive approximation

ADC with 8 multiplexed analog input channels. It additionally

contains a high input impedance comparator, a DAC built with 1024

series resistors and analog switches, registers and control logic.

Input voltage range is from AVref– (typical 0V) to AVref+ (typical +5V).

A set of 8 buffer registers (10-bit) store the conversion results of the

proper analog input channel each.

11 Special Function Registers (SFR) perform the user software

interface to the ADC: a control SFR (ADCON), an analog port

scan-select SFR (ADPSS), 8 input channel related conversion result

SFR with the 8 lower result bits (ADRSL0...ADRSL7), one common

result SFR for the upper 2 result bits (ADRSH). An extra SFR (P5)

allows for reading digital input port data as an alternative function of

the 8 analog input pins.

In order to have a minimum of ADC service overhead in the

microcontroller program, the ADC is able to operate autonomously

within its user configurable autoscan function.

The functional diagram of the ADC is shown in Figure 15.

Feature Overview:

• 10-bit resolution.

• 8 multiplexed analog inputs.

• Programmable autoscan of the analog inputs.

• Bit oriented 8-bit scan-select register to select analog inputs.

• Continuous scan or one time scan configurable from 1 to 8 analog

inputs.

• Start of a conversion by software or with an external signal.

• Eight 10-bit buffer registers, one register for each analog input

channel.

• Interrupt request after one channel scan loop.

• Programmable prescaler (dividing by 2, 4, 6, 8) to adapt to

different system clock frequencies.

• Conversion time for one A/D conversion: 15 µs ... 50 µs

• Differential non-linearity

DLe

±1 LSB.

• Integral non-linearity

ILe

±2 LSB.

• Offset error

OSe

±2LSB.

• Gain error

±0.4 %.

• Absolute voltage error

±3 LSB.

• Channel to channel matching

Mctc

±1LSB.

• Crosstalk between analog inputs : Ct < –60dB. @100 kHz.

• Monotonic and no missing codes.

• Separated analog (AV

DD, AVSS) and digital (VDD, VSS) supply

voltages.

• Reference voltage at two special pins : AV

REF– and AVREF+.

For further information on the ADC characteristics, refer to the

“DC CHARACTERISTICS” section.

6.1.1

Functional description:

Table 9.

A/D Special Function Registers

SYMBOL

NAME

ACCESS

ADCON

A/D control register

read/write

ADPSS

Analog port scan-select register

read/write

ADRSLn

8 A/D result registers, the 8 lower bits (n: 0...7)

read only

ADRSH

A/D result register, the 2 higher bits

read only

Digital input port (shared with analog inputs)

read only

A/D Control Register ADCON

The Special Function Register ADCON contains control and status

bits for the A/D Converter peripheral block. The reset value of

ADCON is (00000000). Its hardware address is D7H. ADCON is not

bit addressable.

ADCON (D7H)

ADPR1

ADPR0

ADPOS

ADINT

ADSST

ADCSA

ADSRE

ADSFE

Figure 14. ADC control register.

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