Siemens EF 88H Series Manual de usuario descargar pdf (Pagina 38)

Semiconductor Group 5 - 3

On-Chip Peripheral Components

5.2 10-bit A/D-Converter

In the SAB 80C517A is a new high performance / high speed 12-channel 10-bit A/D-Converter is

implemented. Its successive approximation techniqe provides 7 µs conversion time (

OSC

=16 MHz).

The conversion principle is upward compatible to the one used in the SAB 80C517. The major

components are shown in figure 5-1.

The comparator is a fully differential comparator for a high power supply rejection ratio and very low

offset voltages. The capacitor network is binary weighted providing 10-bit resolution.

The table 5-1 below shows the sample time

and the conversion time T

(including T

), which

depend on

OSC

and the selected prescaler (see also Bit ADCL in SFR ADCON 1).

Table 5-1, ADC-Convertion Time

OSC

[MHz] Prescaler f

ADC

[MHz] T

[µs] T

[µs]

(incl.

)

12 ÷ 8 1.5 1.33 8

÷ 16 0.75 2.8 16

16 ÷ 8 2.0 2.0 7.0

÷ 16 1.0 4.0 14.0

18÷ 8–––

÷ 16 1.125 3.555 12.4

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 136 137

Sin comentarios

Siemens EF 88H Series Manual de usuario Pagina 38