1996 Feb 21

9

Philips Semiconductors

Product specification

8-bit, 40 Msps 2.7 to 5.5 V universal

analog-to-digital converter

TDA8790

3. In order to ensure the optimum linearity performance of such converter architecture the lower and upper extremities

of the converter reference resistor ladder (corresponding to output codes 0 and 255 respectively) are connected to

a) The current flowing into the resistor ladder is

and the full-scale input range at the converter,

to cover code 0 to code 255, is

will be kept reasonably constant from part to part. Consequently variation of the output codes

voltage. When several ADCs are connected in parallel and fed with the same reference source, the matching

between each of them is then optimized.

4. The analog bandwidth is defined as the maximum input sine wave frequency which can be applied to the device.

No glitches greater than 2 LSBs, nor any significant attenuation is observed in the reconstructed signal.

5. The analog input settling time is the minimum time required for the input signal to be stabilized after a sharp full-scale

input (square-wave signal) in order to sample the signal and obtain correct output data.

6. Effective bits are obtained via a Fast Fourier Transform (FFT) treatment taking 8 K acquisition points per equivalent

fundamental period. The calculation takes into account all harmonics and noise up to half of the clock frequency

(NYQUIST frequency). Conversion to signal-to-noise ratio: S/N = EB

× 6.02 + 1.76 dB.

7. Measurement carried out using video analyser VM700A, where video analog signal is reconstructed through a DAC.

I

L

V

RT

V

RB

–

R

OB

R

L

R

OT

++

------------------------------------------

=

V

i

R

L

I

L

×

R

L

R

OB

R

L

R

OT

++

------------------------------------------

==

V

RT

V

–

0.838

V

RT

V

RB

–

(

×

=

()

×

R

L

R

OB

R

L

R

OT

++

------------------------------------------

Fig.3 Explanation of note 3.

handbook, halfpage

RLAD

ROT

VRT

VRM

VRB

ROB

code 255

code 0

7

6

9

MGD284

IL

RL