11

Definitions

Dynamic Performance Definitions

Fast Fourier Transform (FFT) techniques are used to evaluate

the dynamic performance of the HI3304. A low distortion sine

wave is applied to the input, it is sampled, and the output is

stored in RAM. The data is then transformed into the fre-

quency domain with a 4096 point FFT and analyzed to evalu-

ate the dynamic performance of the A/D. The sine wave input

to the part is -0.5dB down from fullscale for all these tests.

Signal-to-Noise (SNR)

SNR is the measured RMS signal to RMS noise at a speci-

fied input and sampling frequency. The noise is the RMS

sum of all of the spectral components except the fundamen-

tal and the first five harmonics.

Signal-to-Noise + Distortion Ratio (SINAD)

SINAD is the measured RMS signal to RMS sum of all other

spectral components below the Nyquist frequency excluding DC.

Effective Number of Bits (ENOB)

The effective number of bits (ENOB) is derived from the

SINAD data. ENOB is calculated from:

where:

Total Harmonic Distortion (THD)

THD is the ratio of the RMS sum of the first 5 harmonic com-

ponents to the RMS value of the measured input signal.

Operating and Handling Considerations

HANDLING

All inputs and outputs of CMOS devices have a network for

electrostatic protection during handling. Recommended han-

dling practices for CMOS devices are described in

lCAN-6525. “Guide to Better Handling and Operation of

CMOS Integrated Circuits.”

OPERATING

Operating Voltage

During operation near the maximum supply voltage limit, care

should be taken to avoid or suppress power supply turn-on

and turn-off transients, power supply ripple, or ground noise;

any of these conditions must not cause the power supply volt-

ages to exceed the absolute maximum rating.

Input Signals

To prevent damage to the input protection circuit, input signals

is referenced. See Maximum Ratings). Input currents must not

exceed 20mA even when the power supply is off.

Unused Inputs

A connection must be provided at every input terminal. All

Output Short Circuits

Shorting of outputs to any supply potential may damage

CMOS devices by exceeding the maximum device dissipation.

FIGURE 13. TYPICAL HI3304 5-BIT CONFIGURATION

FIGURE 14. IDEAL TRANSFER CURVE

DC

CE2

CLK

CE1

OF

B4

B3

B2

B1

NC

NC

NC

+5V

HI3304

HI3304

ADJUST

CENTER

+5V

1k

Ω

BUFFER

INPUT

+FULL

+5V

CLOCK

B5 MSB

B4

B3

B2

B1

CLK

DC

CE2

CE1

OF

B4

B3

B2

B1

INPUT

SCALE

REF.

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

OVERFLOW

INPUT VOLTAGE

HI3304

HI3304