Layout, Grounding, and Bypassing

For best performance, use PC boards. Do not use wire-

wrap boards. Board layout should ensure that digital

and analog signal lines are separated from each other.

Do not run analog and digital (especially clock) signals

parallel to one another or run digital lines underneath

the ADC package.

affect ADC performance. Bypass the supply with a

lead lengths for best supply-noise rejection. If the

power supply is very noisy, connect a 10

Ω resistor in

series with the supply to provide lowpass filtering.

Definitions

Relative Accuracy

Relative accuracy is the deviation of the values on an

actual transfer function from a straight line. This straight

line can be either a best-straight-line fit or a line drawn

between the endpoints of the transfer function, once

offset and gain errors have been nullified. The static lin-

earity parameters for the MAX1298/MAX1299 are mea-

sured using the best-straight-line-fit method.

Differential Nonlinearity (DNL)

Differential nonlinearity is the difference between an

actual step width and the ideal value of 1LSB. A DNL

error specification of less than 1LSB guarantees no

missing codes and a monotonic transfer function.

Offset Error

The offset error is the difference between the ideal and

the actual offset points. For an ADC, the offset point is

the midstep value when the digital output is zero.

Gain Error

The gain or full-scale error is the difference between

the ideal and actual gain points on the transfer function,

after the offset error has been canceled out. For an

ADC, the gain point is the midstep value when the digi-

tal output is full scale.

Aperture Delay

rising edge of the sampling clock and the instant when

an actual sample is taken.

Chip Information

PROCESS: BiCMOS

12-Bit Serial-Output Temperature Sensors

with 5-Channel ADC

18

______________________________________________________________________________________

Figure 8. Remote Diode Shielding for PC Boards

ANODE

SHIELD

CATHODE