TLV2556

SLAS355A – DECEMBER 2001 – REVISED SEPTEMBER 2002

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PRINCIPLES OF OPERATION

bipolar output format

D0 in the CFGR1 controls the binary data format used to represent the conversion result. When D0 is cleared

to 0, the conversion result is represented as unipolar (unsigned binary) data. Nominally, the conversion result

When D0 is set to 1, the conversion result is represented as bipolar (signed binary) data. Nominally, conversion

as the sign bit. The bipolar data format is related to the unipolar format in that the MSBs are always each other’s

complement.

Selection of the unipolar or bipolar format always affects the current conversion cycle, and the result is output

during the next I/O cycle. When changing between unipolar and bipolar formats, the data output during the

current I/O cycle is not affected.

reference

The device has a built-in reference with a programmable level of 2.048 V or 4.096 V. If the internal reference

is used, REF+ is set to 2.048 V or 4.096 V and REF– is set to analog GND. An external reference can also be

used through two reference input pins, REF+ and REF–, if the reference source is programmed as external.

The voltage levels applied to these pins establish the upper and lower limits of the analog inputs to produce a

full-scale and zero-scale reading respectively. The values of REF+, REF–, and the analog input should not

exceed the positive supply or be lower than GND consistent with the specified absolute maximum ratings. The

digital output is at full scale when the input signal is equal to or higher than REF+ and at zero when the input

signal is equal to or lower than REF–.