MCP48CMB21 datasheet(99/106 Pages) MICROCHIP

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 2019 Microchip Technology Inc.

DS20006160A-page 99

MCP48CXBXX

FIGURE B-3:

GAIN ERROR AND FULL-

SCALE ERROR EXAMPLE.

EQUATION B-5:

GAIN ERROR EXAMPLE

B.10

Gain Error Drift (EGD)

The Gain Error Drift is the variation in Gain Error due to

a change in ambient temperature. The Gain Error Drift

is typically expressed in ppm/°C (of FSR).

B.11

Integral Nonlinearity (INL)

The Integral Nonlinearity (INL) Error is the maximum

deviation of an actual transfer function from an ideal

transfer function (straight line) passing through the

defined end-points of the DAC transfer function (after

Offset and Gain Errors have been removed).

For the MCP48CXBXX, INL is calculated using the

defined end-points, DAC code 64 and code 4032. INL

can be expressed as a percentage of FSR or in LSb.

INL is also called relative accuracy. Equation B-6 shows

how to calculate the INL error in LSb and Figure B-4

shows an example of INL accuracy.

Positive INL means a VOUT voltage higher than the

ideal one. Negative INL means a VOUT voltage lower

than the ideal one.

EQUATION B-6:

INL ERROR

FIGURE B-4:

INL ACCURACY.

Ideal Transfer

Actual

DAC Input Code

Full-Scale

Error (EFS)

Gain Error (EG)

Function

4032

4095

VREF

Transfer

Function

(@ code = 4032)

Ideal Transfer

Function shifted by

Offset Error

(crosses at start of

defined linear range)

Where:

EG is expressed in % of Full-Scale Range (FSR).

VOUT(@4032) = The measured DAC

output voltage at the

specified code.

VOUT_Ideal(@4032) = The calculated DAC

output voltage at the

specified code.

(4032 * VLSb(Ideal))

VOS = Measured offset voltage.

VFull-Scale Range = Expected Full-Scale

output value (such as the

VREF voltage).

VOUT(@4032) VOS

–

VOUT_Ideal(@4032)

–



VFull-Scale Range

---------------------------------------------------------------------------------------------------- * 100

Where:

INL is expressed in LSb.

VCalc_Ideal = Code * VLSb(Measured) + VOS

VOUT(Code = n) = The measured DAC output

voltage with a given DAC

VLSb(Measured) = For Measured:

(VOUT(4032) - VOUT(64))/3968

VOS = Measured offset voltage

EINL

VOUT VCalc_Ideal

–



VLSb Measured



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

010

001

000

Analog

Output

(LSb)

DAC Input Code

011

111

100 101

110

Ideal Transfer Function

Actual Transfer Function

INL = < -1 LSb

INL = 0.5 LSb

INL = - 1 LSb

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