Definition of Package Pinouts

(A1 – A12)

Digital Inputs A12 is the least significant digital

input (LSB) and A1 is the most significant digital input

(MSB)

digital input of all 1s and is zero for a digital input of all 0s

voltage)

on the IC chip for use as the shunt feedback resistor for the

external op amp which is used to provide an output voltage

for the DAC This on-chip resistor should always be used

(not an external resistor) since it matches the resistors in

the on-chip R-2R ladder and tracks these resistors over

temperature

external precision voltage source to the internal R-2R lad-

This is also the analog voltage input for a 4-quadrant multi-

plying DAC application

GND

Ground This is the ground for the circuit

Definition of Terms

Resolution

Resolution is defined as the reciprocal of the

number of discrete steps in the DAC output It is directly

related to the number of switches or bits within the DAC For

has 12-bit resolution

Linearity Error

Linearity error in the maximum deviation

from a

straight line passing through the endpoints of the

DAC transfer characteristic It is measured after adjusting

for zero and full scale Linearity error is a parameter intrinsic

to the device and cannot be externally adjusted

National’s linearity test (a) and the best straight line test (b)

used by other suppliers are illustrated below The best

straight line (b) requires a special zero and FS adjustment

for each part which is almost impossible for the user to

determine The end point test uses a standard zero FS ad-

justment procedure and is a much more stringent test for

DAC linearity

Power Supply Sensitivity

Power supply sensitivity is a

measure of the effect of power supply changes on the DAC

full-scale output

Settling Time

Full-scale current settling time requires zero

to full-scale or full-scale to zero output change Settling time

is the time required from a code transition until the DAC

Full-scale Error

Full-scale error is a measure of the output

error between an ideal DAC and the actual device output

and

unipolar

operation

SCALE

e

adjustable to zero

Differential Non-Linearity

The difference between any

two consecutive codes in the transfer curve from the theo-

retical 1 LSB is differential non-linearity

Monotonic

If the output of a DAC increases for increasing

digital input code then the DAC is monotonic A 12-bit DAC

which is monotonic to 12 bits simply means that input in-

creasing digital input codes will produce an increasing ana-

log output

a) End point test after zero and FS adjust

b) Shifting FS adjust to pass best straight line test

TLH5691 – 3

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