DAC8760IPWPR.B datasheet(36/69 Pages) TI2

36 / 69 page

The time required for the output to slew over a given range can be expressed as Equation 7:

Slew Time =

Output Change

Step Size Update Clock Frequency LSB Size

(7)

where

• Slew Time is expressed in seconds

• Output Change is expressed in amps (A) for IOUT or volts (V) for VOUT

When the slew rate control feature is enabled, all output changes happen at the programmed slew rate. This

configuration results in a staircase formation at the output. If the CLR pin is asserted, the output slews to

the zero-scale value at the programmed slew rate. To verify that the slew operation has completed, read Bit

1 (SR-ON) of the Status Register. The update clock frequency for any given value is the same for all output

ranges. The step size, however, varies across output ranges for a given value of step size because the LSB

size is different for each output range. Figure 8-5 illustrates an example of IOUT slewing at a rate set by the

previously described parameters. In this example for the DAC8760 (LSB size of 305 nA for the 0-mA to 20-mA

range), the settings correspond to an update clock frequency of 6.9 kHz and a step size of 128 LSB. As shown

for the case with no capacitors on CAP1 or CAP2, the steps occur at the update clock frequency (6.9 kHz

corresponds to a period close to 150 µs) and the size of each step is about 38 µA (128 × 305 nA). The slew time

for a specific code change can be calculated using Equation 7.

Time (150 µs/ div)

no cap

3 nF CAP1

3 nF CAP2

10 nF CAP1

10 nF CAP2

C001

0 mA to 20 mA range

SRCLK=1100h

SRSTEP = 111h

Figure 8-5. IOUT vs Time With Digital Slew Rate Control

Apply the desired programmable slew rate control setting prior to updating the DAC data register because

updates to the DAC data register in tandem with updates to the slew rate control registers can create race

conditions that may result in unexpected DAC data.

DAC7760, DAC8760

SBAS528D – JUNE 2013 – REVISED DECEMBER 2021

www.ti.com

Submit Document Feedback

Product Folder Links: DAC7760 DAC8760

DAC8760IPWPR.B Datasheet(PDF) 36 Page - Texas Instruments