7.4.5.1.2 Programmable Slew-Rate Control
When the DAC data registers are written, the voltage on DAC output (V
OUT
) immediately transitions to the new
code following the slew rate and settling time specified in the
Electrical Characteristics
.
The slew rate control feature allows the user to control the rate at which the output voltage (V
OUT
) changes.
When this feature is enabled (using the SLEW-RATE-X[3:0] bits), the DAC output changes from the current
code to the code in the DAC-X-MARGIN-HIGH or DAC-X-MARGIN-LOW registers (when margin high or low
commands are issued to the DAC) using the step size and time-period per step set in CODE-STEP-X and
SLEW-RATE-X bits in the DAC-X-FUNC-CONFIG register:
• SLEW-RATE-X defines the time-period per step at which the digital slew updates.
• CODE-STEP-X defines the number of LSBs by which the output value changes at each update, for the
corresponding channels.
and
show different settings available for CODE-STEP-X and SLEW-RATE-X. With the
default slew rate control setting of no-slew, the output changes immediately at a rate limited by the output drive
circuitry and the attached load.
When the slew rate control feature is used, the output changes happen at the programmed slew rate.
shows that this configuration results in a staircase formation at the output. Do not write to CODE-STEP-X,
SLEW-RATE-X, or DAC-X-DATA during the output slew operation.
calculating the slew time (t
SLEW
).
MARGIN-LOW
MARGIN-HIGH
TIME PERIOD
CODE-STEP
t
SLEW
Figure 7-10. Programmable Slew-Rate Control
t
SLEW
=
SLEW_RATE × MARGIN_HIGH − MARG 1
CODE_STEP
(5)
where:
• SLEW_RATE is the SLEW-RATE-X setting specified in
• CODE_STEP is the CODE-STEP-X setting specified in
.
• MARGIN_HIGH is the DAC-X-MAGIN-HIGH specified in
• MARGIN_LOW is the DAC-X-MAGIN-LOW specified in
SLASF47 – MAY 2022
Copyright © 2022 Texas Instruments Incorporated
35
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