Datasheet

ISET
LIMmin
40 kΩ Amps
R =
I
´
min
typ
max
1800
1600
1400
1200
1000
800
600
400
200
0
ILIMHV/V3P3 - A
0 50 100 150 200 250 300 350 400 450
RISET_S0/S3/V3P3 - W
min
typ
max
0 50 100 150 200 250 300 350 400 450
RISET_S0/S3/V3P3 - W
60%
50%
40%
30%
20%
10%
0%
% - variance from min - A
TPS22980
www.ti.com SLVSB61C –DECEMBER 2011–REVISED SEPTEMBER 2013
Figure 4. I
LIM
vs R
SET
for VHV and V3P3 Figure 5. Percent Variance from min I
LIM
vs R
SET
Figure 4 shows the minimum, typical, and maximum current limit for either supply versus its corresponding R
ISET
value. Equation 1 is used to determine the R
ISET
needed to set a minimum ILIM for a given supply and mode.
Figure 5 shows the approximate variation from the set minimum I
LIM
value to the typical and maximum I
LIM
values.
(1)
where:
R
ISET
= external resistor used to set the current limit for V3P3, VHV (S0), or VHV (S3), and
I
LIMmin
= current limit for V3P3, VHV (S0), or VHV (S3) set by the external R
ISET
resistor.
Each resistor is placed between the corresponding ISET pin and GND, as shown in Figure 3, providing a
minimum current limit between 100mA and 1.5A.
TRANSITION DELAYS
Output transitions of the TPS22980 voltages are shown in Figure 6. When the device transitions from VHV to
V3P3 at the output, the power switches both turn off until the output falls to near the V3P3 voltage. During this
time, a discharge current (IDIS) pulls OUT down. If a load on the line is also pulling OUT down, the output can
drop to 0V due to the switch off time of T3P3OFF. Figure 7 shows the voltage drop on the output during this
transition with no output capacitance.
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