Datasheet

0.957
ILIM
ILIM
1.056
ILIM
52850V
OSmax
R k
56000V
OSnom
R k
61200V
OSmin
R k
I (mA) =
I (mA) =
I (mA) =
W
W
W
R – CurrentLimitResistor – k
ILIM
Ω
0
250
500
750
1000
1250
1500
1750
2000
2250
2500
2750
3000
20 30 40 50 60 70 80 90 100 110 120 130 140 150
Current-Limit Threshold (mA)
I
OS(min)
I
OS(typ)
I
OS(max)
TPS2560
TPS2561
SLVS930A – DECEMBER 2009– REVISED FEBRUARY 2012 www.ti.com
APPLICATION INFORMATION
INPUT AND OUTPUT CAPACITANCE
Input and output capacitance improves the performance of the device; the actual capacitance should be
optimized for the particular application. For all applications, a 0.1μF or greater ceramic bypass capacitor between
IN and GND is recommended as close to the device as possible for local noise decoupling. This precaution
reduces ringing on the input due to power-supply transients. Additional input capacitance may be needed on the
input to reduce voltage overshoot from exceeding the absolute maximum voltage of the device during heavy
transient conditions. This is especially important during bench testing when long, inductive cables are used to
connect the evaluation board to the bench power supply.
Output capacitance is not required, but placing a high-value electrolytic capacitor on the output pin is
recommended when large transient currents are expected on the output.
PROGRAMMING THE CURRENT-LIMIT THRESHOLD
The overcurrent threshold is user programmable via an external resistor, R
ILIM
. R
ILIM
sets the current-limit
threshold for both channels. The TPS2560/61 use an internal regulation loop to provide a regulated voltage on
the ILIM pin. The current-limit threshold is proportional to the current sourced out of ILIM. The recommended 1%
resistor range for R
ILIM
is 20 kΩ ≤ R
ILIM
≤ 187 kΩ to ensure stability of the internal regulation loop. Many
applications require that the minimum current limit is above a certain current level or that the maximum current
limit is below a certain current level, so it is important to consider the tolerance of the overcurrent threshold when
selecting a value for R
ILIM
. The following equations calculates the resulting overcurrent threshold for a given
external resistor value (R
ILIM
). The traces routing the R
ILIM
resistor to the TPS2560/61 should be as short as
possible to reduce parasitic effects on the current-limit accuracy.
(1)
Figure 18. Current-Limit Threshold vs. R
ILIM
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