Linear Technology LT3695 Series, Datasheet

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LT3695 Series
23
3695fa
APPLICATIONS INFORMATION
Table 5: Effects of Pin Shorts
PINS EFFECT
PGND-DA No effect if V
IN
< V
IN(MAX)
. See Input Voltage Range section for description of V
IN(MAX)
.
SW-RUN/SS The result of this short depends on the load resistance and on R3 (Figure 10). See the following discussion.
RUN/SS-RT No effect or V
OUT
will fall below regulation voltage if I
R3
(Figure 10) < 1mA.
RT -SYNC No effect or V
OUT
will fall below regulation voltage if the current into the RT pin is less than 1mA.
SYNC-V
IN
No effect if V
IN
does not exceed the absolute maximum voltage of SYNC (20V).
PG-GND No effect.
GND-BD (LT3695) V
OUT
may fall below regulation voltage, power dissipation of the power switch will be increased. Note that this short also
grounds the voltage source supplying BD. Make sure it is safe to short the supply for BD to ground. For this reason BD should
not be connected to V
IN
, but it is safe to connect it to V
OUT
.
BD-BOOST (LT3695) If diode D2 (see Figure 10) is used, no effect or V
OUT
may fall below regulation voltage. Otherwise the device may be damaged.
GND-OUT2
(LT3695-3.3, LT3695-5) V
OUT
will fall below regulation voltage, because this shorts the output to ground. As a result, the power dissipation of the part
may increase.
Table 6: Effects of Floating Pins
PIN EFFECT
PGND No effect if the Exposed Pad is soldered.
Otherwise: V
OUT
may fall below regulation voltage. Make sure that V
IN
< V
IN(MAX)
(see Input Voltage Range section for details)
and provide a bypass resistor at the DA pin. See the following discussion.
DA V
OUT
may fall below regulation voltage. Make sure that V
IN
< V
IN(MAX)
(see Input Voltage Range section for details) and provide
a bypass resistor. See the following discussion.
SW V
OUT
will fall below regulation voltage.
RUN/SS V
OUT
will fall below regulation voltage.
RT V
OUT
will fall below regulation voltage.
SYNC V
OUT
may fall below regulation voltage. A fl oating SYNC pin confi gures the LT3695 for pulse-skipping mode. However, a
fl oating SYNC pin is sensitive to noise which can degrade device performance.
V
IN
V
OUT
will fall below regulation voltage.
V
C
V
OUT
may fall below regulation voltage. Disconnecting the V
C
pin alters the loop compensation and potentially degrades device
performance. The output voltage ripple will increase if the part becomes unstable.
FB (LT3695) V
OUT
will fall below regulation voltage.
PG No effect.
GND Output maintains regulation, but potential degradation of device performance.
BD (LT3695) V
OUT
may fall below regulation voltage. If BD is not connected, the boost capacitor cannot be charged and thus the power
switch cannot saturate properly, which increases its power dissipation.
OUT1, OUT2
(LT3695-3.3, LT3695-5) No effect.
BOOST V
OUT
may fall below regulation voltage. If BOOST is not connected, the boost capacitor cannot be charged and thus the power
switch cannot saturate properly, which increases its power dissipation.