LT8697
applicaTions inForMaTion
size, input voltage, and output voltage. Since the syn-
chronization frequency will not change the slopes of the
inductor current waveform, if the inductor is large enough
to avoid subharmonic oscillations at the frequency set by
RT, then the slope compensation will be sufficient for all
synchronization frequencies.
currentwhenheldabove9V.Aminimum10kR
resistor
CDC
mustbetiedfromUSB5VtoV
forrobustoperationwith
OUT
V
above its regulation point. The remaining pins SW,
ISP, ISN, PG and SYS tied at or near the output voltage
have at least a 30V maximum rating. The output capacitor
OUT
C
absorbs ESD events on the LT8697 output.
OUT
If V is held low or floated while V
is held high, the
IN
OUT
Output Short Protection
body diode of the LT8697 internal top power switch will
TheLT8697willtolerateashortedoutput.Severalfeatures
are used for protection during output short-circuit and
brownout conditions. The first is the switching frequency
will be folded back while the output is lower than the set
point to maintain inductor current control. Second, the
bottom switch current is monitored such that if inductor
current is beyond safe levels, switching of the top switch
willbedelayeduntiltheinductorcurrentfallstosafelevels.
conduct high current from the SW pin to the V pin,
regardless of the state of the EN/UV pin, causing damage
IN
to the LT8697. V
IN
must remain equal to or lower than
OUT
V to avoid this damage to the LT8697.
PCB Layout
For proper operation and minimum EMI, care must be
taken during printed circuit board layout. Figure 8 shows
the recommended component placement with trace,
ground plane and via locations. Note that large, switched
TheLT8697withstandsashortbetweenitsoutputand12V
or 24V automotive battery voltage. The USB5V pin draws
ꢁigure 8. Recommended PCB Layout for the Lꢂ8697
8697p
22
For more information www.linear.com/LT8697
LINEAR_DIMENSIONS [ Linear Dimensions ]
