LT3493-3 LINER [Linear Technology], LT3493-3 Datasheet - Page 17

• Manufacturer Part Number: LT3493-3
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
loss. The resulting temperature rise at full load is nearly
independent of input voltage. Thermal resistance de-
pends on the layout of the circuit board, but 64°C/W is
typical for the (2mm × 3mm) DFN (DCB) package.
Outputs Greater Than 6V
For outputs greater than 6V, add a resistor of 1k to 2.5k
across the inductor to damp the discontinuous ringing of
the SW node, preventing unintended SW current. The 12V
Step-Down Converter circuit in the Typical Applications
section shows the location of this resistor. Also note that
for outputs above 6V, the input voltage range will be
TYPICAL APPLICATIO S
U
U
6.8V TO 25V
6.8V TO 25V
ON OFF
ON OFF
U
W
V
V
IN
IN
2.2µF
2.2µF
V
SHDN
V
SHDN
IN
IN
0.78V Step-Down Converter
U
1.8V Step-Down Converter
LT3493-3
LT3493-3
1N4148
1N4148
GND
GND
BOOST
BOOST
SW
SW
FB
FB
limited by the maximum rating of the BOOST pin. The 12V
circuit shows how to overcome this limitation using an
additional zener diode.
Other Linear Technology Publications
Application notes AN19, AN35 and AN44 contain more
detailed descriptions and design information for Buck
regulators and other switching regulators. The LT1376
data sheet has a more extensive discussion of output
ripple, loop compensation and stability testing. Design
Note DN100 shows how to generate a bipolar output
supply using a Buck regulator.
0.1µF 5µH
0.1µF 3.3µH
MBRM140
MBRM140
26.1k
20k
3493-3 TA03
3493-3 TA02
22µF
47µF
V
1.8V
1.2A
V
0.78V
1.2A
OUT
OUT
LT3493-3
17
3493-3f