Datasheet

17
LTC1266
LTC1266-3.3/LTC1266-5
helpful in eliminating instabilities at high input voltage and
high output loads.
6. Is the shutdown (Pin 11) actively pulled to ground
during normal operation? The shutdown pin is high im-
pedance and must not be allowed to float. The select (Pins
3 and 4) are also high impedance and must be tied high or
low depending on the application.
3. Are the SENSE
–
and SENSE
+
leads routed together with
minimum PC trace spacing? The 1000pF capacitor be-
tween Pins 8 and 9 should be as close as possible to the
LTC1266.
4. Does the (+) plate of C
IN
connect to the source of the
topside MOSFET as closely as possible? This capacitor
provides the AC current to the topside MOSFET.
5. A 0.1µF to 1µF decoupling capacitor connected be-
tween V
IN
(Pin 5) and ground is optional, but is sometimes
(Layout Assist Schematics)
Figure 11. Low Dropout, 3.3V/3A High Efficiency Regulator
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
TDRIVE
PWR V
IN
PINV
BINH
V
IN
C
T
I
TH
SENSE
–
BDRIVE
PGND
LB
OUT
LB
IN
SGND
SHDN
NC
SENSE
+
LTC1266-3.3
1µF
1000pF
SHUTDOWN
BINH
R
SENSE
0.033Ω
L*
10µH
Si9410DY
D1
MBRS140T3
Si9430DY
+
C
IN
100µF
25V
V
IN
≈3.9V TO 18V
(V
IN(MIN)
= 3.5V IF I
LOAD
< 0.8A)
+
C
OUT
220µF
10V
2 ×
V
OUT
3.3V
3A
C
C
3300pF
R
C
1k
C
T
220pF
1266 F11
DALE LPT4545-A001
COILTRONICS CTX10-4
*
+
APPLICATIO S I FOR ATIO
WUUU
TYPICAL APPLICATIO S
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