LT3505
APPLICATIONS INFORMATION
I
LOAD
1A/DIV
V
OUT
22pF
32.4k
10.0k
FB
10µF
V
V
V
V
OUT
C
20mV/DIV
AC COUPLED
100k
22pF
3505 F05a
3505 F05b
3505 F05c
10µs/DIV
10µs/DIV
10µs/DIV
I
LOAD
1A/DIV
V
OUT
32.4k
44pF
10µF
×2
FB
C
V
OUT
10.0k
20mV/DIV
100k
AC COUPLED
22pF
I
LOAD
V
1A/DIV
OUT
32.4k
10.0k
66pF
+
FB
120µF
C
V
OUT
KEMET
A700D127M006ATE015
301k
20mV/DIV
AC COUPLED
22pF
Figure 5. Transient Load Response of the LT3505 with Different Output Capacitors as the
Load Current is Stepped from 500mA to 1.2A. VIN = 12V, VOUT = 3.3V, L = 2µH, RT = 20.0k
D2
D2
C3
C3
BOOST
LT3505
BOOST
LT3505
V
V
V
V
V
SW
V
SW
IN
OUT
IN
OUT
IN
IN
GND
GND
V
– V ≅ V
V
– V ≅ V
3505 F06a
BOOST
SW
OUT
BOOST
SW
IN
IN
3505 F06b
MAX V
≅ V + V
MAX V
≅ 2V
BOOST
BOOST
IN
OUT
(6a)
(6b)
Figure 6. Two Circuits for Generating the Boost Voltage
3505fc
15
Linear [ Linear ]
