Datasheet

LTC3105
12
3105fa
TEMPERATURE (°C)
–45
MPPC VOLTAGE (V)
0.4
–15 15 45
0.2
0.3
0.7
0.1
0
0.6
0.5
–30 0 75 9030 60
3105 TA02a
25µs/DIV
3105 TA02b
INPUT CURRENT
25mA/DIV
OUTPUT CURRENT
5mA/DIV
INPUT VOLTAGE
50mV/DIV
V
OUT
= 2.8V
V
MPPC
= 0.4V
V
FB
= 0.94V
0.38V
10mA
0.7mA
APPLICATIONS INFORMATION
Industrial Current Loops
The low 250mV start-up and low voltage operation of the
LTC3105 allow it to be supplied by power from a diode
placed in an industrial sensor current loop, as shown
in Figure 6. In this application, a large input capacitor
is required due to the very low available supply current
(less than 4mA). The loop diode should be selected for a
minimum forward drop of 300mV. The MPPC pin voltage
should be set for a value approximately 50mV below the
minimum diode forward voltage.
Figure 6. Current Loop Power Tap
3105 F06
GND
MPPC
V
IN
LTC3105
C
IN
V
FWD
R
MPPC
4mA TO 20mA
CURRENT LOOP
+
–
3.3V from a Single-Cell Photovoltaic Source with Temperature Tracking
V
MPPC
vs Temperature MPPC Response to Input Source Current Step
3105 TA02
C
OUT
10µF
R1
2.26M
V
OUT
3.3V
R2
1M
FB
PGOOD
LDO
FBLDO
MPPC
SHDN
AUX
SW
C
LDO
4.7µF
2.2V
R
MPPC
9.09k
C
AUX
1µF
* MRA4003T3
** COILCRAFT MSS5131-103MX
LTC3105
C
MPPC
10nF
GND
C
IN
10µF
L1**
10µH
+
–
ON
OFF
V
IN
V
OUT
D1*
THERMALLY
COUPLED
TYPICAL APPLICATIONS