Datasheet

LTC3108
18
3108fc
For more information www.linear.com/LTC3108
duration of the burst and T is the period of the transmit
burst rate (essentially the time between bursts).
In this example, I
Q
= 5µA, I
BURST
= 100mA, t = 5ms and
T = one hour. The average charge current required from
the LTC3108 would be:
≥+ =I5µA
100mA • 0.005sec
3600sec
5.14µA
CHG
Therefore, if the LTC3108 has an input voltage that allows
it to supply a charge current greater than 5.14µA, the
application can support 100mA bursts lasting 5ms every
hour. It can be determined that the sleep current of 5µA
is the dominant factor because the transmit duty cycle is
so small (0.00014%). Note that for a V
OUT
of 3.3V, the
average power required by this application is only 17µW
(not including converter losses).
Note that the charge current available from the LTC3108
has no effect on the sizing of the V
OUT
capacitor (if it is
assumed that the load current during a burst is much larger
than the charge current), and the V
OUT
capacitor has no
effect on the maximum allowed burst rate.
applicaTions inForMaTion
Peltier-Powered Energy Harvester for Remote Sensor Applications
Typical applicaTions
3108 TA02
C1
C2
SW
VS2
VS1
COOPER BUSSMAN PB-5ROH104-R
OR KR-5R5H104-R
V
OUT2
V
OUT2
PGOOD
2.2V
C
OUT
*
PGD
VLDO
VSTORE
+
V
OUT
V
OUT2_EN
LTC3108
VAUX GND
C
STORE
0.1F
6.3V
5V
3.3V
1µF
1nF
C
IN
1:100
T1
T1: COILCRAFT LPR6235-752SML
*C
OUT
VALUE DEPENDENT ON
THE MAGNITUDE AND DURATION
OF THE LOAD PULSE
330pF
∆T = 1°C TO 20°C
SENSORS
XMTR
µP
2.2µF
ON
OFF
3.3V
+
+
+
THERMOELECTRIC
GENERATOR