ltc3108-1 Linear Technology Corporation, ltc3108-1 Datasheet - Page 18

• Manufacturer Part Number: ltc3108-1
• Description: Ltc3108-1 Ultralow Voltage Step-up Converter And Power Manager Features
• Manufacturer: Linear Technology Corporation

LTC3108-1
applicaTions inForMaTion
If there were 50µA of charge current available and 5µA of
load on V
the initial application of power would be 11.35 seconds.
Design Example 2
In many pulsed load applications, the duration, magnitude
and frequency of the load current bursts are known and
fixed. In these cases, the average charge current required
from the LTC3108-1 to support the average load must be
calculated, which can be easily done by the following:
Where I
ternal circuitry in between bursts (including cap leakage),
I
duration of the burst and T is the period of the transmit
burst rate (essentially the time between bursts).
Typical applicaTions

BURST
I
CHG
is the total load current during the burst, t is the
Q
≥
OUT
THERMOELECTRIC
GENERATOR
is the sleep current on V
I
Q
, the time for V
+
I
BURST
∆T = 1°C TO 20°C
T
•
T1: COILCRAFT LPR6235-752SML
*C
t
THE MAGNITUDE AND DURATION
OF THE LOAD PULSE
+
OUT
OUT
VALUE DEPENDENT ON
+
Peltier-Powered Energy Harvester for Remote Sensor Applications
to reach regulation after
C
OUT
IN
1:100
required by the ex-
T1
330pF
499k
1nF
C1
C2
SW
VS2
VS1
VAUX
LTC3108-1
In this example, I
T = one hour. The average charge current required from
the LTC3108-1 would be:
Therefore, if the LTC3108-1 has an input voltage that al-
lows 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
power required by this application is only 15.4µW (not
including converter losses).
Note that the charge current available from the LTC3108-1
has no effect on the sizing of the V
assumed that the load current during a burst is much larger
than the charge current), and the V
effect on the maximum allowed burst rate.
1µF
I
CHG
V
GND
VSTORE
OUT2_EN
V
VLDO
V
OUT2
PGD
OUT
≥
5
µA
3V
OFF
5.25V
2.2V
+
+
PGOOD
ON
100
Q
+
C
= 5µA, I
OUT
COOPER BUSSMAN PB-5ROH104-R
2.2µF
C
0.1F
6.3V
mA
*
STORE
3600
• .
V
BURST
OUT2
µP
0 005
sec
OR KR-5R5H104-R
= 100mA, t = 5ms and
SENSORS
sec
OUT
XMTR
OUT
OUT
31081 TA02
of 3V, the average
=
capacitor has no
capacitor (if it is
3V
5 14
.
µA
31081f