LTC3109
ELECTRICAL CHARACTERISTICS
board layout, the rated thermal package thermal resistance and other
environmental factors. The junction temperature (T
J
) is calculated from
the ambient temperature (T
A
) and power dissipation (P
D
) according to
the formula: T
J
= T
A
+ (P
D
•
θ
JA
°C/W), where
θ
JA
is the package thermal
impedance.
Note 3:
Specification is guaranteed by design and not 100% tested in
production.
Note 4:
Current measurements are made when the output is not switching.
Note 5:
Failure to solder the exposed backside of the QFN package to the
PC board ground plane will result in a thermal resistance much higher
than 37°C/W.
Note 6:
The Absolute Maximum Rating is a DC rating. Under certain
conditions in the applications shown, the peak AC voltage on the C2A and
C2B pins may exceed ±8V. This behavior is normal and acceptable because
the current into the pin is limited by the impedance of the coupling
capacitor.
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C, unless otherwise noted.
I
IN
vs V
IN
1000
V
OUT
= 0V
10000
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
V
OUT
= 3.3V
NO LOAD ON VLDO
P
VOUT
(mW)
I
VOUT
vs V
IN
100
P
VOUT
vs V
IN
1:50 RATIO
C1 = 4.7nF
V
OUT
= 5V
100
I
IN
(mA)
1000
I
VOUT
(μA)
10
V
OUT
= 3.3V
1
10
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
1
10
100
V
IN
(mV)
1000
3109 G01
100
10
10
100
V
IN
(mV)
1000
3109 G02
0.1
10
100
V
IN
(mV)
1000
3109 G18
Input Resistance vs V
IN
7.0
6.5
6.0
EFFICIENCY (%)
5.5
R
IN
(Ω)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
10
100
V
IN
(mV)
1000
3109 G03
Efficiency vs V
IN
50
45
40
35
30
25
20
15
V
STARTUP
(OPEN CIRCUIT) (mV)
1000
3109 G04
Open-Circuit Start-Up Voltage
vs Source Resistance
90
80
70
60
50
40
30
20
10
0
V
OUT
= 0V
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
V
OUT
= 0V
1:100 RATIO, C1 = 1nF
1:50 RATIO, C1 = 4.7nF
1:20 RATIO, C1 = 10nF
10
5
0
10
100
V
IN
(mV)
0
1
2 3 4 5 6 7 8
SOURCE RESISTANCE (Ω)
9
10
3109 G05
3109fa
4
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
