Datasheet
3
LTC1878
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC1878E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC1878EMS8: T
J
= T
A
+ (P
D
)(150°C/W)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
PK
Peak Inductor Current V
IN
= 3.3V, V
FB
= 0.7V, Duty Cycle < 35% 0.8 1.0 1.25 A
I
LSW
SW Leakage V
RUN
= 0V, V
SW
= 0V or 6V, V
IN
= 6V ±0.01 ±1 µA
V
SYNC/MODE
SYNC/MODE Threshold V
SYNC/MODE
Rising ● 0.3 1.0 1.5 V
I
SYNC/MODE
SYNC/MODE Leakage Current ±0.01 ±1 µA
V
RUN
RUN Threshold V
RUN
Rising ● 0.3 0.7 1.5 V
I
RUN
RUN Input Current ±0.01 ±1 µA
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
IN
= 3.6V unless otherwise specified.
Note 4: The LTC1878 is tested in a feedback loop which servos V
FB
to the
balance point for the error amplifier (V
ITH
= 1.2V).
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
ELECTRICAL CHARACTERISTICS
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Efficiency vs Input Voltage
INPUT VOLTAGE (V)
2
EFFICIENCY (%)
75
80
85
5
7
1878 G01
70
65
60
34 6
90
95
100
8
Burst Mode OPERATION
V
OUT
= 2.5V
L = 10µH
I
LOAD
= 100mA
I
LOAD
= 10mA
I
LOAD
= 1mA
I
LOAD
= 300mA
I
LOAD
= 0.1mA
OUTPUT CURRENT (mA)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.1 10 100 1000
1878 G02
0
1
V
IN
= 3.6V
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 4.2V
PULSE SKIPPING MODE
Burst Mode OPERATION
V
OUT
= 1.8V
L = 10µH
OUTPUT CURRENT (mA)
60
EFFICIENCY (%)
70
75
85
95
0.1 10 100 1000
1878 G03
50
1
80
65
55
90
L = 15µH
L = 10µH
Burst Mode OPERATION
V
IN
= 6V
V
OUT
= 2.5V
Efficiency vs Output Current Efficiency vs Output Current