Datasheet

LTC3834
4
3834fb
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 12V, V
RUN
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
PGOOD Output
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 0.1 0.3 V
I
PGOOD
PGOOD Leakage Current V
PGOOD
= 5V
±1
μA
V
PG
PGOOD Trip Level V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
–12
8
–10
10
–8
12
%
%
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3834E is guaranteed to meet performance specifi cations
from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3834I is guaranteed to meet
performance specifi cations over the –40°C to 85°C operating temperature
range.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3834FE: T
J
= T
A
+ (P
D
• 35°C/W)
LTC3834UFD: T
J
= T
A
+ (P
D
• 37°C/W)
Note 4: The LTC3834 is tested in a feedback loop that servos V
ITH
to a
specifi ed voltage and measures the resultant V
FB
.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7: The minimum on-time condition is specifi ed for an inductor
peak-to-peak ripple current ≥40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information section).
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C, unless otherwise noted.
Effi ciency and Power Loss
vs Output Current
Effi ciency vs Load Current
OUTPUT CURRENT (A)
EFFICIENCY (%)
POWER LOSS (mW)
0.0001 0.01 1
3834 G01
0.000001
1
10
1000
100
0.1
10000
40
50
60
70
80
30
20
10
0
90
100
Burst Mode OPERATION
FORCED CONTINUOUS MODE
PULSE SKIPPING MODE
V
IN
= 12V
V
OUT
= 3.3V
FIGURE 11 CIRCUIT
Effi ciency vs Input Voltage
OUTPUT CURRENT (A)
EFFICIENCY (%)
0.0001 0.01 1
3834 G02
0.000001
40
50
60
70
80
90
100
V
IN
= 12V
V
IN
= 5V
FIGURE 11 CIRCUIT
V
OUT
= 3.3V
INPUT VOLTAGE (V)
88
90
94
96
98
515
3834 G03
86
84
0
10 20 4025 30 35
82
80
92
EFFICIENCY (%)
V
OUT
= 3.3V
FIGURE 11 CIRCUIT