Datasheet

LTC3736-2
4
37362fb
LOAD CURRENT (mA)
65
EFFICIENCY (%)
POWER LOSS (W)
95
100
60
55
90
75
85
80
70
1 100 1000 10000
37362 G01
50
10
0.01
0.1
1
0.001
10
V
OUT
= 2.5V
EFFICIENCY
POWER LOSS
V
IN
= 3.3V
V
IN
= 5V
V
OUT
AC
COUPLED
100mV/
DIV
V
IN
= 3.3V
V
OUT
= 1.8V
I
LOAD
= 300mA TO 3A
SYNC/FCB = 0V
FIGURE 15 CIRCUIT
100μs/DIV
37362 G02
I
L
2A/DIV
TYPICAL PERFORMANCE CHARACTERISTICS
Effi ciency and Power Loss
vs Load Current
Load Step
(Forced Continuous Mode) Load Step (Pulse-Skipping Mode)
Light Load
(Pulse-Skipping Mode)
Light Load
(Forced Continuous Mode)
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 LTC3736E-2 is guaranteed to meet specifi ed performance
from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating 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 formula:
T
J
= T
A
+ (P
D
• θ
JA
°C/W)
ELECTRICAL CHARACTERISTICS
Note 4: Dynamic supply current is higher due to gate charge being
delivered at the switching frequency.
Note 5: The LTC3736-2 is tested in a feedback loop that servos I
TH
to a
specifi ed voltage and measures the resultant V
FB
voltage.
Note 6: Peak current sense voltage is reduced dependent on duty cycle to
a percentage of value as shown in Figure 1.
V
OUT
AC
COUPLED
100mV/
DIV
V
IN
= 3.3V
V
OUT
= 1.8V
I
LOAD
= 300mA TO 3A
SYNC/FCB = V
IN
FIGURE 15 CIRCUIT
100μs/DIV
37362 G03
I
L
2A/DIV
SW
5V/DIV
V
OUT
50mV/DIV
AC
COUPLED
2.5μs/DIVV
IN
= 5V
V
OUT
= 2.5V
I
LOAD
= 300mA
SYNC/FBC = V
IN
FIGURE 15 CIRCUIT
37362 G04
I
L
2A/DIV
SW
5V/DIV
V
OUT
50mV/DIV
AC COUPLED
2.5μs/DIV
37362 G05
I
L
2A/DIV
V
IN
= 5V
V
OUT
= 2.5V
I
LOAD
= 300mA
SYNC/FCB = 0V
FIGURE 15 CIRCUIT
V
IN
= 5V
R
LOAD1
= R
LOAD2
= 1Ω
FIGURE 15 CIRCUIT
200μs/DIV
37362 G06
500mV/
DIV
V
OUT1
2.5V
V
OUT2
1.8V
T
A
= 25°C, unless otherwise noted.
Tracking Start-Up with Internal
Soft-Start (C
SS
= 0μF)