Datasheet

LTC3827-1
4
38271fe
ELECTRICAL CHARACTERISTICS
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 LTC3827E-1 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 LTC3827I-1 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 formula:
T
J
= T
A
+ (P
D
• 95 °C/W)
Note 4: The LTC3827-1 is tested in a feedback loop that servos V
ITH1, 2
to
a specifi ed voltage and measures the resultant V
FB1, 2.
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
Effi ciency and Power Loss
vs Output Current Effi ciency vs Load Current Effi ciency vs Input Voltage
LOAD CURRENT (mA)
EFFICIENCY (%)
POWER LOSS (mW)
0.01 0.1 1 10 100 1000 10000
38271 G01
0.001
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
LOAD CURRENT (mA)
EFFICIENCY (%)
0.01 0.1 1 10 100 1000 10000
38271 G02
0.001
50
60
70
80
40
90
100
V
IN
= 12V
V
IN
= 5V
V
OUT
= 3.3V
INPUT VOLTAGE (V)
EFFICIENCY (%)
5101520 30 40
38271 G03
0
25 35
86
88
90
92
94
84
82
96
98
V
OUT
= 3.3V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
f
LOW
Lowest Frequency V
PLLLPF
= 0V; PLLIN/MODE = DC Voltage 220 250 280 kHz
f
HIGH
Highest Frequency V
PLLLPF
= INTV
CC
; PLLIN/MODE = DC Voltage 475 530 580 kHz
f
SYNCMIN
Minimum Synchronizable Frequency PLLIN/MODE = External Clock; V
PLLLPF
= 0V 115 140 kHz
f
SYNCMAX
Maximum Synchronizable Frequency PLLIN/MODE = External Clock; V
PLLLPF
= 2V 650 800 kHz
I
PLLLPF
Phase Detector Output Current
Sinking Capability
Sourcing Capability
f
PLLIN/MODE
< f
OSC
f
PLLIN/MODE
> f
OSC
–5
5
µA
µA
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
%
%
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/SS1, 2
= 5V unless otherwise noted.