Datasheet

LTC3786
4
3786fc
For more information www.linear.com/LTC3786
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 LTC3786 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3786E is guaranteed to meet specifications from
0°C to 85°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3786I is guaranteed over the –40°C to 125°C operating junction
temperature range. The LTC3786H is guaranteed over the –40°C to 150°C
operating temperature range. High temperatures degrade operating
lifetimes; operating lifetime is derated for junction temperatures greater
than 125ºC. Note that the maximum ambient temperature consistent
with these specifications is determined by specific operating conditions
in conjunction with board layout, the rated package thermal impedance
and other environmental factors. The junction temperature (T
J
in °C) is
calculated from the ambient temperature (T
A
in °C) and power dissipation
(P
D
in Watts) according to the formula:
T
J
= T
A
+ (P
D
• θ
JA
)
The
l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
BIAS
= 12V, unless otherwise noted (Note 2).
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
INTV
CC
Linear Regulator
V
INTVCC(VIN)
Internal V
CC
Voltage 6V < VBIAS < 38V 5.2 5.4 5.6 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0mA to 50mA 0.5 2 %
Oscillator and Phase-Locked Loop
f
PROG
Programmable Frequency R
FREQ
= 25k
R
FREQ
= 60k
R
FREQ
= 100k
335
105
400
760
465
kHz
kHz
kHz
f
LOW
Lowest Fixed Frequency V
FREQ
= 0V 320 350 380 kHz
f
HIGH
Highest Fixed Frequency V
FREQ
= INTV
CC
485 535 585 kHz
f
SYNC
Synchronizable Frequency PLLIN/MODE = External Clock
l
75 850 kHz
PGOOD Output
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 0.2 0.4 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
Hysteresis
V
FB
Ramping Positive
Hysteresis
–12
8
–10
2.5
10
2.5
–8
12
%
%
%
%
t
PGOOD(DELAY)
PGOOD Delay PGOOD Going High to Low 25 µs
BOOST Charge Pump
I
BOOST
BOOST Charge Pump Available
Output Current
V
SW
= 12V; V
BOOST
– V
SW
= 4.5V;
FREQ = 0V, Forced Continuous or
Pulse-Skipping Mode
85 µA
where θ
JA
= 68°C for the QFN package and θ
JA
= 40°C for the MSOP
package.
Note 3: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4: The LTC3786 is tested in a feedback loop that servos V
FB
to the
output of the error amplifier while maintaining I
TH
at the midpoint of the
current limit range.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7: see Minimum On-Time Considerations in the Applications
Information section.
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