Datasheet

LTC3859AL
6
3859alf
For more information www.linear.com/3859AL
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 LTC3859AL is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3859ALE is guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3859ALI is guaranteed over the –40°C to 125°C operating junction
temperature range, the LTC3859ALH is guaranteed over the –40°C to
150°C operating junction temperature range and the LTC3859ALMP
is tested and guaranteed over the –55°C to 150°C operating junction
temperature range. High junction temperatures degrade operating
lifetimes; operating lifetime is derated for junction temperatures greater
than 125°C. 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. 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
• q
JA
), where q
JA
= 34.7°C/W for the QFN package and q
JA
= 25°C/W
for the TSSOP package.
Note 3: This IC includes overtermperature 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 LTC3859AL is tested in a feedback loop that servos V
ITH1,2,3
to a specified voltage and measures the resultant V
FB
. The specification at
85°C is not tested in production and is assured by design, characterization
and correlation to production testing at other temperatures (125°C for the
LTC3859ALE/LTC3859ALI, 150°C for the LTC3859ALH/LTC3859ALMP).
For the LTC3859ALI and LTC3859ALH, the specification at 0°C is not
tested in production and is assured by design, characterization and
correlation to production testing at –40°C. For the LTC3859ALMP, the
specification at 0°C is not tested in production and is assured by design,
characterization and correlation to production testing at –55°C.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching
frequency. See the Applications Information
section.
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 specified for an inductor
peak-to-peak ripple current ≥ 40% of I
MAX
(See the Minimum On-Time
Considerations in the Applications Information section).
elecTrical characTerisTics
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
T
PG1
Delay For Reporting a Fault 40 µs
OV3 Boost Overvoltage Indicator Output
V
OV3L
OV3 Voltage Low I
OV3
= 2mA 0.2 0.4 V
I
OV3
OV3 Leakage Current V
OV3
= 5V ±1 µA
V
OV
OV3 Trip Level V
FB3
Ramping Positive with Respect to Set
Regulated Voltage
6 10 13 %
Hysteresis 1.5 %
BOOST3 Charge Pump
I
BST3
BOOST3 Charge Pump Available Output
Current
V
BOOST3
= 16V; V
SW3
= 12V;
Forced Continuous Mode
65 µA
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
BIAS
= 12V, V
RUN1,2,3
= 5V, EXTV
CC
= 0V unless otherwise
noted. (Note 2)