Datasheet

LTC3859
6
3859fa
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 LTC3859 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3859E is guaranteed to meet specifi cations from
0°C to 85°C junction temperature. Specifi cations over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3859I is guaranteed over the full –40°C to 125°C operating junction
temperature range. Note that the maximum ambient temperature
consistent with these specifi cations is determined by specifi c 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
• q
JA
),
where q
JA
= 34°C/W for the QFN package and q
JA
= 25°C/W for the TSSOP
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 specifi ed absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4: The LTC3859 is tested in a feedback loop that servos V
ITH1,2,3
to a
specifi ed voltage and measures the resultant V
FB1,2,3
. The specifi cation at
85°C is not tested in production. This specifi cation is assured by design,
characterization and correlation to production testing at 125°C.
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: See Minimum On-Time Considerations in the Applications
Information section.
ELECTRICAL CHARACTERISTICS