Datasheet

LTC3865/LTC3865-1
5
3865fb
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 LTC3865/LTC3865-1 are tested under pulsed load conditions
such that T
J
≈ T
A
. The LTC3865E/LTC3865E-1 are guaranteed to meet
performance specifi cations over the 0°C to 85°C operating junction
temperature range. 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 LTC3865I/LTC3865I-1
are guaranteed to meet performance specifi cations 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 resistance and other environmental factors.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3865UH: T
J
= T
A
+ (P
D
• 34°C/W)
LTC3865FE: T
J
= T
A
+ (P
D
• 25°C/W)
Note 4: The LTC3865/LTC3865-1 are tested in a feedback loop that servos
V
ITH1,2
to a specifi ed voltage and measures the resultant V
OSENSE1,2
.
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).
Note 8: V
SENSE(MAX)
defaults to 50mV for the LTC3865-1.
Note 9: Guaranteed by design.
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
junction temperature range, otherwise specifi cations are at T
A
= 25°C (Note 2). V
IN
= 15V, V
RUN1,2
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
BG R
DOWN
BG Driver Pull-Down On-Resistance BG Low 1.4 
TG1,2 t
r
TG1,2 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
25
ns
ns
BG1,2 t
r
BG1,2 t
f
BG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
25
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 30 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 30 ns
t
ON(MIN)
Minimum On-Time (Note 7) 90 ns
INTV
CC
Linear Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
IN
< 38V 4.8 5.0 5.2 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0mA to 20mA 0.5 2 %
V
EXTVCC
EXTV
CC
Switchover Voltage EXTV
CC
Ramping Positive
l
4.5 4.7 V
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 5V 50 100 mV
V
LDOHYS
EXTV
CC
Hysteresis 200 mV
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency R
FREQ
= 162k 450 500 550 kHz
f
LOW
Lowest Frequency R
FREQ
= 0 210 250 290 kHz
f
HIGH
Highest Frequency R
FREQ
≥ 325k 650 770 880 kHz
R
MODE/PLLIN
MODE/PLLIN Input Resistance 250 kΩ
I
FREQ
Frequency Setting Current V
FREQ
= 1.22V 6.5 7.5 8.5 µA
PGOOD OUTPUT
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 0.1 0.3 V
I
PGOOD
PGOOD Leakage Current V
PGOOD
= 5V ±2 µA
V
PG
PGOOD Trip Level V
OSENSE
with Respect to Set Regulated Voltage
VID11 = VID12 = VID21 = VID22 = Float
V
OSENSE
Ramping Negative
V
OSENSE
Ramping Postitive
–7
7
–10
10
–12.5
12.5
%
%
t
PG
PGOOD Bad Blanking Time Measured from VID Transitition Edge 100 µs