Datasheet

LTC3858-1
4
38581fd
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
= 12V, V
RUN1,2
= 5V, EXTV
CC
= 0V unless
otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
BG1,2 t
r
BG1,2 t
f
BG Transistion Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
28
13
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
1D
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) 95 ns
INTV
CC
Linear Regulator
V
INTVCCVIN
Internal V
CC
Voltage 6V < V
IN
< 38V, V
EXTVCC
= 0V 4.85 5.1 5.35 V
V
LDOVIN
INTV
CC
Load Regulation I
CC
= 0mA to 50mA, V
EXTVCC
= 0V 0.7 1.1 %
V
INTVCCEXT
Internal V
CC
Voltage 6V < V
EXTVCC
< 13V 4.85 5.1 5.35 V
V
LDOEXT
INTV
CC
Load Regulation I
CC
= 0mA to 50mA, V
EXTVCC
= 8.5V 0.6 1.1 %
V
EXTVCC
EXTV
CC
Switchover Voltage EXTV
CC
Ramping Positive 4.5 4.7 4.9 V
V
LDOHYS
EXTV
CC
Hysteresis Voltage 250 mV
Oscillator and Phase-Locked Loop
f
25k
Programmable Frequency R
FREQ
= 25k, PLLIN/MODE = DC Voltage 105 kHz
f
65k
Programmable Frequency R
FREQ
= 65k, PLLIN/MODE = DC Voltage 375 440 505 kHz
f
105k
Programmable Frequency R
FREQ
= 105k, PLLIN/MODE = DC Voltage 835 kHz
f
LOW
Low Fixed Frequency V
FREQ
= 0V, PLLIN/MODE = DC Voltage 320 350 380 kHz
f
HIGH
High Fixed Frequency V
FREQ
= INTV
CC
, PLLIN/MODE = DC Voltage 485 535 585 kHz
f
SYNC
Synchronizable Frequency PLLIN/MODE = External Clock
l
75 850 kHz
PGOOD1 Output
V
PGL
PGOOD1 Voltage Low I
PGOOD
= 2mA 0.2 0.4 V
I
PGOOD
PGOOD1 Leakage Current V
PGOOD
= 5V ±1 µA
V
PG
PGOOD1 Trip Level V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
Hysteresis
–13 –10
2.5
–7 %
%
V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Positive
Hysteresis
710
2.5
13 %
%
t
PG
Delay for Reporting a Fault (PGOOD Low) 25 µs
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Ratings for extended periods may affect device reliability and
lifetime.
Note 2: The LTC3858-1 is tested under pulsed conditions such that
T
J
≈ T
A
. The LTC3858E-1 is guaranteed to meet performance specifi cations
from 0°C to 85°C. 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 LTC3858I-1 is guaranteed
over the full –40°C to 125°C operating junction temperature range.
Note that the maximum ambient temperature 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 formula:
T
J
= T
A
+ (P
D
• θ
JA
)
where θ
JA
= 43°C/W for the QFN package and θ
JA
= 90°C/W for the SSOP
package.
Note 4: The LTC3858-1 is tested in a feedback loop that servos V
ITH1,2
to
a specifi ed voltage and measures the resultant V
FB1,2
. 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: The minimum on-time condition is specifi ed for an inductor peak-
to-peak ripple current ≥ of I
MAX
(See Minimum On-Time Considerations in
the Applications Information section).