LTC3634
4
3634fc
For more information www.linear.com/LTC3034
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the specified operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 4). V
IN
= 12V, INTV
CC
= 3.3V, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch Leakage Current V
IN
= 15V, V
RUN
= 0V 0.01 ±1 µA
V
IN
Overvoltage Lockout Threshold V
IN
Rising
V
IN
Falling
16.8
15.8
17.5
16.5
18
17
V
V
INTV
CC
Voltage 3.6V < V
IN
< 15V, 0mA Load 3.1 3.3 3.5 V
INTV
CC
Load Regulation 0mA to 50mA Load, V
IN
= 4V to 15V 0.7 %
RUN Threshold Rising
RUN Threshold Falling
l
l
1.18
0.98
1.22
1.01
1.26
1.04
V
V
RUN Leakage Current 0 ±1 µA
PGOOD Good-to-Bad Threshold V
FB
Rising
V
FB
Falling
8
–8
10
–10
%
%
PGOOD Hysteresis V
FB
from Bad-to-Good 15 mV
R
PGOOD
PGOOD Pull-Down Resistance 10mA Load 15 Ω
Power Good Filter Time 20 40 µs
t
SS1
Channel 1 Internal Soft-Start Ramp Rate 0.7 1.2 V/ms
t
SS2
Channel 2 Internal Soft-Start Ramp Rate 1.5 2.2 V/ms
V
FB1
During Tracking TRACKSS = 0.3V 0.28 0.3 0.315 V
I
TRACKSS
TRACKSS Pull-Up Current 1.4 µA
Phase Shift Between Channel 1 and
Channel 2
PHMODE = 0V
PHMODE = INTV
CC
90
180
deg
deg
PHMODE Threshold Voltage V
IH
V
IL
1
0.3
V
V
MODE/SYNC Threshold Voltage V
IH
V
IL
1
0.4
V
V
SYNC Threshold Voltage V
IH
0.95 V
MODE/SYNC Input Current MODE = 0V
MODE = INTV
CC
1.5
–1.5
µA
µA
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: Transient event duration must be < 1% of total lifetime of the part.
Note 3: Guaranteed by long term current density limitations.
Note 4: The LTC3634 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3634E is guaranteed to meet specified performance
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
LTC3634I is guaranteed to meet specifications over the –40°C to 125°C
operating junction temperature range. The LTC3634H is guaranteed
over the –40°C to 150°C operating junction temperature range and the
LTC3634MP 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.
Note 5: The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C), package thermal impedance (θ
JA
, in °C/W), and
power dissipation (P
D
, in Watts) according to the formula: T
J
= T
A
+ P
D
• θ
JA
.
Note 6: Output voltage settings above 3V are not optimized for controlled
on-time operation. For designs that set output voltages above 3V, please
refer to the Applications Information section for information on device
operation outside the optimized range.
Note 7: Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 8: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
