Datasheet

LTC3728
4
3728fg
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS1, 2
= 5V unless otherwise noted.
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: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3728: T
J
= T
A
+ (P
D
• 95 °C/W)
Note 3: The LTC3728 is tested in a feedback loop that servos V
ITH1, 2
to a
specifi ed voltage and measures the resultant V
OSENSE1, 2.
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive
l
4.5 4.7 V
V
LDOHYS
EXTV
CC
Hysteresis 0.2 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLFLTR
= 1.2V 360 400 440 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 230 260 290 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 480 550 590 kHz
R
PLLIN
PLLIN Input Resistance 50 k
I
PLLFLTR
Phase Detector Output Current
Sinking Capability
Sourcing Capability
f
PLLIN
< f
OSC
f
PLLIN
> f
OSC
–15
15
µA
µA
3.3V Linear Regulator
V
3.3OUT
3.3V Regulator Output Voltage No Load
l
3.25 3.35 3.45 V
V
3.3IL
3.3V Regulator Load Regulation I
3.3
= 0 to 10mA 0.5 2 %
V
3.3VL
3.3V Regulator Line Regulation 6V < V
IN
< 30V 0.05 0.2 %
I
3.3LEAK
Leakage Current of 3.3V Regulator in
Shutdown
V
RUN/SS1, 2
= 0V, V
IN
= 25V 10 50 µA
PGOOD Output
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 0.1 0.3 V
I
PGOOD
PGOOD Leakage Current V
PGOOD
= 5V ±1 µA
V
PG
PGOOD Trip Level, Either Controller V
OSENSE
with Respect to Set Output Voltage
V
OSENSE
Ramping Negative
V
OSENSE
Ramping Positive
–6
6
–7.5
7.5
–9.5
9.5
%
%
Note 5: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 6: The IC minimum on-time is tested under an ideal condition
without external power FETs. It can be different when the IC is working in
an actual circuit. See Minimum On-Time Considerations in the Application
Information section.
Note 7: The LTC3728E is guaranteed to meet performance specifi cations
from 0°C to 85°C. Specifi cations over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3728I is guaranteed to meet
performance specifi cations over the full –40°C to 85°C operating
temperature range.