LTC3728_15 Datasheet, PDF (4/36 Pages) Linear Technology – Dual, 550kHz, 2-Phase Synchronous Step-Down Switching Regulator

LTC3728
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 15V, V_{RUN/SS1, 2} = 5V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
V_EXTVCC
EXTV_CC Switchover Voltage
V_LDOHYS
EXTV_CC Hysteresis
Oscillator and Phase-Locked Loop
I_CC = 20mA, EXTV_CC Ramping Positive
l 4.5
4.7
V
0.2
V
f_NOM
Nominal Frequency
f_LOW
Lowest Frequency
f_HIGH
Highest Frequency
R_PLLIN
PLLIN Input Resistance
I_PLLFLTR
Phase Detector Output Current
Sinking Capability
Sourcing Capability
3.3V Linear Regulator
V_PLLFLTR = 1.2V
V_PLLFLTR = 0V
V_PLLFLTR ≥ 2.4V
f_PLLIN < f_OSC
f_PLLIN > f_OSC
360
400 440 kHz
230
260 290 kHz
480
550 590 kHz
50
kΩ
–15
μA
15
μA
V_3.3OUT
3.3V Regulator Output Voltage
No Load
l 3.25 3.35 3.45
V
V_3.3IL
V_3.3VL
I_3.3LEAK
3.3V Regulator Load Regulation
3.3V Regulator Line Regulation
Leakage Current of 3.3V Regulator in
Shutdown
I_3.3 = 0 to 10mA
6V < V_IN < 30V
V_{RUN/SS1, 2} = 0V, V_IN = 25V
0.5 2
%
0.05 0.2
%
10 50
μA
PGOOD Output
V_PGL
I_PGOOD
V_PG
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level, Either Controller
I_PGOOD = 2mA
V_PGOOD = 5V
V_OSENSE with Respect to Set Output Voltage
V_OSENSE Ramping Negative
V_OSENSE Ramping Positive
0.1 0.3
V
±1
μA
–6
–7.5 –9.5
%
6
7.5 9.5 %
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
specified 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.
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 specifications
from 0°C to 85°C. Specifications 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 specifications over the full –40°C to 85°C operating
temperature range.
3728fg
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