LTC3621-2_15 Datasheet, PDF (4/18 Pages) Linear Technology – 17V, 1A Synchronous Step-Down Regulator with 3.5A Quiescent Current

LTC3621/LTC3621-2
Electrical Characteristics The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T_J = 25°C. (Note 3) V_IN = 12V, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX UNITS
V_MODE/SYNC Pulse-Skipping Mode
Burst Mode Operation
Forced Continuous Mode
I_MODE/SYNC
t_SS
I_LIM
MODE/SYNC Input Current
Internal Soft-Start Time
Peak Current Limit
(E/I-Grade)
(H-Grade)
V_INTVCC – 0.4
1.0
0.3
V
V
V_INTVCC – 1.2
V
0
20
nA
0.8
ms
1.44
1.60
1.76
A
l
1.30
1.80
A
l
1.2
1.80
A
V_UVLO
V_INTVCC Undervoltage Lockout
V_IN Ramping Up
2.4
2.6
2.7
V
V_UVLO(HYS) V_INTVCC Undervoltage Lockout Hysteresis
250
mV
V_OVLO
V_IN Overvoltage Lockout Rising
l
18
19
20
V
V_OVLO(HYS) V_IN Overvoltage Lockout Hysteresis
300
mV
f_OSC
Oscillator Frequency
LTC3621/LTC3621-3.3/LTC3621-5
0.92
1.00
1.08
MHz
(E/I-Grade)
l
0.82
1.16
MHz
(H-Grade)
l
0.78
1.16
MHz
LTC3621-2/LTC3621-23.3/LTC3621-25
2.05
2.25
2.45
MHz
(E/I-Grade)
l
1.8
2.6
MHz
(H-Grade)
l
1.7
2.6
MHz
f_SYNC
V_INTVCC
ΔV_PGOOD
R_PGOOD
t_PGOOD
SYNC Capture Range
V_INTVCC LDO Output Voltage
Power Good Range
Power Good Resistance
PGOOD Delay
V_IN > 4V
PGOOD R_DS(ON) at 500µA
PGOOD Low to High
PGOOD High to Low
60
140
%
3.6
V
±7.5
±12.5
%
275
350
Ω
0
Cycles
32
Cycles
I_PGOOD
PGOOD Leakage Current
100
nA
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 absolute maximum voltages should not be applied for
more than 4% of the switching duty cycle.
Note 3: The LTC3621 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3621E is guaranteed to meet specifications 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
LTC3621I is guaranteed over the –40°C to 125°C operating junction
temperature range, and the LTC3621H is guaranteed over the –40°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 4: The quiescent current in forced continuous mode does not include
switching loss of the power FETs.
Note 5: The LTC3621 is tested in a proprietary test mode that connects V_FB
to the output of error amplifier.
Note 6: T_J is calculated from the ambient, T_A, and power dissipation, P_D,
according to the following formula:
T_J = T_A + (P_D • θ_JA)
Note 7: 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.
3621fc
4
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