LTC3787IUFD 查看數據表（PDF） - Linear Technology
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LTC3787IUFD Datasheet PDF : 36 Pages
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LTC3787
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C, VBIAS = 12V, unless otherwise noted (Note 2).
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
INTVCC Linear Regulator
VINTVCC(VIN)
VLDO INT
VINTVCC(EXT)
VLDO EXT
VEXTVCC
Internal VCC Voltage
INTVCC Load Regulation
Internal VCC Voltage
INTVCC Load Regulation
EXTVCC Switchover Voltage
6V < VBIAS < 38V, VEXTVCC = 0
5.2
5.4
5.6
V
ICC = 0mA to 50mA
0.5
2
%
VEXTVCC = 6V
5.2
5.4
5.6
V
ICC = 0mA to 40mA, VEXTVCC = 6V
0.5
2
%
EXTVCC Ramping Positive
l 4.5
4.8
5
V
VLDOHYS
EXTVCC Hysteresis
Oscillator and Phase-Locked Loop
250
mV
fPROG
fLOW
fHIGH
fSYNC
Programmable Frequency
Lowest Fixed Frequency
Highest Fixed Frequency
Synchronizable Frequency
RFREQ = 25k
RFREQ = 60k
RFREQ = 100k
VFREQ = 0V
VFREQ = INTVCC
PLLIN/MODE = External Clock
105
kHz
335
400
465
kHz
760
kHz
320
350
380
kHz
488
535
585
kHz
l 75
850
kHz
PGOOD Output
VPGL
IPGOOD
VPGOOD
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
IPGOOD = 2mA
0.2
0.4
V
VPGOOD = 5V
±1
μA
VFB with Respect to Set Regulated Voltage
VFB Ramping Negative
Hysteresis
–12 –10
–8
%
2.5
%
VFB Ramping Positive
Hysteresis
8
10
12
%
2.5
%
tPGOOD(DELAY) PGOOD Delay
BOOST1 and BOOST2 Charge Pump
PGOOD Going High to Low
25
μs
IBOOST1,2
BOOST Charge Pump Available Output
Current
VSW1,2 = 12V; VBOOST1,2 – VSW1,2 = 4.5V;
FREQ = 0V, Forced Continuous or
Pulse-Skipping Mode
55
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: The LTC3787 is tested under pulsed load conditions such that
TJ ≈ TA. The LTC3787E 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
LTC3787I is guaranteed over the –40°C to 125°C operating junction
temperature range, the LTC3787H is guaranteed over the –40°C to 150°C
operating temperature range and the LTC3787MP is tested and guaranteed
over the full –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. The junction temperature (TJ, in °C) is calculated from the ambient
temperature (TA, in °C) and power dissipation (PD, in Watts) according to
the formula: TJ = TA + (PD • θJA), where θJA = 43°C/W for the QFN package
and θJA = 90°C/W for the SSOP package.
Note 3: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4: The LTC3787 is tested in a feedback loop that servos VFB to the
output of the error amplifier while maintaining ITH at the midpoint of the
current limit range.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7: see Minimum On-Time Considerations in the Applications
Information section.
3787fc
4
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