LT1248 Ver la hoja de datos (PDF) - Linear Technology
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LT1248 Datasheet PDF : 12 Pages
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LT1248
ELECTRICAL CHARACTERISTICS The q denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. Maximum operating voltage (VMAX) = 25V, VCC = 18V, RSET = 15k to GND,
CSET = 1nF to GND, IAC = 100µA, ISENSE = 0V, CAOUT = 3.5V, VAOUT = 5V, OVP = 7.5V, no load on any outputs, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX
UNITS
Current Amplifier
Current Amp Short-Circuit Current
Input Range, ISENSE, MOUT (Linear Operation)
Reference
CAOUT = 0V
q
5
14
30
mA
q – 0.3
1
V
Reference Output Voltage
VREF Load Regulation
VREF Line Regulation
VREF Short-Circuit Current
VREF Worst Case
Current Limit
IREF = 0mA, TA = 25°C
– 5mA < IREF < 0mA
11.5V < VCC < VMAX
VREF = 0V
Load, Line, Temperature
7.39 7.50 7.60
V
5
mV
q – 20
5
20
mV
q
12
28
50
mA
q 7.32
7.5
7.68
V
PKLIM Offset Voltage
PKLIM Input Current
PKLIM to GTDR Propagation Delay
Multiplier
PKLIM = – 0.1V
PKLIM Falling from 50mV to – 50mV
q – 15
15
mV
q
– 50 – 100
µA
400
ns
Multiplier Output Current
Multiplier Output Current Offset
Multiplier Maximum Output Current
Multiplier Gain Constant (Note 2)
IAC = 100µA, RSET = 15k
35
µA
RAC = 1M from IAC to GND
q
– 0.05 – 0.5
µA
IAC = 450µA, RSET = 15k, VAOUT = 7V, MOUT = 0V q – 286 – 260 – 235
µA
0.035
V –2
IAC Input Resistance
Oscillator
IAC from 50µA to 1mA
15
32
50
kΩ
Oscillator Frequency
CSET Ramp Peak-to-Peak Amplitude
CSET Ramp Valley Voltage
Synchronization Pulse Threshold on EN/SYNC Pin
Synchronization Frequency Range
Overvoltage Comparator
RSET = 15k, CSET = 1000pF
RSET = 15k, CSET = 1500pF
Pulse Low = 3.5V, High = 7V, Width > 200ns
RSET = 15k, CSET = 1000pF
q
85
100 115
kHz
q
58
68
78
kHz
4.35
4.7
5.0
V
1.25
1.4
1.55
V
4.5
5.6
6.5
V
q 1.2
1.6
f NOM
Comparator Trip Voltage Ratio (VTRIP/ VREF)
Hysteresis
q 1.04 1.05 1.06
0.35
V
OVP Bias Current
OVP = 7.5V
q
– 50 – 250
nA
OVP Propagation Delay
100
ns
Gate Driver
Max GTDR Output Voltage
GTDR Output High
GTDR Output Low (Device Unpowered)
GTDR Output Low (Device Active)
0mA Load, 18V < VCC
– 200mA Load, 11.5V ≤ VCC ≤ 15V
VCC = 0V, 50mA Load (Sinking)
200mA Load (Sinking)
10mA Load
q
12
15
17.5
V
q VCC – 3.0
V
q
0.9
1.5
V
q
0.5
1
V
q
0.2
0.4
V
Peak GTDR Current
10nF from GTDR to GND
2
A
GTDR Rise and Fall Time
1nF from GTDR to GND
25
ns
GTDR Max Duty Cycle
90
96
%
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired
Note 2: Multiplier Gain Constant: K =
IM
IAC (VAOUT – 2)2
3
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