LT3781 Ver la hoja de datos (PDF) - Linear Technology
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LT3781 Datasheet PDF : 20 Pages
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LT3781
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
VCC = VBST = 12V, VBSTREF = 0V, VVC = 2V, VTS = 0V, VFB = VREF = 1.25V, CTG = CBG = CSG = 1000pF.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
Error Amp
VFB
Error Amplifier Reference Voltage
Measured at Feedback Pin
1.242 1.250 1.258
q 1.225
1.265
IFB
Feedback Input Current
AV
Error Amplifier Voltage Gain
IVC
Error Amplifier Current Limit
VFB = VREF
Source
Sink
– 50
72
q
10
25
q
0.5
1
VVC
Zero Current Output Voltage
1.4
Maximum Output Voltage
3.2
GBW Gain Bandwidth Product
(Note 3)
1
Current Sense
AV
ISENSE
VSENSE
Amplifier DC Gain
Input Bias Current
Current Limit Threshold
Measured at SENSE Pin
12
– 275
135 150 165
q
130
170
tD
Current Sense to Switch Delay
175
tMIN
Switch Minimum On Time
Measured at BG Output
250
THERM and OVLO Fault Detectors
VTHERM/ Threshold (Rising Edge)
VOVLO Threshold Hysteresis
tD
Fault Delay to Output Disable
Oscillator and Synchronization Decoder
>50mV Overdrive
q
1.2
1.25
1.3
q
20
40
60
650
fOSC
IFSET
VSYNC
Oscillator Frequency, Free Run
Frequency Programming Error
FSET Input Bias Current
SYNC Logic High Input Threshold
SYNC Logic Low Input Threshold
Measured at FSET Pin
fOSC ≤ 500kHz (Note 3)
FSET Charging, VFSET = 2V
Positive-Going Edge
Negative-Going Edge
700
q
–10
5
50
q
1.4
2
q
0.8
1.4
fSYNC
tH, L
SYNC Frequency
Maximum SYNC Pulse Width
(Logic High or Logic Low)
fOSC = Oscillator Free-Run Frequency
q
fOSC/2
350
1/fOSC
Output Drivers
VTG
TG On Voltage
TG Off Voltage
q
11
11.5
q
0.1
0.5
tTGr/f
TG Rise/Fall Time
VBG
BG On Voltage
BG Off Voltage
10% to 90%/90% to 10%
35
q
11
11.5
12
q
0.1
0.5
tBGr/f
BG Rise/Fall Time
VSG
SG On Voltage
SG Off Voltage
10% to 90%/90% to 10%
35
q
11
11.5
12
q
0.1
0.5
tSGr/f
tSG-BG
tTG-BG
SG Rise/Fall Time
SG to BG Enable Lag Time
TG to BG Enable Lag Time
10% to 90%/90% to 10%
4V On/Off Thresholds
4V On/Off Thresholds
35
q
80
150 300
100
UNITS
V
V
nA
dB
mA
mA
V
V
MHz
V/V
µA
mV
mV
ns
ns
V
mV
ns
kHz
%
nA
V
V
kHz
s
V
V
ns
V
V
ns
V
V
ns
ns
ns
3781f
3
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