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LTC3785_15 Datasheet, PDF (3/20 Pages) Linear Technology – 10V, High Efficiency, Synchronous, No RSENSE Buck-Boost Controller
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LTC3785
Electrical Characteristics The l denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at TA = 25°C. VIN = ISVOUT = VDRV = VBST1 = VBST2 = 3.6V, RT = 49.9k, RILSET = 59k.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Error Amp Source Current
–500
µA
Error Amp Sink Current
900
µA
Error Amp AVOL
90
dB
Overvoltage Threshold
VSENSE Pin % Above FB
LTC3785E
LTC3785I
l
6
10
14
%
l
6
10
15
%
Undervoltage Threshold
VSENSE Pin % Below FB
LTC3785E
LTC3785I
l –3.5 –6.5 –9.5
%
l –3.5 –6.5 –10.5
%
VSENSE Input Current
VSENSE = Measured FB Voltage
1
500
nA
VCC Regulator
VCC Maximum Regulating Voltage
VCC Regulation Voltage
VCC Regulator Sink Current
VIN = 5V, IVCC = –20mA
VIN = 3.6V, IVCC = –20mA
ISVOUT = VCC = 5V
l 4.15 4.35 4.55
V
l 3.3
3.5
3.6
V
800
µA
Run/Soft-Start
RUN/SS Threshold
When IC is Enabled
l 0.35
0.7
1.1
V
When EA is at Maximum Boost Duty Cycle
1.9
V
RUN/SS Input Current
RUN/SS = 0V
–1
µA
RUN/SS Discharge Current
During Current Limit
20
30
µA
Current Limit
Current Limit Sense Threshold
Reverse Current Limit Sense Threshold
Input Current
CCM Input Threshold (High)
ISVIN to ISSW1, RILSET = 121k
ISVIN to ISSW1, RILSET = 59k
ISSW2 to ISVOUT, CCM > 2V
ISSW2 to ISVOUT, CCM < 0.4V, LTC3785E
ISSW2 to ISVOUT, CCM < 0.4V, LTC3785I
ISVIN
ISVOUT
ISSW1, ISSW2
l 20
60
100
mV
l 55
105
155
mV
–50 –110 –170
mV
l
–15
–35
mV
l
–15
–40
mV
80
150
µA
10
20
µA
0.1
5
µA
l 2.2
V
CCM Input Threshold (Low)
l
0.4
V
CCM Input Current
CCM = 3.6V
0.01
1
µA
Burst Mode Operation
Mode Threshold
l 0.8
1.5
2.2
V
Mode Input Current
0.01
1
µA
tON Time
Oscillator
1.4
µs
Frequency Accuracy
l 370
509
650
kHz
Switching Characteristics
Maximum Duty Cycle
Boost (% Switch BG2 On)
Buck (% Switch TG1 On)
l 80
90
%
99
%
TG1, TG2 Driver Impedance
2
Ω
BG1, BG2 Driver Impedance
2
Ω
TG1, TG2 Rise Time
CLOAD = 3300pF (Note 3)
20
ns
3785fc

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