LTC3785 Datasheet, PDF (3/20 Pages) Linear Technology – 10V, High Effi ciency, Synchronous, No RSENSE Buck-Boost Controller

LTC3785
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = V_OUT = V_DRV = V_BST1 = V_BST2 = 3.6V, R_T = 49.9k, R_ILSET = 59k.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Undervoltage Threshold
V_SENSE Input Current
V_CC Regulator
V_CC Maximum Regulating Voltage
V_CC Regulation Voltage
V_CC Regulator Sink Current
Run/Soft-Start
V_SENSE Pin. % Below FB
V_SENSE = Measured FB Voltage
V_IN = 5V, I_VCC = –20mA
V_IN = 3.6V, I_VCC = –20mA
V_OUT = V_CC = 5V
● –3.5 –6.5 –9.5
%
1
500
nA
● 4.15 4.35 4.55
V
● 3.3
3.5
3.6
V
800
µA
RUN/SS Threshold
When IC is Enabled
When EA is at Maximum Boost Duty Cycle
● 0.35
0.7
1.1
V
1.9
V
RUN/SS Input Current
RUN/SS = 0V
–1
µA
RUN/SS Discharge Current
During Current Limit
1
5
µA
Current Limit
Current Limit Sense Threshold
Reverse Current Limit Sense Threshold
Input Current
CCM Input Threshold (High)
I_SVIN to I_SSW1, R_ILSET = 121k
I_SVIN to I_SSW1, R_ILSET = 59k
I_SSW2 to I_SVOUT, CCM > 2V
I_SSW2 to I_SVOUT, CCM < 0.4V
I_SVIN
I_SVOUT
I_SSW1, I_SSW2
● 20
60
100
mV
● 55
105
155
mV
● –50 –110 –170
mV
●
–15
–35
mV
80
150
µA
10
20
µA
0.1
5
µA
● 2.2
V
CCM Input Threshold (Low)
●
0.4
V
CCM Input Current
0.01
1
µA
Burst Mode Operation
Mode Threshold
● 0.8
1.5
2.2
V
Mode Input Current
0.01
1
µA
t_ON Time
Oscillator
1.4
µs
Frequency Accuracy
● 370
509
650
kHz
Switching Characteristics
Maximum Duty Cycle
Boost (% Switch BG2 On)
Buck (% Switch TG1 On)
● 80
90
%
99
%
TG1, TG2 Driver Impedance
2
Ω
BG1, BG2 Driver Impedance
2
Ω
TG1, TG2 Rise Time
BG1, BG2 Rise Time
TG1, TG2 Fall Time
BG1, BG2 Fall Time
Buck Driver Nonoverlap Time
C_LOAD = 3300pF (Note 3)
C_LOAD = 3300pF (Note 3)
C_LOAD = 3300pF (Note 3)
C_LOAD = 3300pF (Note 3)
TG1 to BG1
20
ns
20
ns
20
ns
20
ns
100
ns
Boost Driver Nonoverlap Time
TG2 to BG2
100
ns
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 LTC3785E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Specification is guaranteed by design and not 100% tested in production.
Note 4: Current measurements are performed when the outputs are not switching.
Note 5: The IC is tested in a feedback loop to make the measurement.
3785f
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