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LTC3805-5
3
38055fb
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 LTC3805E-5 is guaranteed to meet specications from
0°C to 85°C. Specications over the –40°C to 85°C operating junction
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3805I-5 is guaranteed over the
–40°C to 125°C operating junction temperature range and the LTC3805H-5
is guaranteed over the full –40°C to 150°C operating junction temperature
range. High junction temperatures degrade operating lifetimes. Operating
lifetime is derated at junction temperatures greater than 125°C.
Note 3: TJ is calculated from the ambient temperature TA and power
dissipation PD according to the following formula:
TJ = TA + (PD 45°C/W)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ICC
Input DC Supply Current
Normal Operation (fOSC = 200kHz)
(Note 4)
360
μA
VRUN < VRUNON or VCC < VTURNON – 100mV
(Micropower Start-Up)
l
40
90
μA
VRUNON
RUN Turn-On Voltage
VCC = VTURNON + 100mV
l
1.122
1.207
1.292
V
VRUNOFF
RUN Turn-Off Voltage
VCC = VTURNON + 100mV
l
1.092
1.170
1.248
V
IRUN(HYST)
RUN Hysteresis Current
l
4
5
5.8
μA
VFB
Regulated Feedback Voltage
0°C ≤ TA ≤ 85°C (E-Grade) (Note 5)
–40°C ≤ TA ≤ 85°C (E-Grade) (Note 5)
–40°C ≤ TA ≤ 125°C (I-Grade) (Note 5)
–40°C ≤ TA ≤ 150°C (H-Grade) (Note 5)
l
0.788
0.780
0.770
0.800
0.812
0.820
V
IFB
VFB Input Current
VITH = 1.3V (Note 5)
20
nA
gm
Error Amplier Transconductance
ITH Pin Load = ±5μA (Note 5)
333
μA/V
ΔVO(LINE)
Output Voltage Line Regulation
VTURNOFF < VCC < VCLAMP1mA (Note 5)
0.05
mV/V
ΔVO(LOAD)
Output Voltage Load Regulation
ITH Sinking 5μA (Note 5)
ITH Sourcing 5μA (Note 5)
3
mV/μA
fOSC
Oscillator Frequency
RFS = 350k
70
kHz
RFS = 36k
700
kHz
DCON(MIN)
Minimum Switch-On Duty Cycle
fOSC = 200kHz
6
9
%
DCON(MAX)
Maximum Switch-On Duty Cycle
fOSC = 200kHz
70
80
95
%
fSYNC
As a Function of fOSC
70kHz < fOSC < 700kHz,
70kHz < fSYNC < 700kHz
67
133
%
VSYNC
Minimum SYNC Amplitude
2.9
V
ISS
Soft-Start Current
–6
μA
IFTO
Fault Timeout Current
2μA
tSS(INT)
Internal Soft-Start Time
No External Capacitor on SSFLT
1.8
ms
tFTO(INT)
Internal Fault Timeout
No External Capacitor on SSFLT
4.5
ms
tRISE
Gate Drive Rise Time
CLOAD = 3000pF
30
ns
tFALL
Gate Drive Fall Time
CLOAD = 3000pF
30
ns
VI(MAX)
Peak Current Sense Voltage
RSL = 0 (Note 6)
l
85
100
115
mV
ISL(MAX)
Peak Slope Compensation Output Current
(Note 7)
10
μA
VOCT
Overcurrent Threshold
ROC = 0 (Note 8)
l
85
100
115
mV
IOC
Overcurrent Threshold Adjust Current
10
μA
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 5: The LTC3805-5 is tested in a feedback loop that servos VFB to the
output of the error amplier while maintaining ITH at the midpoint of the
current limit range.
Note 6: Peak current sense voltage is reduced dependent on duty cycle
and an optional external resistor in series with the SENSE pin. For
details, refer to Programmable Slope Compensation in the Applications
Information section.
Note 7: Guaranteed by design.
Note 8: Overcurrent threshold voltage is reduced dependent on an
optional external resistor in series with the OC pin. For details, refer to
Programmable Overcurrent in the Applications Information section.
ELECTRICAL CHARACTERISTICS The l denotes the specications which apply over the full operating
junction temperature range, otherwise specications are at TA = 25°C, VCC = 5V, unless otherwise noted (Note 2).