Datasheet

LTC3805
3
3805fg
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
TURNON
V
CC
Turn-On Voltage
l
7.75 8.4 9 V
V
TURNOFF
V
CC
Turn-Off Voltage
l
3.75 3.95 4.15 V
V
HYST
V
CC
Hysteresis 4.5 V
V
CLAMP1mA
V
CC
Shunt Regulator Voltage V
CC
Sinking 1mA, V
RUN
= 0
l
8.8 9.25 9.65 V
V
CLAMP25mA
V
CC
Shunt Regulator Voltage V
CC
Sinking 25mA, V
RUN
= 0
l
8.9 9.5 9.9 V
I
CC
Input DC Supply Current Normal Operation (f
OSC
= 200kHz)
(Note 4)
360 µA
V
RUN
< V
RUNON
or V
CC
< V
TURNON
– 100mV
(Micropower Start-Up)
l
40 90 µA
V
RUNON
RUN Turn-On Voltage V
CC
Sinking 1mA
l
1.122 1.207 1.292 V
V
RUNOFF
RUN Turn-Off Voltage V
CC
Sinking 1mA
l
1.092 1.170 1.248 V
I
RUN(HYST)
RUN Hysteresis Current
l
4 5 5.8 µA
V
FB
Regulated Feedback Voltage 0°C ≤ T
J
≤ 85°C (E-Grade) (Note 5)
–40°C ≤ T
J
≤ 85°C (E-Grade) (Note 5)
–40°C ≤ T
J
≤ 125°C (I-Grade) (Note 5)
–40°C ≤ T
J
≤ 150°C (H-Grade) (Note 5)
–55°C ≤ T
J
≤ 150°C (MP-Grade)
l
l
l
l
0.788
0.780
0.780
0.770
0.770
0.800
0.800
0.800
0.800
0.800
0.812
0.812
0.812
0.820
0.820
V
V
V
V
V
I
FB
V
FB
Input Current V
ITH
= 1.3V (Note 5) 20 nA
g
m
Error Amplifier Transconductance I
TH
Pin Load = ±5µA (Note 5) 333 µA/V
∆V
O(LINE)
Output Voltage Line Regulation V
TURNOFF
< V
CC
< V
CLAMP1mA
(Note 5) 0.05 mV/V
∆V
O(LOAD)
Output Voltage Load Regulation I
TH
Sinking 5µA (Note 5)
I
TH
Sourcing 5µA (Note 5)
3
3
mV/µA
mV/µA
f
OSC
Oscillator Frequency R
FS
= 350k 70 kHz
R
FS
= 36k 700 kHz
DC
ON(MIN)
Minimum Switch-On Duty Cycle f
OSC
= 200kHz 6 9 %
DC
ON(MAX)
Maximum Switch-On Duty Cycle f
OSC
= 200kHz 70 80 95 %
f
SYNC
As a Function of f
OSC
70kHz < f
OSC
< 700kHz,
70kHz < f
SYNC
< 700kHz
67 133 %
V
SYNC
Minimum SYNC Amplitude 2.9 V
I
SS
Soft-Start Current –6 µA
I
FTO
Fault Timeout Current 2 µA
t
SS(INT)
Internal Soft-Start Time No External Capacitor on SSFLT 1.8 ms
t
FTO(INT)
Internal Fault Timeout No External Capacitor on SSFLT 4.5 ms
t
RISE
Gate Drive Rise Time C
LOAD
= 3000pF 30 ns
t
FALL
Gate Drive Fall Time C
LOAD
= 3000pF 30 ns
V
I(MAX)
Peak Current Sense Voltage R
SL
= 0 (Note 6)
l
85 100 115 mV
I
SL(MAX)
Peak Slope Compensation Output
Current
(Note 7) 10 µA
V
OCT
Overcurrent Threshold R
OC
= 0 (Note 8)
l
85 100 115 mV
I
OC
Overcurrent Threshold Adjust Current 10 µA
electrical characteristics
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C, V
CC
= 8V, unless otherwise noted (Note 2).