LTC3831
3
3831fb
ELECTRICAL CHARACTERISTICS
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: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specifi ed.
Note 3: Supply current in normal operation is dominated by the current
needed to charge and discharge the external FET gates. This will vary with
the LTC3831 operating frequency, operating voltage and the external FETs
used.
Note 4: The LTC3831EGN is guaranteed to meet performance
specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 85°C
operating temperature range are assured by design, characterization
and correlation with statistical process controls. The LTC 3831IGN is
guaranteed to meet performance specifi cations over the full –40°C to 85°C
temperature range.
The ● denotes specifi cations that apply over the full operating temperature
range, otherwise specifi cations are at T
A
= 25°C. V
CC
, PV
CC1
, PV
CC2
= 5V, V
R
+ = 2.5V, V
R
– = GND, unless otherwise noted. (Note 2)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
COMPMAX
Maximum V
COMP
V
FB
= 0V, PV
CC1
= 8V 2.85 V
Δf
OSC
/ΔI
FREQSET
Frequency Adjustment 10 kHz/µA
A
V
Error Amplifi er Open-Loop DC Gain
●
46 55 dB
g
m
Error Amplifi er Transconductance
●
520 650 780 µmho
I
COMP
Error Amplifi er Output Sink/Source
Current
100 µA
I
MAX
I
MAX
Sink Current V
IMAX
= V
CC
●
9
4
12
12
15
20
µA
µA
I
MAX
Sink Current Tempco V
IMAX
= V
CC
(Note 6) 3300 ppm/°C
V
IH
SHDN Input High Voltage
●
2.4 V
V
IL
SHDN Input Low Voltage
●
0.8 V
I
IN
SHDN Input Current V
SHDN
= V
CC
●
0.1 1 µA
I
SS
Soft-Start Current V
SS
= 0V, V
IMAX
= 0V, V
IFB
= V
CC
●
–8 –12 –16 µA
I
SSIL
Maximum Soft-Start Sink Current
Undercurrent Limit
V
IMAX
= V
CC
, V
IFB
= 0V, V
SS
= V
CC
(Note 8),
PV
CC1
= 8V
1.6 mA
R
+
R
+
Input Resistance 49.5 kΩ
t
r,
t
f
Driver Rise/Fall Time Figure 2, PV
CC1
= PV
CC2
= 5V (Note 5)
●
80 250 ns
t
NOV
Driver Nonoverlap Time Figure 2, PV
CC1
= PV
CC2
= 5V (Note 5)
●
25 120 250 ns
DC
MAX
Maximum TG Duty Cycle Figure 2, V
FB
= 0V (Note 5), PV
CC1
= 8V
●
91 95 %
Note 5: Rise and fall times are measured using 10% and 90% levels. Duty
cycle and nonoverlap times are measured using 50% levels.
Note 6: Guaranteed by design, not subject to test.
Note 7: PV
CC1
must be higher than V
CC
by at least 2.5V for TG to operate
at 95% maximum duty cycle and for the current limit protection circuit to
be active.
Note 8: The current limiting amplifi er can sink but cannot source current.
Under normal (not current limited) operation, the output current will be
zero.
Note 9: This IC includes overtemperature protection that is intended to protect
the device during momentary overload conditions. Junction temperature
will exceed 125°C when overtemperature protection is active. Continuous
operation above the specifi ed maximum operating junction temperature may
impair device reliability.
