LTC3873
3
3873fb
For more information www.linear.com/LTC3873
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 LTC3873E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 85°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
• θ
JA
)
Note 4: The dynamic input supply current is higher due to power MOSFET
gate charging (Q
G
• f
OSC
). See Applications Information.
Note 5: The LTC3873 is tested in a feedback loop which servos V
FB
to
the reference voltage with the I
TH
pin forced to the midpoint of its voltage
range (0.7V ≤ V
ITH
≤ 1.9V, midpoint = 1.3V).
Note 6: Rise and fall times are measured at 10% and 90% levels.
V
CC
= 5.6V.
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9V unless otherwise noted. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input DC Supply Current
Normal Operation
Shutdown
UVLO
Typicals
V
ITH
= 1.9V
V
RUN/SS
= 0V
V
CC
= UVLO Threshold – 100mV, V
RUN/SS
= V
CC
300
55
45
400
100
60
µA
µA
µA
Undervoltage Lockout Threshold V
CC
Rising
V
CC
Falling
V
CC
Hysteresis
l
l
l
7.9
3.5
4.0
8.4
4.0
4.4
8.8
4.4
4.8
V
V
V
Shutdown Threshold (at RUN/SS) V
RUN/SS
Falling
V
RUN/SS
Rising
l
0.5
0.6
0.7
0.8
0.9
1.0
V
V
Regulated Feedback Voltage (Note 5)
l
1.182 1.2 1.218 V
Feedback Voltage Line Regulation 5.6V < V
CC
< 9V (Note 5) 0.12 mV/V
Feedback Voltage Load Regulation V
ITH
= 1.6V (Note 5)
V
ITH
= 1V (Note 5)
0.05
–0.05
%
%
V
FB
Input Current (Note 5) 25 50 nA
Maximum Duty Cycle 70 78 84 %
RUN/SS Pull-Up Current V
RUN/SS
= 0V
V
RUN/SS
= 1.3V
1.5
5
3
15
4.5
25
µA
µA
I
SLMAX
, Peak Slope Compensation Current 20 µA
Oscillator Frequency 160 200 240 kHz
Gate Drive Rise Time C
LOAD
= 3000pF (Note 6) 40 ns
Gate Drive Fall Time C
LOAD
= 3000pF (Note 6) 40 ns
Peak Current Sense Voltage IPRG = GND
IPRG = Float
IPRG = V
IN
l
l
l
95
165
265
110
185
295
125
210
325
mV
mV
mV
V
IN
Shunt Regulator Voltage I
IN
= 1mA, I
IN
= 25mA, V
RUN/SS
= 0V
l
9 9.3 9.6 V
Default Internal Soft-Start 3.3 ms
