Datasheet

LTC3863
3
3863f
For more information www.linear.com/3863
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Supply
V
IN
Input Voltage Operating Range 3.5 60 V
V
UVLO
Undervoltage Lockout (V
IN
-V
CAP
) Ramping Up Threshold
(V
IN
-V
CAP
) Ramping Down Threshold
Hysteresis
l
l
3.25
3.00
3.50
3.25
0.25
3.8
3.50
V
V
V
I
Q
Input DC Supply Current
Pulse-Skipping Mode PLLIN/MODE = 0V, FREQ = 0V,
V
FB
= 0.83V (No Load)
0.77 1.2 mA
Burst Mode Operation PLLIN/MODE = Open, FREQ = 0V,
V
FB
= 0.83V (No Load)
50 70 µA
Shutdown Supply Current RUN = 0V 7 12 µA
Output Sensing
V
REG
Regulated Feedback Voltage V
REG
= (V
FB
– V
FBN
) V
ITH
= 1.2V (Note 5)
l
0.791 0.800 0.809 V
∆V
REG
∆V
IN
Feedback Voltage Line Regulation V
IN
= 3.8V to 60V (Note 5) –0.005 0.005 %/V
∆V
REG
∆V
ITH
Feedback Voltage Load Regulation V
ITH
= 0.6V to 1.8V (Note 5) –0.1 –0.015 0.1 %
g
m(EA)
Error Amplifier Transconductance V
ITH
= 1.2V, ∆I
ITH
= ±5µA (Note 5) 1.8 mS
I
FBN
Feedback Negative Input Bias Current –50 –10 50 nA
Current Sensing
V
ILIM
Current Limit Threshold (V
IN
-V
SENSE
) V
FB
= 0.77V
l
85 95 103 mV
I
SENSE
SENSE Pin Input Current V
SENSE
= V
IN
0.1 2 µA
Start-Up and Shutdown
V
RUN
RUN Pin Enable Threshold V
RUN
Rising
l
1.22 1.26 1.32 V
V
RUNHYS
RUN Pin Hysteresis 150 mV
I
SS
Soft-Start Pin Charging Current V
SS
= 0V 10 µA
Switching Frequency and Clock Synchronization
f Programmable Switching Frequency R
FREQ
= 24.9kΩ
R
FREQ
= 64.9kΩ
R
FREQ
= 105kΩ
375
105
440
810
505
kHz
kHz
kHz
f
LO
Low Switching Frequency FREQ = 0V 320 350 380 kHz
f
HI
High Switching Frequency FREQ = Open 485 535 585 kHz
f
SYNC
Synchronization Frequency
l
75 750 kHz
V
CLK(IH)
Clock Input High Level into PLLIN/MODE
l
2 V
V
CLK(LO)
Clock Input Low Level into PLLIN/MODE
l
0.5 V
f
FOLD
Foldback Frequency as Percentage of
Programmable Frequency
V
FB
= 0V, V
FREQ
= 0V 18 %
t
ON(MIN)
Minimum On-Time 220 ns
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, unless otherwise noted. (Note 4)