Datasheet

LTC3860
9
3860fc
FUNCTIONAL DIAGRAM
PIN FUNCTIONS
A change in V
IN
immediately modulates the input to the
PWM comparator and changes the pulse width in an in-
versely proportional manner, thus bypassing the feedback
loop and providing excellent transient line regulation. An
external lowpass fi lter can be added to this pin to prevent
noisy signals from affecting the loop gain.
TRACK/SS1 (Pin 32), TRACK/SS2 (Pin 9): Soft-Start. The
voltage ramp rate at these pins sets the voltage ramp rate
of the outputs. Self soft-start is accomplished by placing
a capacitor to ground.
22
ISNS1P
21
ISNS1N
20
231828
ISNS2N
I
AVG
I
LIM2
I
LIM1
20μA
21μA
20μA
10
FREQ
13
PHSMD
12
CLKOUT
11
16
CLKIN
3860 BD
OC1
NOC1
OC2
NOC2
19
ISNS2P
x18.5
x18.5
8
FB2
7
COMP2
9
TRACK/SS2
EA2
REF
REF
2
FB1
32
TRACK/SS1
3
COMP1
EA1
+
+
–
+
+
–
+
–
+
–
5
VSNSN
24
RUN1
100k
V
CC
1.5μA
1.5μA
V
CC
17
RUN2
6
VSNSP
4
VSNSOUT
DA
S
V
FB1
I
LIM1
V
FB2
I
LIM2
S
MASTER/SLAVE/
INDEPENDENT?
SD/UVLO
27
PGOOD1
V
FB1
V
FB2
14
PGOOD2
RAMP/SLOPE/
FEEDFORWARD
PGOOD
LOGIC
OC1 OC2
OV1 OV2
NOC1
NOC2
PWM2
31
VINSNS
25
PWM1
15
PWMEN2
26
PWMEN1
PLL/VCO
BG/BIAS
V
CC
V
CC
V
CC
100k
V
CC
1
V
CC
29
SGND
30
SGND
+
+