ltc3827ig-1 Linear Technology Corporation, ltc3827ig-1 Datasheet - Page 8

• Manufacturer Part Number: ltc3827ig-1
• Description: Low Iq, Dual, 2-phase Synchronous Step-down Controller
• Manufacturer: Linear Technology Corporation

FU CTIO AL DIAGRA
LTC3827-1
BG1, BG2 (Pins 23, 18): High Current Gate Drives for
Bottom (Synchronous) N-Channel MOSFETs. Voltage
swing at these pins is from ground to INTV
BOOST1, BOOST2 (Pins 24, 17): Bootstrapped Supplies
to the Top Side Floating Drivers. Capacitors are connected
between the BOOST and SW pins and Schottky diodes are
tied between the BOOST and INTV
at the BOOST pins is from INTV
SW1, SW2 (Pins 25, 16): Switch Node Connections to
Inductors. Voltage swing at these pins is from a Schottky
diode (external) voltage drop below ground to V
TG1, TG2 (Pins 26, 15): High Current Gate Drives for Top
N-Channel MOSFETs. These are the outputs of floating
PI FU CTIO S
8
U
U
V
F
IN
+
R
IN
LP
C
PLLIN/MODE
LP
PGOOD1
PLLLPF
EXTV
INTV
SGND
U
V
27
22
20
19
6
5
7
IN
CC
CC
U
PLLIN/MODE
100k
INTV
OSCILLATOR
4.7V
PHASE DET
CC
-0.5V
U
0.8V
+
–
–
+
–
+
CLK1
CLK2
INTERNAL
–
–
+
+
SUPPLY
5.25V/
7.5V
LDO
0.88V
0.72V
BURSTEN
FC
V
CC
FB1
CC
W
to (V
pins. Voltage swing
DUPLICATE FOR SECOND
CONTROLLER CHANNEL
IN
RUN
8, 9
+ INTV
CC
0.5μA
6V
.
2(V
0.45V
FB
SLOPE
COMP
IN
ICMP
)
CC
.
S
R
).
+
–
Q
Q
0.4V
–
DROP
OUT
DET
2(V
SHDN
+
–
+
RST
FB
+
)
B
6mV
drivers with a voltage swing equal to INTV
superimposed on the switch node voltage SW.
PGOOD1 (Pin 27): Open-Drain Logic Output. PGOOD1 is
pulled to ground when the voltage on the V
within ±10% of its set point.
TRACK/SS1, TRACK/SS2 (Pins 28, 14): External Tracking
and Soft-Start Input. The LTC3827-1 regulates the V
voltage to the smaller of 0.8V or the voltage on the TRACK/
SS1,2 pin. A internal 1μA pull-up current source is con-
nected to this pin. A capacitor to ground at this pin sets the
ramp time to final regulated output voltage. Alternatively,
a resistor divider on another voltage supply connected to
this pin allows the LTC3827-1 output to track the other
supply during startup.
BOT
TOP ON
BURSTEN
–
FOLDBACK
SLEEP
SHDN
FC
–
+
OV
IR
EA
SWITCH
–
+
+
–
LOGIC
SHDN
V
FB
TRACK/SS
0.80V
0.88V
TOP
BOT
1μA
INTV
CC
TRACK/SS
SENSE
SENSE
BOOST
PGND
SW
V
TG
BG
I
21
TH
FB
24, 17
26, 15
25, 16
23, 18
3, 11
4, 10
2, 12
1, 13
28, 14
+
–
INTV
CC
R
D
C
C
C
A
B
C2
SS
B
L
C
R
C
B
V
IN
R
C
R
D
SENSE
FB1
C
IN
CC
pin is not
– 0.5V
38271fd
FB1,2