LTC3831-1 Linear Technology, LTC3831-1 Datasheet - Page 7

• Manufacturer Part Number: LTC3831-1
• Description: High Power Synchronous Switching Regulator Controller
• Manufacturer: Linear Technology

www.datasheet4u.com
BLOCK DIAGRA
transient response.
FREQSET (Pin 11): Frequency Set. Use this pin to adjust
the free-running frequency of the internal oscillator. With
the pin floating, the oscillator runs at about 300kHz. A
resistor from FREQSET to ground speeds up the oscillator;
a resistor to V
I
threshold for the internal current limit comparator. If I
drops below I
current limit. I
Connect this pin to the main V
through an external resistor to set the current limit thresh-
old. Connect a 0.1 F decoupling capacitor across this
resistor to filter switching noise.
I
switching node at the source of Q1 and the drain of Q2
PI FU CTIO S
MAX
FB
U
(Pin 13): Current Limit Sense. Connect this pin to the
(Pin 12): Current Limit Threshold Set. I
U
FREQSET
MAX
MAX
CC
COMP
SHDN
slows it down.
SS
has an internal 12 A pull-down to GND.
with TG on, the LTC3831-1 goes into
U
Q
C
W
12 A
100 s DELAY
OSCILLATOR
IN
INTERNAL
supply at the drain of Q1,
2.2V
1.2V
QSS
V
+
REF
ERR
DISABLE
–
I
LIM
THERMAL SHUTDOWN
–
+
CC
LOGIC AND
MAX
PWM
–
+
sets the
POWER DOWN
12 A
FB
V
I
I
REF
FB
MAX
V
through a 1k resistor. The 1k resistor is required to prevent
voltage transients from damaging I
sensing the voltage drop across the upper N-channel
MOSFET, Q1.
V
circuits draw their supply from this pin. This pin requires
a 4.7 F bypass capacitor to GND.
PV
pin to the main high power supply.
BG (Pin 16): Bottom Driver Output . Connect this pin to the
gate of the lower N-channel MOSFET, Q2. This output
swings from PGND to PV
high or during shutdown mode. To prevent output under-
shoot during a soft-start cycle, BG is held low until TG first
goes high (FFBG in the Block Diagram).
–
+ 10%
DISABLE GATE DRIVE
CC
MAX
+
–
CC2
(Pin 14): Power Supply Input. All low power internal
+
PV
V
(Pin 15): Power Supply Input for BG. Connect this
CC
POR
CC1
+ 2V
S
R
S
R
FFBG
Q
Q
Q
ENABLE
BG
V
REF
+ 10%
CC2
V
REF
. It remains low when TG is
24k
2.66k
2.66k
24k
FB
38311 BD
.This pin is used for
LTC3831-1
V
PV
TG
PV
BG
PGND
FB
R
R
GND
CC
+
–
CC1
CC2
38311f
7