lt3710 Linear Technology Corporation, lt3710 Datasheet - Page 5

• Manufacturer Part Number: lt3710
• Description: Secondary Side Synchronous Post Regulator
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
BOOST (Pin 1): Topside (Boosted) Driver Supply. This pin
is used to bootstrap and supply the topside power switch
gate drive circuitry. In normal operation V
from the internally generated 8V GBIAS, V
8.2V when TGATE is on.
TGATE (Pin 2): Topside (Boosted) N-Channel MOSFET
Driver. When TGATE is on, the voltage is equal to V
SW (Pin 3): Switch Node Connection to Inductor.
CSET (Pin 4): Oscillator Timing Pin. The capacitor on this
pin sets the PWM switching frequency.
SYNC (Pin 5): Synchronization Input. This pin should be
connected to the secondary side output of the power
transformer with a series resistor. A filtering capacitor of
10pF is recommended.
ILCOMP (Pin 6): Current Limit Amplifier Compensation
Node. At current limit, CA1 pulls down on this pin to
regulate the output current.
SS (Pin 7): Soft-Start. A capacitor on this pin sets the
output ramp up rate. The typical time for SS to reach the
programmed level is (C • 0.8V)/10 A.
V
divider to this pin sets the output voltage. Nominal voltage
at this pin is 0.8V.
FB
U
(Pin 8): Voltage Amplifier Inverting Input. A resistor
U
U
BOOST
BOOST
is powered
= V
SW
+ 6V.
SW
+
BGS (Pin 9): Bottom Gate Switching Control. CA2 moni-
tors the inductor current and prohibits BGATE from turn-
ing on when the inductor current is low (below 8mV across
the current sense resistor RS1) to allow discontinous
mode operation. Grounding this pin disables comparator
CA2.
VA
CL
threshold is set at 70mV.
CL
When used, CL
of the current + sense resistor and CL
inductor side of the current sense resistor.
V
ESR capacitor is required.
PGND (Pin 14): Ground of the Bottom Side N-Channel
MOSFET Driver.
BGATE (Pin 15): Bottom Side N-Channel MOSFET Driver.
GBIAS (Pin 16): 8V Regulator Output for Boostrapping
V
Exposed Pad (Pin 17): Connect to PGND (Pin 14).
CC
BOOST .
+
–
OUT
(Pin 13): Supply of the IC. For proper bypassing, a low
(Pin 11): Current Limit Amplifier Positive Input. The
(Pin 12): Current Limit Amplifier Negative Input.
(Pin 10): Voltage Amplifier Output.
A bypass capacitor of at least 2 F is needed.
–
is connected to the output capacitor side
+
is connected to the
LT3710
5
3710f