LTC1909-8 LINER [Linear Technology], LTC1909-8 Datasheet - Page 10

• Manufacturer Part Number: LTC1909-8
• Description: Wide Operating Range,No RSENSE TM Step-Down DC/DC Controller with SMBus Programming
• Manufacturer: LINER [Linear Technology]

LTC1909-8
PI FU CTIO S
FB (Pin 17): Feedback Input. Center tap of the SMBus
programmable divider that is connected to Pin 9.
GND (Pin 18): SMBus Programmer Ground. Connect to
regulator signal ground at Pin 7.
V
mer. 2.7V V
pin. Bypass this pin to ground with a 0.1 F ceramic
capacitor if using an external supply.
EXTV
ceeds 4.7V, an internal switch connects this pin to INTV
and shuts down the internal regulator so that controller
and gate drive power is drawn from EXTV
7V at this pin and ensure that EXTV
V
PGND with an RC filter (1 , 0.1 F).
INTV
and control circuits are powered from this voltage. De-
couple this pin to power ground with a minimum of 4.7 F
low ESR tantalum or other low ESR capacitor. The internal
5V regulator is shut down when V
TEST CIRCUIT
10
CC
IN
U
(Pin 19): Positive Supply of the SMBus VID Program-
(Pin 21): Main Input Supply. Decouple this pin to
CC
CC
(Pin 22): Internal 5V Regulator Output. The driver
(Pin 20): External V
U
CC
5.5V. May be connected to the INTV
U
CC
Input. When EXTV
RUN/SS
VRON
CC
SDA
SCL
V
SEL
CC
< V
CC
<1.5V.
. Do not exceed
IN
SMBus VID Programmer Test Circuit
V
SCL
SDA
SEL
VRON
GND
.
CC
CC
CPUON OR
V
PGTMR
OSENSE
ex-
CC
CC
FB
0.8V
5V
BG (Pin 23): Bottom Gate Drive. Drives the gate of the
bottom N-channel MOSFET between ground and INTV
PGND (Pin 24): Power Ground. Connect this pin closely to
the source of the bottom N-channel MOSFET, the (–)
terminal of C
SENSE
(+) input to the current comparator is normally connected
to the SW pin unless using a sense resistor (see Applica-
tions Information).
SW (Pin 26): Switch Node. The (–) terminal of the boot-
strap capacitor C
diode voltage drop below ground up to V
TG (Pin 27): Top Gate Drive. Drives the top N-channel
MOSFET with a voltage swing equal to INTV
posed on the switch node voltage SW.
BOOST (Pin 28): Boosted Floating Driver Supply. The (+)
terminal of the bootstrap capacitor C
pin swings from a diode voltage drop below INTV
V
IN
10k
+ INTV
+
–
S1
S2
+
(Pin 25): Current Sense Comparator Input. The
CC
VCC
.
19098 TC
100pF
0.1 F
and the (–) terminal of C
B
connects here. This pin swings from a
B
connects here. This
IN
IN
.
.
CC
superim-
CC
up to
19098f
CC
.