LTC3717EGN Linear Technology, LTC3717EGN Datasheet - Page 6

• Manufacturer Part Number: LTC3717EGN
• Description: IC STEP-DWN CONTRLR SYNC 16-SSOP
• Manufacturer: Linear Technology

Specifications of LTC3717EGN

• Applications: Controller, DDR, QDR
• Voltage - Input: 4 ~ 36 V
• Number Of Outputs: 1
• Voltage - Output: 2 ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

PI FU CTIO S
LTC3717
RUN/SS (Pin 1): Run Control and Soft-Start Input. A
capacitor to ground at this pin sets the ramp time to full
output current (approximately 3s/ F) and the time delay
for overcurrent latchoff (see Applications Information).
Forcing this pin below 0.8V shuts down the device.
PGOOD (Pin 2): Power Good Output. Open drain logic
output that is pulled to ground when the output voltage is
not within 10% of the regulation point.
V
this pin is ten times the nominal sense voltage at maxi-
mum output current and can be set from 0.5V to 2V by a
resistive divider from INTV
defaults to 70mV when this pin is tied to ground, 140mV
when tied to INTV
I
Compensation Point. The current comparator threshold
increases with this control voltage. The voltage ranges
from 0V to 2.4V with 0.8V corresponding to zero sense
voltage (zero current).
SGND (Pin 5): Signal Ground. All small-signal compo-
nents and compensation components should connect to
this ground, which in turn connects to PGND at one point.
I
to this pin to set the one-shot timer current and thereby set
the switching frequency.
V
connects to V
through precision internal resistors before it is applied to
the input of the error amplifier. Do not apply more than
1.5V on V
resistor R2 (1/2 • R1 at V
V
This pin connects to an external reference and divides its
voltage to 1/3 V
6
TH
ON
RNG
FB
REF
U
(Pin 4): Current Control Threshold and Error Amplifier
(Pin 6): On-Time Current Input. Tie a resistor from V
(Pin 7): Error Amplifier Feedback Input. This pin
(Pin 8): Positive Input of Internal Error Amplifier.
(Pin 3): Sense Voltage Range Input. The voltage at
FB
U
. For higher output voltages, attach an external
OUT
REF
CC
and divides its voltage to 2/3 • V
U
.
through precision internal resisters
REF
CC
) from V
. The nominal sense voltage
OUT
to V
FB
.
FB
IN
before it is applied to the positive input of the error
amplifier. Reference voltage for output voltage, power
good threshold, and short-circuit shutdown threshold. Do
not apply more than 3V on V
used, connect an external resistor (R1
voltage reference to V
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
range. Decouple this pin to 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 ceramic capacitor.
BG (Pin 12): Bottom Gate Drive. Drives the gate of the
bottom N-channel MOSFET between ground and INTV
PGND (Pin 13): Power Ground. Connect this pin closely to
the source of the bottom N-channel MOSFET, the (–)
terminal of C
SW (Pin 14): Switch Node. The (–) terminal of the boot-
strap capacitor C
diode voltage drop below ground up to a diode voltage
drop above V
TG (Pin 15): 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 16): Boosted Floating Driver Supply. The (+)
terminal of the bootstrap capacitor C
pin swings from a diode voltage drop below INTV
V
CC
IN
+ INTV
(Pin 10): Bias Input Supply. 4V to 36V operating
CC
CC
(Pin 11): Internal 5V Regulator Output. The driver
(Pin 9): External V
CC
VCC
.
IN
.
and the (–) terminal of C
B
connects here. This pin swings from a
REF
.
CC
REF
Input. When EXTV
. If higher voltages are
CC
B
connects here. This
< V
CC
IN
CC
. Do not exceed
.
.
CC
160k) from
superim-
sn3717 3717fs
CC
CC
up to
ex-
CC
CC
.