Datasheet

LTC3614
8
3614fa
PIN FUNCTIONS
SRLIM/DDR (Pin 1): Slew Rate Limit. Tying this pin to
ground selects maximum slew rate. Minimum slew rate
is selected when the pin is open. Connecting a resistor
from SRLIM/DDR to ground allows the slew rate to be
continuously adjusted. If SRLIM/DDR is tied to S
VIN
, DDR
mode is selected. In DDR mode the slew rate limit is set
to maximum.
RT/SYNC (Pin 2): Oscillator Frequency. This pin provides
three ways of setting the constant switching frequency:
1. Connecting a resistor from RT/SYNC to ground will set
the switching frequency based on the resistor value.
2. Driving the RT/SYNC pin with an external clock signal
will synchronize the LTC3614 to the applied frequency.
The slope compensation is automatically adapted to the
external clock frequency.
3. Tying the RT/SYNC pin to SV
IN
enables the internal
2.25MHz oscillator frequency.
SGND (Pin 3): Signal Ground. All small-signal and compen-
sation components should connect to this ground, which
in turn should connect to PGND at a single point.
PV
IN
(Pins 4, 10, 11, 17): Power Input Supply. PV
IN
con-
nects to the source of the internal P-channel power MOSFET.
This pin is independent of SV
IN
and may be connected to
the same voltage or to a lower voltage supply.
SW (Pins 5, 6, 7, 8, 13, 14, 15, 16): Switch Node. Con-
nection to the inductor. These pins connect to the drains
of the internal power MOSFET switches.
NC (Pins 9, 12): Can be connected to ground or left
open.
SV
IN
(Pin 18): Signal Input Supply. This pin powers
the internal control circuitry and is monitored by the
undervoltage lockout comparator.
Start-Up from Shutdown with
Prebiased Output (Overvoltage)
(Forced Continuous Mode)
Output Voltage During Sinking
vs Input Voltage (V
OUT
= 1.8V,
0.47µH Inductor)
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
= 3.3V, RT/SYNC = SV
IN
unless otherwise noted.
V
OUT
500mV/DIV
PGOOD
5V/DIV
I
L
5A/DIV
50µs/DIV
3614 G31
PREBIASED V
OUT
= 2.2V
V
OUT
= 1.2V, I
OUT
= 0A
V
MODE
= 1.5V
INPUT VOLTAGE (V)
V
OUT
(V)
1.86
1.84
1.82
1.80
1.78
1.88
2.25 4
1.74
1.76
3.252.75 4.5 5.25
3614 G32
–3A, 2MHz, 120°C
–3A, 2MHz, 25°C