LTC3418 Datasheet, PDF (5/20 Pages) Linear Technology – 8A, 4MHz, Monolithic Synchronous Step-Down Regulator

LTC3418
TYPICAL PERFOR A CE CHARACTERISTICS T_A = 25°C unless otherwise noted.
Peak Inductor Current
vs Burst Clamp Voltage
12
10
8
Load Regulation
0
–0.05
–0.10
V_IN = 3.3V
V_OUT = 1.8V
f = 1MHz
Load Step Transient
OUTPUT
VOLTAGE
100mV/DIV
6
4
5V
2
3.3V
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
V_BCLAMP (V)
3418 G13
Load Step Transient
–0.15
–0.20
–0.25
–0.30
0 1234 56
LOAD CURRENT (A)
Burst Mode Operation
78
3418 G14
INDUCTOR
CURRENT
5A/DIV
V_IN = 3.3V
20µs/DIV
V_OUT = 2.5V
LOAD STEP: 800mA TO 8A
Start-Up Transient
3418 G15
OUTPUT
VOLTAGE
100mV/DIV
INDUCTOR
CURRENT
5A/DIV
V_IN = 3.3V
40µs/DIV
V_OUT = 2.5V
LOAD STEP: 3A TO 8A
OUTPUT
VOLTAGE
100mV/DIV
INDUCTOR
CURRENT
1A/DIV
3418 G16
V_IN = 3.3V
V_OUT = 2.5V
LOAD: 200mA
20µs/DIV
OUTPUT
VOLTAGE
500mV/DIV
3418 G17
INDUCTOR
CURRENT
2A/DIV
V_IN = 3.3V
V_OUT = 2.5V
LOAD: 8A
1ms/DIV
3418 G18
PI FU CTIO S
SW (Pins 1, 2, 11, 12, 20, 21, 30, 31): Switch Node
Connection to Inductor. This pin connects to the drains of
the internal main and synchronous power MOSFET
switches.
PV_IN (Pins 3, 4, 9, 10, 22, 23, 28, 29): Power Input
Supply. Decouple this pin to PGND with a capacitor.
PGOOD (Pin 5): Power Good Output. Open-drain logic
output that is pulled to ground when the output voltage is
not within ±7.5% of regulation point.
R_T (Pin 6): Oscillator Resistor Input. Connecting a resistor
to ground from this pin sets the switching frequency.
RUN/SS (Pin 7): Run Control and Soft-Start Input. Forcing
this pin below 0.5V shuts down the LTC3418. In shutdown
all functions are disabled drawing <1.5µA of supply cur-
rent. A capacitor to ground from this pin sets the ramp
time to full output current.
SGND (Pin 8): Signal Ground. All small-signal compo-
nents and compensation components should connect to
this ground, which in turn connects to PGND at one point.
PGND (Pins 13, 14, 15, 17, 18, 19, 32, 33, 34, 36, 37,
38): Power Ground. Connect this pin closely to the (–)
terminal of C_IN and C_OUT.
V_REF (Pin 16): Reference Output. Decouple this pin with a
2.2µF capacitor.
SV_IN (Pin 24): Signal Input Supply. Decouple this pin to
SGND with a capacitor.
3418f
5