Datasheet

MAX15035
15A Step-Down Regulator with Internal Switches
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Pin Description (continued)
PIN NAME FUNCTION
32 FB
Feed b ack V ol tag e S ense C onnecti on. C onnect d i r ectl y to the p osi ti ve ter m i nal of the outp ut cap aci tor s
for outp ut vol tag es l ess than 2V as show n i n Fi g ur e 1. For fixed-output voltages greater than 2V,
connect REFIN to REF and use a resistive divider to set the output voltage (Figure 6). FB senses the
output voltage to determine the on-time for the high-side switching MOSFET.
33 ILIM
Current-Limit Threshold Adjustment. The current-limit threshold is 0.05 times (1/20) the voltage at
ILIM. Connect ILIM to a resistive divider (from REF) to set the current-limit threshold between 20mV
and 100mV (with 0.4V to 2V at ILIM).
34 REFIN
External Reference Input. REFIN sets the feedback regulation voltage (V
FB
= V
REFIN
) of the
MAX15035 using a resistor-divider connected between REF and AGND. The MAX15035 includes an
internal window comparator to detect REFIN voltage transitions, allowing the controller to blank
PGOOD and the fault protection.
35 REF
2V Reference Voltage. Bypass to analog ground using a 1nF ceramic capacitor. The reference can
source up to 50μA for external loads.
36 SKIP
Pulse-Skipping Control Input. This four-level input determines the mode of operation under normal
steady-state conditions and dynamic output-voltage transitions:
V
DD
(5V) = Forced-PWM operation
REF (2V) = Pulse-skipping mode (with forced-PWM during transitions)
Open (3.3V) = Ultrasonic mode (without forced-PWM during transitions)
GND = Pulse-skipping mode (without forced-PWM during transitions)
37 V
CC
5V Analog Supply Voltage. Internally connected to V
DD
through an internal 20Ω resistor. Bypass V
CC
to analog ground using a 1μF ceramic capacitor.
38 PGOOD
Open-Drain Power-Good Output. PGOOD is low when the output voltage is more than 200mV (typ)
below or 300mV (typ) above the target voltage (V
REFIN
), during soft-start, and soft-shutdown. After
the soft-start circuit has terminated, PGOOD becomes high impedance if the output is in regulation.
PGOOD is blanked—forced high-impedance state—when a dynamic REFIN transition is detected.
EP1
(41)
AGND
Exposed Pad 1/Analog Ground. Internally connected to the controller’s ground plane and substrate.
Connect directly to ground.
EP2
(42)
LX
Exposed Pad 2/Inductor Connection. Internally connected to drain of the low-side MOSFET and
source of the high-side MOSFET (Figure 2). Connect LX to the switched side of the inductor as
shown in Figure 1.
EP3
(43)
IN
Exposed Pad 3/Power MOSFET Input Power Source. Internally connected to drain of the high-side
MOSFET (Figure 2).