MAX15035 Datasheet, PDF (11/27 Pages) Maxim Integrated Products – 15A Step-Down Regulator with Internal Switches

15A Step-Down Regulator with Internal Switches
Pin Description (continued)
PIN
NAME
FUNCTION
Feedback Voltage Sense Connection. Connect directly to the positive terminal of the output capacitors
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FB
for output voltages less than 2V as shown in Figure 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.
Current-Limit Threshold Adjustment. The current-limit threshold is 0.05 times (1/20) the voltage at
33
ILIM
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).
External Reference Input. REFIN sets the feedback regulation voltage (V_FB = V_REFIN) of the
34
REFIN
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.
Pulse-Skipping Control Input. This four-level input determines the mode of operation under normal
steady-state conditions and dynamic output-voltage transitions:
36
SKIP
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)
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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.
Open-Drain Power-Good Output. PGOOD is low when the output voltage is more than 200mV (typ)
38
PGOOD ^{below or 300mV (typ) above the target voltage (VREFIN), 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)
Exposed Pad 2/Inductor Connection. Internally connected to drain of the low-side MOSFET and
LX
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).
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