Low-Voltage, Internal Switch,
Step-Down Regulator
SET
VCC
OPEN
REF
GND
FREQ
VCC
OPEN
REF
GND
C1
1μF
ON OFF
FB REGULATION
VOLTAGE (V)
1.8
1.5
1.1
0.75
SWITCHING
FREQUENCY (MHz)
1.5
1.0
0.75
0.5
C3
0.1μF
(OPEN)
VCC
IN
EN
BST
SET
LX
MAX17083
REF
FB
FREQ
POK
GND (EP)
COUT
2x 10μF
CBST
0.1μF
L1
1μH
COUT
220μF, 6mΩ
VCC
R4
100kΩ
5V INPUT
OUTPUT
1.1V AT 5A
Figure 1. Standard Application Circuit
Detailed Description
The MAX17083 standard application circuit (Figure 1)
provides a single 1.1V/5A chipset supply. The
MAX17083 features a step-down switching regulator
with dual internal n-channel MOSFET power switches.
These step-down regulators use a fixed-frequency, cur-
rent-mode control scheme compensated by the output
capacitor, providing an easy-to-implement architecture
without sacrificing fast transient response. These regu-
lators also provide peak current-limit protection, and
operate pulse-skipping mode at light loads to maintain
high efficiency.
Independent enable input and open-drain power-good
output allow flexible system power sequencing. The
voltage soft-start gradually ramps up the output voltage
within a predictable time period and reduces inrush
current. The MAX17083 features outputs undervoltage,
output overvoltage, and thermal-fault protection.
Reference (REF)
The 1.25V reference is accurate to ±1% over tempera-
ture and load, making REF useful as a precision system
reference. Bypass REF to GND with a 0.1µF or greater
ceramic capacitor. The reference sources up to 50µA
and sinks 5µA to support external loads. If highly accu-
rate specifications are required for the main SMPS out-
put voltages, the reference should not be loaded.
Loading the reference slightly reduces the output volt-
age accuracy because of the reference load-regulation
error as defined in the Electrical Characteristics table.
8 _______________________________________________________________________________________