MAX15051EWE+T Maxim Integrated Products, MAX15051EWE+T Datasheet - Page 11

• Manufacturer Part Number: MAX15051EWE+T
• Description: Switching Converters, Regulators & Controllers 4A DC/DC CONVTR egulator with Integr
• Manufacturer: Maxim Integrated Products

Specifications of MAX15051EWE+T

• Output Current: 4 A
• Input Voltage: 2.9 V to 5.5 V
• Switching Frequency: 1 MHz
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 96 %
• Package / Case: WLP-16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX15050/MAX15051 output voltage is adjustable
from 0.6V to 90% of V
tap of a resistor-divider between the output and GND
(Figure 3). To determine the values of the resistor-
divider, first select the value of R3 between 2kΩ and
10kΩ. Then use the following equation to calculate R4:
where V
REFIN/SS and V
V
REFIN/SS, the internal reference is automatically select-
ed and V
Drive EN to GND to shut down the device and reduce
quiescent current to less than 10µA. During shutdown,
LX is high impedance. Drive EN high to enable the
MAX15050/MAX15051.
Thermal-overload protection limits total power dissipa-
tion in the device. When the junction temperature
exceeds T
device into shutdown, allowing the die to cool. The ther-
mal sensor turns the device on again after the junction
temperature cools by 20°C, causing a pulsed output
during continuous overload conditions. The soft-start
sequence begins after recovery from a thermal-shut-
down condition.
To decrease the noise effects due to the high switching
frequency and maximize the output accuracy of
the MAX15050/MAX15051, decouple V
capacitor in parallel with a 0.1µF capacitor from V
GND. Also decouple V
to GND. Place these capacitors as close as possible to
the device.
Choose an inductor with the following equation:
where LIR is the ratio of the inductor ripple current to
full load current at the minimum duty cycle and f
switching frequency (1MHz). Choose LIR between 20%
to 40% for best performance and stability.
Use an inductor with the lowest possible DC resistance
that fits in the allotted dimensions. Powdered iron or fer-
with Integrated Switches in 2mm x 2mm Package
FB
High-Efficiency, 4A, 1MHz, Step-Down Regulators
, remove R4. If no external reference is applied at
FB
FB
J
becomes 0.6V.
R4 = (V
is equal to the reference voltage at
= +165°C, a thermal sensor forces the
L
Applications Information
OUT
=
______________________________________________________________________________________
f
S
Setting the Output Voltage
FB
is the output voltage. For V
×
V
DD
IN
OUT
V
x R3)/(V
IN
by connecting FB to the center
with a 2.2µF capacitor from V
IN and V
×
×
LIR I
(
V
Thermal Protection
IN
Inductor Selection
OUT
×
−
OUT MAX
Shutdown Mode
V
OUT
- V
DD
(
FB
)
IN
Decoupling
)
)
with a 22µF
S
OUT
is the
IN
DD
to
=
Figure 3. Setting the Output Voltage with a Resistor Voltage-
Divider
rite core types are often the best choice for perfor-
mance. With any core material, the core must be large
enough not to saturate at the current limit of the
MAX15050/MAX15051.
The key selection parameters for the output capacitor
are capacitance, ESR, ESL, and voltage-rating require-
ments. These affect the overall stability, output ripple
voltage, and transient response of the DC-DC convert-
er. The output ripple occurs due to variations in the
charge stored in the output capacitor, the voltage drop
due to the capacitor’s ESR, and the voltage drop due to
the capacitor’s ESL. Estimate the output-voltage ripple
due to the output capacitance, ESR, and ESL as fol-
lows:
where the output ripple due to output capacitance,
ESR, and ESL is:
whichever is higher.
and
MAX15050
MAX15051
V
V
V
RIPPLE C
RIPPLE ESR
V
RIPPLE ESL
RIPPLE ESL
V
RIPPLE ESR
V
RIPPLE
( )
Output-Capacitor Selection
(
LX
FB
(
(
(
=
)
)
8
)
=
=
=
=
)
x C
I
P P
I
V
P P
t
+
I
t
ON
RIPPLE C
−
P P
OFF
−
I
V
P P
OUT
−
RIPPLE ESL
−
x
x x ESL or
x ESL
E E SR
( )
x f
R3
R4
S
(
+
)
11