MAX8576EUB Maxim Integrated Products, MAX8576EUB Datasheet - Page 15

• Manufacturer Part Number: MAX8576EUB
• Description: DC/DC Switching Controllers 3-28V Hystrtic Synch Step-Down Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX8576EUB

• Number Of Outputs: 1
• Output Voltage: 0.6 V to 25 V
• Output Current: 15 A
• Input Voltage: 3 V to 28 V
• Mounting Style: SMD/SMT
• Package / Case: uMAX-10
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

N1 operates as a duty-cycle control switch and has the
following major losses: the channel-conduction loss
(P
and the drive loss (P
diode conduction loss because the diode never con-
ducts current.
Use R
where I
capability determined by:
where R
tance (2
tance of the MOSFET (approximately 2 ).
where V
In addition to the losses above, allow about 20% more
for additional losses due to MOSFET output capaci-
tances and N2 body-diode reverse-recovery charge
dissipated in N1 that exists, but is not well defined in
the MOSFET data sheet. Refer to the MOSFET data
sheet for thermal-resistance specification to calculate
the PC board area needed to maintain the desired max-
imum operating junction temperature with the above
calculated power dissipations.
To reduce EMI caused by switching noise, add 0.1µF
ceramic capacitor from the high-side switch drain to the
low-side switch source or add resistors in series with
DH and DL to slow down the switching transitions.
However, adding series resistors increases the power
dissipation of the MOSFET, so be sure this does not
overheat the MOSFET.
The minimum load current must exceed the high-side
MOSFET’s maximum leakage current over temperature
if fault conditions are expected.
N1CC
DS(ON)
P
P
), the VL overlapping switching loss (P
GATE
N SW
GS
N DR
DH
1
1
P
is approximately equal to V
typ) and R
N CC
I
GATE
is the high-side MOSFET driver’s on-resis-
1
at T
is the average DH driver output-current
Q
V
IN
g
J(MAX)
______________________________________________________________________________________
V
V
OUT
V
I
. 0 5
LOAD
N1DR
IN
GS
GATE
.
3V to 28V Input, Low-Cost, Hysteretic
). N1 does not have body-
R
f
S
Synchronous Step-Down Controllers
is the internal gate resis-
DH
I
LOAD
Q
R
gs
V
I
GATE
L
GATE
R
2
GATE
R
GATE
L.
R
Q
DS ON
gd
(
R
DH
)
f
S
N1SW
),
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
ripple on the input caused by the circuit’s switching.
The input capacitor must meet the ripple-current
requirement (I
defined by the following equation:
I
equals twice the output voltage (V
I
mended due to their low ESR and ESL at high frequen-
cy, with relatively lower cost. Choose a capacitor that
exhibits less than 10 C temperature rise at the maximum
operating RMS current for optimum long-term reliability.
The key selection parameters for the output capacitor
are the actual capacitance value, the ESR, the equiva-
lent series inductance (ESL), and the voltage-rating
requirements. These parameters affect the overall sta-
bility, output voltage ripple, and transient response. The
output ripple has three components: variations in the
charge stored in the output capacitor, the voltage drop
across the capacitor’s ESR, and the ESL caused by the
current into and out of the capacitor. The maximum out-
put ripple voltage can be estimated by:
The output voltage ripple as a consequence of the ESR
and output capacitance is:
where I
Inductor Value section). These equations are suitable
for initial capacitor selection, but final values should be
RMS(MAX)
RMS
V
RIPPLE
has a maximum value when the input voltage
I
RMS
P-P
I
= I
P P
is the peak-to-peak inductor current (see the
V
RIPPLE ESL
V
LOAD
RMS
V
RIPPLE ESR
V
I
RIPPLE ESR
LOAD
RIPPLE C
) imposed by the switching currents
(
/ 2. Ceramic capacitors are recom-
V
(
IN
(
( )
)
f
S
)
V
)
OUT
V
L
OUT
V
V
C
RIPPLE C
V
I
L
IN
P P
IN
OUT
I
Output Capacitor
P P
V
Input Capacitor
IN
IN
( )
ESR
ESL
V
f
= 2 x V
S
OUT
V
IN
V
V
RIPPLE ESL
OUT
OUT
(
), so
)
15