IC PWR SUPPLY DDR 28-TQFN

MAX8632ETI+T

Manufacturer Part NumberMAX8632ETI+T
DescriptionIC PWR SUPPLY DDR 28-TQFN
ManufacturerMaxim Integrated Products
MAX8632ETI+T datasheet
 


Specifications of MAX8632ETI+T

ApplicationsController, DDRVoltage - Input2 ~ 28 V
Number Of Outputs1Voltage - Output1.8V, 2.5V, 0.7 ~ 5.5 V
Operating Temperature-40°C ~ 85°CMounting TypeSurface Mount
Package / Case28-TQFN Exposed PadOutput Voltage1.8 V, 2.5 V, 0.7 V to 5.5 V
Output Current15 AInput Voltage2 V to 28 V
Mounting StyleSMD/SMTMaximum Operating Temperature+ 85 C
Minimum Operating Temperature- 40 CLead Free Status / RoHS StatusLead free / RoHS Compliant
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Integrated DDR Power-Supply Solution for
Desktops, Notebooks, and Graphic Cards
LX
MAX8632
DL
Q2
PGND1
GND
OUT
FB
Figure 6. Setting V OUT with a Resistive Voltage-Divider
to 200kHz. The core must be large enough not to satu-
rate at the peak inductor current (I
=
I
I
PEAK
LOAD MAX
(
)
Most inductor manufacturers provide inductors in stan-
dard values, such as 1.0µH, 1.5µH, 2.2µH, 3.3µH, etc.
Also look for nonstandard values, which can provide a
better compromise in LIR across the input voltage range.
If using a swinging inductor (where the no-load induc-
tance decreases linearly with increasing current), evalu-
ate the LIR with properly scaled inductance values.
Input Capacitor Selection (Buck)
The input capacitor must meet the ripple current
requirement (I
) imposed by the switching currents:
RMS
(
V
V
OUT IN
=
I
I
RMS
LOAD
V
I
has a maximum value of I
RMS
LOAD
V
. For most applications, nontantalum capacitors
OUT
(ceramic, aluminum, POS, or OSCON) are preferred
due to their resistance to power-up surge currents typi-
cal of systems with a mechanical switch or connector in
series with the input. If the MAX8632 is operated as the
second stage of a two-stage power conversion system,
tantalum input capacitors are acceptable. In either con-
figuration, choose a capacitor that has less than 10°C
______________________________________________________________________________________
temperature rise at the RMS input current for optimal
reliability and lifetime.
L
V
OUT
The output filter capacitor must have low enough equiv-
C
OUT
alent series resistance (R
load-transient requirements, yet have high enough ESR
to satisfy stability requirements.
For processor core voltage converters and other appli-
cations in which the output is subject to violent load
transients, the output capacitor’s size depends on how
much R
ping too low under a load transient. Ignoring the sag
R
C
due to finite capacitance:
R
D
In applications without large and fast load transients,
the output capacitor’s size often depends on how much
R
is needed to maintain an acceptable level of out-
ESR
put voltage ripple. The output ripple voltage of a step-
down controller is approximately equal to the total
):
inductor ripple current multiplied by the output capaci-
PEAK
tor’s R
ESR
LIR
meet ripple specifications is:
+
1
2
The actual capacitance value required relates to the
physical size needed to achieve low ESR, as well as to
the chemistry of the capacitor technology. Thus, the
capacitor is usually selected by ESR and voltage rating
rather than by capacitance value (this is true of tanta-
lums, OSCONs, polymers, and other electrolytics).
When using low-capacity filter capacitors, such as
ceramic capacitors, size is usually determined by the
capacity needed to prevent V
)
-
V
causing problems during load transients. Generally,
OUT
once enough capacitance is added to meet the over-
IN
shoot requirement, undershoot at the rising load edge
= 2 ×
is no longer a problem (see the V
/ 2 when V
IN
tions in the Transient Response (Buck) section).
However, low-capacity filter capacitors typically have
high-ESR zeros that can affect the overall stability (see
the Stability Requirements section).
Output Capacitor Selection (Buck)
) to meet output ripple and
ESR
is needed to prevent the output from dip-
ESR
V
STEP
R
ESR
I
LOAD MAX
(
)
. Therefore, the maximum R
ESR
V
RIPPLE
R
ESR
×
I
LIR
LOAD MAX
(
)
and V
SAG
and V
SAG
required to
from
SOAR
equa-
SOAR
19