MAX8632ETI+ Maxim Integrated Products, MAX8632ETI+ Datasheet - Page 19

• Manufacturer Part Number: MAX8632ETI+
• Description: IC PWR SUPPLY DDR 28-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8632ETI+

• Applications: Controller, DDR
• Voltage - Input: 2 ~ 28 V
• Number Of Outputs: 1
• Voltage - Output: 1.8V, 2.5V, 0.7 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Output Voltage: 1.8 V or 2.5 V or 0.7 V to 5.5 V
• Output Current: 15 A
• Input Voltage: 2 V to 28 V
• Supply Current: 25 uA
• Switching Frequency: 600 KHz
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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
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.
The input capacitor must meet the ripple current
requirement (I
I
V
(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
RMS
OUT
has a maximum value of I
. For most applications, nontantalum capacitors
MAX8632
I
RMS
I
PEAK
Input Capacitor Selection (Buck)
RMS
Integrated DDR Power-Supply Solution for
Desktops, Notebooks, and Graphic Cards
=
PGND1
GND
) imposed by the switching currents:
______________________________________________________________________________________
OUT
I
LOAD
LX
DL
FB
=
I
LOAD MAX
V
(
OUT IN
Q2
LOAD
(
)
V



V
L
1
PEAK
IN
+
-
/ 2 when V
LIR
V
):
2
OUT
R
R



V
C
D
OUT
)
C
OUT
IN
= 2 ×
temperature rise at the RMS input current for optimal
reliability and lifetime.
The output filter capacitor must have low enough equiv-
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
due to finite capacitance:
In applications without large and fast load transients,
the output capacitor’s size often depends on how much
R
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-
tor’s R
meet ripple specifications is:
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
causing problems during load transients. Generally,
once enough capacitance is added to meet the over-
shoot requirement, undershoot at the rising load edge
is no longer a problem (see the V
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).
ESR
is needed to maintain an acceptable level of out-
ESR
ESR
. Therefore, the maximum R
Output Capacitor Selection (Buck)
is needed to prevent the output from dip-
R
ESR
R
ESR
≤
≤
I
LOAD MAX
ESR
∆
I
LOAD MAX
V
) to meet output ripple and
(
V
RIPPLE
STEP
SAG
(
SAG
)
×
LIR
)
and V
and V
ESR
SOAR
required to
SOAR
equa-
from
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