MAX17082GTL+ Maxim Integrated Products, MAX17082GTL+ Datasheet - Page 46

• Manufacturer Part Number: MAX17082GTL+
• Description: IC CTLR PWM DUAL IMVP-6.5 40TQFN
• Manufacturer: Maxim Integrated Products
• Series: Quick-PWM™r

Specifications of MAX17082GTL+

• Applications: Controller, Intel IMVP-6.5™
• Voltage - Input: 4.5 ~ 5.5 V
• Number Of Outputs: 1
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 40-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Details

Dual-Phase, Quick-PWM Controllers for
IMVP-6+/IMVP-6.5 CPU Core Power Supplies
The output-voltage-adjustable range for continuous-
conduction operation is restricted by the nonadjustable
minimum off-time one-shot and the number of phases.
For best dropout performance, use the slower (200kHz)
on-time settings. When working with low input voltages,
the duty-factor limit must be calculated using worst-
case values for on- and off-times. Manufacturing toler-
ances and internal propagation delays introduce an
error to the on-times. This error is greater at higher fre-
quencies. Also, keep in mind that transient-response
performance of buck regulators operated too close to
dropout is poor, and bulk output capacitance must
often be added (see the V
Multiphase Quick-PWM Design Procedure section.
The absolute point of dropout is when the inductor cur-
rent ramps down during the minimum off-time (ΔI
as much as it ramps up during the on-time (ΔI
ratio h = ΔI
slew the inductor current higher in response to
increased load, and must always be greater than 1. As
h approaches 1, the absolute minimum dropout point,
the inductor current cannot increase as much during
each switching cycle and V
unless additional output capacitance is used.
A reasonable minimum value for h is 1.5, but adjusting
this up or down allows tradeoffs between V
capacitance, and minimum operating voltage. For a
given value of h, the minimum operating voltage can be
calculated as:
where η
switching regulators, V
droop, V
in the discharge and charge paths (see the On-Time
One-Shot section), t
Characteristics table. The absolute minimum input volt-
age is calculated with h = 1.
If the calculated V
minimum input voltage, then reduce the operating fre-
quency or add output capacitance to obtain an accept-
able V
calculate V
response.
46
V
______________________________________________________________________________________
IN MIN
Minimum Input-Voltage Requirements
SAG
(
DIS
TOTAL
)
. If operation near dropout is anticipated,
UP
=
and V
SAG
η
/ΔI
TOTAL
is the total number of out-of-phase
DOWN
V
to be sure of adequate transient
CHG
CHG
IN(MIN)
⎡
⎢
⎢
⎣
OFF(MIN)
and Dropout Performance
-
- 1
are the parasitic voltage drops
is an indicator of the ability to
V
FB
DIS
η
V
is greater than the required
TOTAL
FB
is the voltage-positioning
+
-
V
SAG
V
DROOP
SAG
DROOP
is from the Electrical
h t
×
greatly increases
OF
equation in the
F F MIN SW
+
(
V
DIS
SAG
)
f
UP
, output
DOWN
⎤
⎥
⎥
⎦
). The
+
)
Dropout design example:
V
f
t
V
V
h = 1.5 and η
Calculating again with h = 1 gives the absolute limit of
dropout:
Therefore, V
large output capacitance, and a practical input voltage
with reasonable output capacitance would be 5.0V.
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. The switching
power stage requires particular attention. If possible,
mount all the power components on the top side of the
board with their ground terminals flush against one
another. Refer to the MAX17082 evaluation kit specifi-
cation for a layout example and follow these guidelines
for good PCB layout:
•
•
•
SW
OFF(MIN)
FB
DROOP
DIS
Keep the high-current paths short, especially at the
ground terminals. This is essential for stable, jitter-
free operation.
Connect all analog grounds to a separate solid cop-
per plane, which connects to the GND pin of the
Quick-PWM controller. This includes the V
and GNDS bypass capacitors.
Keep the power traces and load connections short.
This is essential for high efficiency. The use of thick
copper PCBs (2oz vs. 1oz) can enhance full-load
efficiency by 1% or more. Correctly routing PCB
traces is a difficult task that must be approached in
terms of fractions of centimeters, where a single mΩ
of excess trace resistance causes a measurable
efficiency penalty.
= 300kHz
= 1.4V
= V
V
V
IN MIN
IN MIN
CHG
(
= 3mV/A x 30A = 90mV
(
= 400ns
IN
150
)
150
)
= 150mV (30A Load)
TOTAL
=
=
must be greater than 4.1V, even with very
Applications Information
2
mV
2
mV
×
×
⎡
⎢
⎣
-
⎡
⎢
⎣
-
= 2:
1 2
150
1 2
150
-
-
1 4
1 4
mV
×
mV
×
.
.
( .
PCB Layout Guidelines
( .
V
0 4
V
0 4
+
+
-
-
90
90
μs
90
90
μs
mV
mV
mV
mV
×
×
1 5
1 0
.
.
+
=
+
=
150
4 96
150
×
4 07
×
.
.
3 3 00
3 3 00
mV
mV
V
V
kHz
kHz
)
)
⎤
⎥ +
⎦
⎤
⎥ +
⎦
CC
, FB,