MAX1544ETL+ Maxim Integrated Products, MAX1544ETL+ Datasheet - Page 36

• Manufacturer Part Number: MAX1544ETL+
• Description: IC QUICK-PWM DUAL-PHASE 40-TQFN
• Manufacturer: Maxim Integrated Products
• Series: Quick-PWM™r

Specifications of MAX1544ETL+

• Applications: Controller, AMD Hammer
• Voltage - Input: 2 ~ 28 V
• Number Of Outputs: 1
• Voltage - Output: 0.68 ~ 1.55 V
• Operating Temperature: -40°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 40-TQFN Exposed Pad
• Output Voltage: 0.675 V to 1.55 V
• Output Current: 40 A
• Input Voltage: 4 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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
ing regulators, V
V
the discharge and charge paths (see the On-Time One-
Shot (TON) section), t
Characteristics, and K is taken from Table 6. The
absolute minimum input voltage is calculated with h = 1.
If the calculated V
imum input voltage, then reduce the operating frequency
or add output capacitance to obtain an acceptable V
If operation near dropout is anticipated, calculate V
be sure of adequate transient response.
Dual-Phase, Quick-PWM Controller for
AMD Hammer CPU Core Power Supplies
Figure 10. Voltage-Positioning Gain
36
DROP1
V
IN MIN
______________________________________________________________________________________
(
OUTPH
and V
)
=
+
η
V
DROP2
is the total number of out-of-phase switch-
OUTPH
COMPARATOR
DROP
VPS
IN(MIN)
ERROR
2
is the voltage-positioning droop,
are the parasitic voltage drops in






-
1
OFF(MIN)
is greater than the required min-
V
-
DROP
V
MAX1544
η
FB
OUTPH
SAG
-
1
V
+
is from the Electrical
VPS
V



greatly increases
VPS
h x t
+
OAIN+
OAIN-
CMN
CMP
CSN
CSP
V
FB
OFF MIN
DROP
K
SAG
SECOND
(
PHASE
PHASE
MAIN
1
, output
R
SAG
)
F



SAG






to
.
L1
L2
Dropout design example:
V
K
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 5V.
OFF(MIN)
FB
VPS
DROP1
MIN
V
V
IN MIN
IN MIN
= 1.4V
(
(
= 3mV/A × 30A = 90mV
= 3µs for f
R
R
R
R
A
A
SENSE
SENSE
= V
)
)
= 400ns
R
R
B
B
=
=
DROP2
IN
2
2
OUTPH
+
+
must be greater than 4.1V, even with very
x
x
150
150
SW
R






FBS
1 2
1 2
= 150mV (30A load)
mV
mV
= 300kHz
-
-
1 4
1 4
= 2
.
.
V
V
-
-
x
x
PC BOARD TRACE
RESISTANCE
CPU SENSE
POINT
PC BOARD TRACE
RESISTANCE
150
150
-
-
( .
( .
0 4
0 4
90
90
mV
mV
mV
µ
mV
µ
s x
s x
+
+
+
+
1 5 3 0
90
1 0 3 0
90
150
150
. / .
. / .
mV
mV
mV
mV
=
=
µ
µ
s
s
4 96
4 07
.
.






V
V