MAX17082GTL+ Maxim Integrated Products, MAX17082GTL+ Datasheet - Page 27

• 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

The MAX17021/MAX17082/MAX17482 integrate the dif-
ference between the current-sense voltages and adjust
the on-time of the secondary phase to maintain current
balance. The current balance now relies on the accura-
cy of the current-sense resistors instead of the inaccu-
rate, thermally sensitive on-resistance of the low-side
MOSFETs. With active current balancing, the current mis-
match is determined by the current-sense resistor values
and the offset voltage of the transconductance amplifiers:
where R
the current-sense pins and V
ance
Characteristics table.
The worst-case current mismatch occurs immediately
after a load transient due to inductor value mismatches
resulting in different di/dt for the two phases. The time it
takes the current-balance loop to correct the transient
imbalance depends on the mismatch between the
inductor values and switching frequency.
The current-limit circuit employs a unique “valley” cur-
rent-sensing algorithm that uses current-sense resistors
between the current-sense inputs (CSP_ to CSN_) as
the current-sensing elements. If the current-sense sig-
nal of the selected phase is above the current-limit
threshold, the PWM controller does not initiate a new
cycle until the inductor current of the selected phase
drops below the valley current-limit threshold. When
either phase trips the current limit, both phases are
effectively current limited since the interleaved con-
troller does not initiate a cycle with either phase.
Since only the valley current is actively limited, the actu-
al peak current is greater than the current-limit thresh-
old by an amount equal to the inductor ripple current.
Therefore, the exact current-limit characteristic and
maximum load capability are a function of the current-
sense resistance, inductor value, and battery voltage.
When combined with the undervoltage-protection cir-
offset
SENSE
I
IMVP-6+/IMVP-6.5 CPU Core Power Supplies
OS IBAL
(
is the effective sense resistance seen at
specification
)
______________________________________________________________________________________
=
I
LMAIN LSEC
Dual-Phase, Quick-PWM Controllers for
-
I
OS(IBAL)
=
in
V
R
OS IBAL
is the current-bal-
SENSE
Current Balance
the
(
Current Limit
)
Electrical
cuit, this current-limit method is effective in almost
every circumstance.
The positive valley current-limit threshold voltage at
CSP_ to CSN_ equals precisely 1/10 of the differential
TIME to ILIM voltage over a 0.1V to 0.5V range (10mV
to 50mV current-sense range). Connect ILIM directly to
V
22.5mV (typ).
The negative current-limit threshold (forced-PWM mode
only) is nominally -125% of the corresponding valley
current-limit threshold. When the inductor current drops
below the negative current limit, the controller immedi-
ately activates an on-time pulse—DL_ turns off, and
DH_ turns on—allowing the inductor current to remain
above the negative-current threshold.
Carefully observe the PCB layout guidelines to ensure
that noise and DC errors do not corrupt the current-sense
signals seen by the current-sense inputs (CSP_, CSN_).
The MAX17021/MAX17082/MAX17482 include a
transconductance amplifier for adding gain to the volt-
age-positioning sense path. The amplifier’s input is gen-
erated by summing the current-sense inputs, which
differentially sense the voltage across either current-
sense resistors or the inductor’s DCR. The amplifier’s
output connects directly to the regulator’s voltage-posi-
tioned feedback input (FB), so the resistance between
FB and the output-voltage sense point determines the
voltage-positioning gain:
where the target voltage (V
Nominal Output-Voltage Selection section, and the FB
amplifier’s output current (I
sum of the current-sense voltages:
where V
sense voltage, and G
defined in the Electrical Characteristics table.
CC
Voltage-Positioning Amplifier (Steady-State Droop)
to set the default current-limit threshold setting of
CS
= V
Feedback Adjustment Amplifiers
V
CSP_
OUT
I
FB
=
= V
- V
G
m FB
CSN_
TARGET
(
m(FB)
)
η
X
TARGET
FB
∑
PH
=
is the differential current-
1
) is determined by the
is typically 600μS as
V
- R
CSX
FB
) is defined in the
|
FB
27