MAX17009GTL+T Maxim Integrated Products, MAX17009GTL+T Datasheet - Page 37

• Manufacturer Part Number: MAX17009GTL+T
• Description: IC CTLR VIDEO SERIAL DUAL 40TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX17009GTL+T

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When using low-capacity ceramic-filter capacitors,
capacitor size is usually determined by the capacity
needed to prevent V
load transients. Generally, once enough capacitance is
added to meet the overshoot requirement, undershoot at
the rising load edge is no longer a problem.
The input capacitor must meet the ripple-current
requirement (I
For a dual, 180° interleaved controller, the out-of-phase
operation reduces the RMS input ripple current, effec-
tively lowering the input capacitance requirements.
When both outputs operate with a duty cycle less than
50% (V
defined by the following equation:
where I
In combined mode (GNDS2 = V
active, the input RMS current simplifies to:
For most applications, nontantalum chemistries (ceramic,
aluminum, or OS-CON) are preferred due to their resis-
tance to inrush surge currents typical of systems with a
mechanical switch or connector in series with the input.
If the MAX17009 is operated as the second stage of a
two-stage power-conversion system, tantalum input
capacitors are acceptable. In either configuration,
choose an input capacitor that exhibits less than 10°C
temperature rise at the RMS input current for optimal
circuit longevity.
Voltage positioning dynamically lowers the output volt-
age in response to the load current, reducing the out-
put capacitance and processor’s power-dissipation
requirements. The controller uses two transconduc-
tance amplifiers to set the transient and DC output-volt-
age droop (Figure 3). The transient-compensation
(TRC) amplifier determines how quickly the MAX17009
responds to the load transient. The FBDC_ amplifier
adjusts the steady-state regulation voltage as a func-
tion of the load. This adjustability allows flexibility in the
I
RMS
=
IN
IN
⎛
⎜
⎝
V
I
is the average input current:
IN
> 2 x V
OUT
I
V
RMS
IN
=
1
RMS
⎛
⎜
⎝
⎞
⎟
⎠
V
I
=
OUT OUT
OUT
V
I
OUT
OUT
IN
______________________________________________________________________________________
) imposed by the switching currents.
1
SOAR
(
1
I
), the RMS input-ripple current is
⎞
⎟
⎠
Input-Capacitor Selection
I
OUT
⎛
⎜
⎝
1
Voltage Positioning and
V
−
from causing problems during
OUT
V
I
IN
IN
1
+
)
Loop Compensation
+
⎛
⎜
⎝
⎞
⎟
⎠
⎛
⎜
⎝
V
⎛
⎜
⎝
DDIO
V
AMD Mobile Serial VID Dual-Phase
OUT
2
1
V
OUT
V
IN
IN
−
V
2
2
) with both phases
OUT
V
⎞
⎟
⎠
⎞
⎟
⎠
IN
I
I
OUT
OUT
⎞
⎟
⎠
2
2
(
I
OUT
2
−
Fixed-Frequency Controller
I
IN
)
selected current-sense resistor value or inductor DCR,
and allows smaller current-sense resistance to be
used, reducing the overall power dissipated.
Connect a resistor (R
remote-sense point to set the steady-state DC droop
(load line) based on the required voltage-positioning
slope (R
where R
G
Characteristics table, and R
current-sense resistor that is used to provide the
(CSP_, CSN_) current-sense voltage.
When the inductors’ DCR is used as the current-sense
element (R
should include an NTC thermistor to cancel the temper-
ature dependence of the inductor DCR, maintaining a
constant voltage-positioning slope.
Connect a resistor (R
remote-sense point to set the DC transient AC droop
(load-line) based on the required voltage-positioning
slope (R
where R
G
Characteristics table, and R
current-sense resistor that is used to provide the
(CSP_, CSN_) current-sense voltage.
When the inductors’ DCR is used as the current-sense
element (R
should include an NTC thermistor to cancel the temper-
ature dependence of the inductor DCR, maintaining a
constant voltage-positioning slope.
Most of the following MOSFET guidelines focus on the
challenge of obtaining high load-current capability
when using high-voltage (> 20V) AC adapters. Low-
current applications usually require less attention.
The high-side MOSFET (N
the resistive losses plus the switching losses at both
V
Ideally, the losses at V
losses at V
losses at V
at V
R
at V
IN(MIN)
DS(ON)
m(FBDC_)
m(FBAC_)
IN(MAX)
IN(MAX)
R
R
FBDC_
FBAC_
DROOPDC
DROOPAC
DROOPDC
but with higher C
DROOPAC
and V
IN(MIN)
, consider increasing the size of N
IN(MAX)
SENSE
is typically 1mS as defined in the Electrical
SENSE
is typically 1ms as defined in the Electrical
are significantly higher than the losses at
= R
= R
IN(MAX)
DROOPDC
DROOPAC
):
):
are significantly higher than the losses
, with lower losses in between. If the
= R
= R
is the desired steady-state droop,
is the desired steady-state droop,
Steady-State Voltage Positioning
IN(MIN)
FBDC_
FBAC_
Power-MOSFET Selection
DCR
DCR
. Calculate both these sums.
GATE
/ (R
/ (R
H
), the inductor DCR circuit
), the inductor DCR circuit
) must be able to dissipate
) between FBDC_ and the
) between FBAC_ and the
SENSE_
SENSE_
should be roughly equal to
SENSE_
SENSE_
). Conversely, if the losses
is the value of the
is the value of the
x G
x G
Transient Droop
m(FBDC_)
m(FBAC_)
H
(reducing
)
)
37