MAX15034BEVKIT+ Maxim Integrated Products, MAX15034BEVKIT+ Datasheet - Page 20

• Manufacturer Part Number: MAX15034BEVKIT+
• Description: KIT EVALUATION FOR MAX15034
• Manufacturer: Maxim Integrated Products

Specifications of MAX15034BEVKIT+

• Main Purpose: DC/DC, Step Down
• Voltage - Input: 5 ~ 28V
• Regulator Topology: Buck
• Board Type: Fully Populated
• Utilized Ic / Part: MAX15034
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Output: -
• Power - Output: -
• Frequency - Switching: -
• Outputs And Type: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
Keep the maximum output-voltage deviation less than
or equal to the adaptive voltage-positioning window
(ΔV
tion each from the output capacitance discharge and
the voltage drop across the ESR (ΔV
+ ΔV
the required ESR and capacitance value:
where I
t
Controller response time depends on the control-loop
bandwidth. C
The MAX15034 incorporates two forward current-limit
protection mechanisms, average current limit and hic-
cup fault current limit, which accurately limit the output
current per phase. The average current-mode control
technique of the MAX15034 accurately limits the maxi-
mum average output current per phase. The
MAX15034 senses the voltage across either a sense
resistor or can implement lossless inductor sense,
sensing the voltage across the parasitic resistance of
the inductor (DCR). Use either mechanism to limit the
maximum inductor current.
Table 2. Low-Side MOSFET Losses
Note: The gate drive losses are distributed between the drivers and the MOSFETs in the ratio of the gate driver’s resistance and the
MOSFET’s internal gate resistance.
20
Conduction Loss
Gate Drive Loss
RESPONSE
OUT
______________________________________________________________________________________
Q_OUT
LOSS
). During a load step, assume a 50% contribu-
LOAD_STEP
R
C
). Use the following equations to calculate
ESR OUT
OUT
is the response time of the controller.
OUT
_
=
is C6 and C7 in Figure 6.
Losses associated with MOSFET on-time, I
is a function of load current and duty cycle.
Losses associated with charging and
discharging the gate of the MOSFET every
cycle. There is no Q
MOSFET due to the zero-voltage turn-on. The
charge involved is (Q
I
LOAD STEP
is the step in load current and
=
I
Δ
LOAD STEP
_
V
ESR OUT
Δ
V
Q OUT
_
_
_
×
t
DESCRIPTION
RESPONSE
GD
OUT
G
Current Limit
charging involved in this
- Q
GD
= ΔV
).
ESR_OUT
RMS
The minimum average voltage, at which the voltage
across the current-sense resistor is clamped, is either
internally set to 20.4mV or is controlled by the voltage
at AVGLIMIT. The AVGLIMIT ground threshold of
550mV (typ) is the threshold above which the control of
the average current-limit voltage is transferred from the
internal 20.4mV (min) reference to the externally set
V
value, short AVGLIMIT to AGND. The minimum (inter-
nally set) average current limit is set at:
For example, the current-sense resistor:
for a maximum output current limit of 10A. A standard
value is 2mΩ. Also, adjust the value of the current-
sense resistor to compensate for parasitics associated
with the PCB. Select a noninductive resistor with an
appropriate wattage rating.
The implementation is shown in Figure 8.
When sensing directly across the inductor, connect an
RC circuit directly across the shunt or inductor (see
Figure 9).
AVGLIMIT
P
P
where I
GATEDRIVE
. For using the internal average current-limit
CONDUCTION
R
SENSE
RMS
I
LIMIT MIN
SEGMENT LOSSES
=
=
≈
(
V
20 4
=
DD
V
10
I
)
.
RMS
IN
=
×
A
mV
−
V
(
R
20 4
IN
Q
2
V
SENSE
OUT
G
=
×
.
R
mV
2 04
−
DS ON
.
Q
×
GD
(
m
I
LOAD
Ω
)
)
×
f
SW