MAX15034BEVKIT+ Maxim Integrated Products, MAX15034BEVKIT+ Datasheet - Page 23

• 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

The MAX15034 limits the reverse current when the out-
put capacitor voltage is higher than the preset output
voltage. Calculate the maximum reverse current limit
based on V
R
The output voltage is set by the combination of resistors
R1, R2, and R
Amplifier section. First select a value for resistor R2. Then
calculate the value of R1 from the following equation:
where V
value of R
where ΔV
load to full load. R
is R5 and R7 in Figure 6.
The MAX15034 uses an average current-mode control
scheme to regulate the output voltage (see Figure 2).
The main control loop consists of an inner current loop
and an outer voltage loop. The voltage error amplifier
(VEA1 and VEA2) provides the controlling voltage for
the current loop in each phase. The output inductor is
hidden inside the inner current loop. This simplifies the
design of the outer voltage control loop and also
improves the power-supply dynamics. The objective of
the inner current loop is to control the average inductor
current. The gain-bandwidth characteristic of the cur-
rent loop can be tailored for optimum performance by
the compensation network at the output of the current-
error amplifier (CEA1 or CEA2). Compared with peak
current-mode control, the current-loop gain crossover
frequency, f
but the gain at low frequencies is much higher. This
results in the following advantages over peak current-
mode control.
Configurable, Single-/Dual-Output, Synchronous
SENSE
Buck Controller for High-Current Applications
.
OUT(NL)
OUT
F
from the following equation:
C
CLMP_LO
R
R
, can be made approximately the same,
F
is the allowable drop in voltage from no
1
F
=
I
=
is the voltage at no load. Then find the
REVERSE
(
as described in the Voltage-Error
I
F
______________________________________________________________________________________
V
OUT
OUT NL
is R8 and R9, R1 is R4 and R6, R2
and the current-sense resistor
×
(
0 6125
R
.
Output-Voltage Setting
=
SENSE
)
Δ
Reverse Current Limit
1 55 10
−
V
.
R
OUT
0 6125
.
SENSE
×
×
36
)
−
Compensation
3
×
×
R
R
2
1
1) The average current tracks the programmed cur-
2) Slope compensation is not required, but there is a
3) Noise immunity is excellent.
4) The average current-mode method can be used to
For stability of the current loop, the amplified inductor-
current downslope at the negative input of the PWM
comparator (CPWM1 and CPWM2) must not exceed
the ramp slope at the comparator’s positive input. This
puts an upper limit on the current-error amplifier gain at
the switching frequency. The inductor current downs-
lope is given by V
inductor (L1 and L2 in Figure 6) and V
voltage. The amplified inductor current downslope at
the negative input of the PWM comparator is given by:
where R
in Figure 6) and g
amplifier (CEA_) at the switching frequency. The slope
of the ramp at the positive input of the PWM comparator
is 2V x f
maximum value of R
The highest crossover frequency f
or alternatively:
Equation (1) can now be rewritten as:
rent with a high degree of accuracy.
limit to the loop gain at the switching frequency to
achieve stability.
sense and control the current in any circuit branch.
SENSE
SW
R
R
Δ
f
CF
SW
Δ
CF
V
. Use the following equation to calculate the
t
L
f
CMAX
≤
=
=
=
is the current-sense resistor (R1 and R2
V
f
V
V
OUT
CMAX
IN
OUT
M
L
OUT
=
x R
CF
×
π
×
2π
R
f
×
×
SW
2
R
×
S
CF
(R14 or R15 in Figure 6).
f
/L where L is the value of the
V
R
C
SENSE
×
×
2π
IN
× ×
SENSE
f
is the gain of the current-error
×
V
×
SW
9
OUT
×
L
V
IN
V
g
×
OUT
×
m
L
×
36
36
CMAX
×
×
g
2 ( )
OUT
g
m
m
is given by:
×
is the output
R
1 ( )
CF
23