MAX17595EVKIT# Maxim Integrated, MAX17595EVKIT# Datasheet - Page 12

• Manufacturer Part Number: MAX17595EVKIT#
• Description: Power Management IC Development Tools MAX17595 Eval Kit
• Manufacturer: Maxim Integrated

Specifications of MAX17595EVKIT#

• Rohs: yes

The devices offer a built-in gate driver for driving an
external n-channel MOSFET. The NDRV pin can source/
sink peak currents in excess of 900mA/1500mA.
The MAX17595/MAX17596 operate at a maximum duty
cycle of 49%. The MAX17597 offers a maximum duty
cycle of 94% to implement flyback and boost converters
involving large input-to-output voltage ratios in DC-DC
applications. Slope compensation is necessary for sta-
ble operation of peak-current-mode controlled convert-
ers such as the MAX17595/MAX17596/MAX17597, in
addition to the loop compensation required for small
signal stability. The MAX17595/MAX17596/MAX17597
implement a SLOPE pin for this purpose. See the
Compensation
The devices implement soft-start operation for the fly-
back/boost regulators. A capacitor connected to the SS
pin programs the soft-start period. The soft-start feature
reduces input inrush current during startup. When the
voltage on the SLOPE pin is more than 0.2V, the refer-
ence to the internal error amplifier is ramped up from
0V to 1.21V in a linear manner, as programmed by the
soft-start capacitor. See the
(SS) section.
The ICs’ switching frequency is programmable between
100kHz and 1MHz with resistor R
RT and SGND. Use the following formula to determine the
appropriate value of R
output-switching frequency (f
where f
The switching frequency of the converter can be
dithered in a range of Q10% by connecting a capaci-
tor from DITHER/SYNC to SGND, and a resistor from
DITHER to RT. Spread-spectrum modulation technique
spreads the energy of switching frequency and its har-
monics over a wider band while reducing their peaks,
helping to meet stringent EMI goals.
Maxim Integrated
Spread-Spectrum Applications (Low EMI)
n-Channel MOSFET Gate Driver (NDRV)
SW
Switching Frequency Selection (RT)
is the desired switching frequency.
section for more details.
R
RT
RT
needed to generate the desired
Frequency Dithering for
=
Programming Soft-Start (SS)
10
SW
f
Maximum Duty Cycle
SW
10
):
RT
connected between
Soft-Start (SS)
Peak-Current-Mode Controllers for
MAX17595/MAX17596/MAX17597
Flyback and Boost Regulators
Slope
The devices’ EN/UVLO pin serves as an enable/disable
input, as well as an accurate programmable input UVLO
pin. The devices do not commence startup operation
unless the EN/UVLO pin voltage exceeds 1.21V (typ).
The devices turn off if the EN/UVLO pin voltage falls
below 1.15V (typ). A resistor-divider from the input DC
bus to ground can be used to divide down and apply a
fraction of the input DC voltage (V
pin. The values of the resistor-divider can be selected so
the EN/UVLO pin voltage exceeds the 1.23V (typ) turn-
on threshold at the desired input DC bus voltage. The
same resistor-divider can be modified with an additional
resistor (R
tion in addition to the EN/UVLO functionality as shown
in
1.21V (typ), the devices stop switching and resume
switching opera tions only if voltage at the OVI pin falls
below 1.15V (typ). For given values of startup DC input
voltage (V
voltage (V
be calculated as fol lows, assuming a 24.9kI resistor
for R
where R
where R
In universal AC input applications, R
implemented as equal resistors in series (R
and R
to its maximum operation voltage.
For low-voltage DC-DC applications based on the
MAX17596/MAX17597, a single resistor can be used in
the place of R
mately 40V.
Figure
OVI
DC
Startup Voltage and Input Overvoltage
:
OVI
EN
R
) so that voltage across each resistor is limited
SUM
OVI
OVI
2. When voltage at the OVI pin exceeds
R
=
START
and
Protection Setting (EN /UVLO, OVI)
is in kI, while V
DC1
R
) to implement input overvoltage protec-
), the resistor values for the divider can
EN
SUM
=
Applications Information


R
R
) and input overvoltage-protection
= ×
OVI
R
OVI
, as the voltage across it is approxi-
=
R
DC2
OVI
are in kI, while V
+
R
EN
R



=
V
START
DC3
 

START
V
×
OVI


V
START
1.21
and V
R
DC
SUM
−
SUM
3
1 k
) to the EN/UVLO



START
OVI
−
may need to be
I
k
1 k
I



are in volts.
DC1
I
is in volts.
, R
DC2
12
,