MAX15041EVKIT+ Maxim Integrated Products, MAX15041EVKIT+ Datasheet - Page 11

• Manufacturer Part Number: MAX15041EVKIT+
• Description: KIT EVAL MAX15041ETE
• Manufacturer: Maxim Integrated Products
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of MAX15041EVKIT+

• Board Size: 55 mm x 55 mm
• Operating Supply Voltage: 4.5 V to 28 V
• Product: Power Management Development Tools
• Dimensions: 55 mm x 55 mm
• Silicon Manufacturer: Maxim
• Silicon Core Number: MAX15041
• Kit Application Type: Power Management
• Application Sub Type: Synchronous Buck Converter
• Kit Contents: Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: MAX15041

The MAX15041 utilizes a soft-start feature to slowly ramp
up the regulated output voltage to reduce input inrush
current during startup. Connect a capacitor from SS to
SGND to set the startup time (see the Setting the Soft-
Start Time section for capacitor selection details ) .
The MAX15041 has an internal 5.1V (typ) LDO. V
externally compensated with a minimum 1µF, low-ESR
ceramic capacitor. The V
the low-side MOSFET driver, and to supply the internal
control logic. When the input supply (IN) is below 4.5V,
V
rent limit is 80mA (typ) and an UVLO circuit inhibits
switching when V
A high-gain error amplifier provides accuracy for the volt-
age feedback loop regulation. Connect the necessary
compensation network between COMP and SGND (see
the Compensation Design Guidelines section). The error-
amplifier transconductance is 1.6mS (typ). COMP clamp
low is set to 0.68V (typ), just below the PWM ramp com-
pensation valley, helping COMP to rapidly return to cor-
rect set point during load and line transients.
The PWM comparator compares COMP voltage to the
current-derived ramp waveform (LX current to COMP volt-
age transconductance value is 9A/V, typ.). To avoid insta-
bility due to subharmonic oscillations when the duty cycle
is around 50% or higher, a compensation ramp is added
to the current-derived ramp waveform. The compensation
ramp slope (0.45V x 350kHz) is equivalent to half of the
inductor current down slope in the worst case (load 3A,
current ripple 30% and maximum duty cycle operation of
90%). Compensation ramp valley is set at 0.83V (typ).
When the converter output is shorted or the device is
overloaded, the high-side MOSFET current-limit event
(6A, typ) turns off the high-side MOSFET and turns on
the low-side MOSFET. In addition, it discharges the SS
Step-Down DC-DC Regulator with Internal Switches
DD
is 50mV (typ) lower than IN. The V
Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
DD
Programmable Soft-Start (SS)
______________________________________________________________________________________
falls below 3.85V (typ).
DD
Overcurrent Protection
voltage is used to supply
Internal LDO (V
PWM Comparator
and Hiccup Mode
Error Amplifier
DD
output cur-
DD
DD
is
)
capacitor, C
typ). If the overcurrent condition persists, SS is pulled
below 0.606V and a hiccup event is triggered.
During a hiccup event, high-side and low-side
MOSFETs are kept off, and COMP is pulled low for a
period equal to 16 times the nominal soft-start time
(blanking time). This is obtained by charging SS from 0
to 0.606V with a 5µA (typ) current, and then slowly dis-
charging it back to 0V with a 333nA (typ) current. After
the blanking time has elapsed, the device attempts to
restart. If the overcurrent fault has cleared, the device
resumes normal operation, otherwise a new hiccup
event is triggered (see the Output Short-Circuit
Waveforms in the Typical Operating Characteristics ).
The MAX15041 contains an internal thermal sensor that
limits the total power dissipation in the device and pro-
tects it in the event of an extended thermal fault condi-
tion. When the die temperature exceeds +155°C (typ),
the thermal sensor shuts down the device, turning off
the DC-DC converter and the LDO regulator to allow
the die to cool. After the die temperature falls by 20°C
(typ), the device restarts, using the soft-start sequence.
Connect a resistive divider (R
and 3) from OUT to FB to SGND to set the DC-DC con-
verter output voltage. Choose R
errors due to the FB input bias current do not affect the
output-voltage precision. With lower value resistors, the
DC error is reduced, but the amount of power consumed
in the resistive divider increases. A typical tradeoff value
for R
acceptable. Once R
where the feedback threshold voltage V
(typ).
2
is 10kΩ, but values between 5kΩ and 50kΩ are
SS
Applications Information
for a fixed period of time ( T
Thermal-Shutdown Protection
R
1
2
Setting the Output Voltage
is chosen, calculate R
R
2
V
V
OUT
1
FB
1
and R
and R
1
2
2
, see Figures 1
so that the DC
FB
1
using:
0
= 0.606V
= 70ns,
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