MAX15035 Maxim Integrated Products, MAX15035 Datasheet - Page 19

• Manufacturer Part Number: MAX15035
• Description: 15A Step-Down Regulator
• Manufacturer: Maxim Integrated Products

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output voltage, connect an external pullup resistor
between PGOOD and V
works well in most applications. Figure 7 shows the
power-good and fault-protection circuitry.
When the internal feedback voltage rises 300mV above
the target voltage and OVP is enabled, the OVP compara-
tor immediately forces LX low, pulls PGOOD low, sets the
fault latch, and disables the SMPS controller. Toggle EN
or cycle V
latch and restart the controller.
When the feedback voltage drops 200mV below the
target voltage (REFIN), the controller immediately pulls
PGOOD low and triggers a 200µs one-shot timer. If the
feedback voltage remains below the undervoltage fault
threshold for the entire 200µs, the undervoltage fault
latch is set and the SMPS begins the shutdown
sequence. When the internal target voltage drops
below 0.1V, the MAX15035 forces a high impedance on
LX. Toggle EN or cycle V
clear the fault latch and restart the controller.
The MAX15035 features a thermal fault-protection cir-
cuit. When the junction temperature rises above
+160°C, a thermal sensor activates the fault latch, pulls
PGOOD low, shuts down the controller, and forces a
Figure 7. Power-Good and Fault Protection
15A Step-Down Regulator with Internal Switches
SOFT-START
CC
COMPLETE
POWER-GOOD AND FAULT PROTECTION
power below the V
EN
______________________________________________________________________________________
Thermal-Fault Protection (T
Undervoltage Protection (UVP)
Overvoltage Protection (OVP)
DD
CC
. A 100kΩ pullup resistor
power below V
CC
200µs
POR to clear the fault
SHOT
ONE-
IN
CLK
CC
OUT
- 200mV
TARGET
POR to
SHDN
)
high impedance on LX. Toggle EN or cycle V
below V
junction temperature cools by 15°C.
Firmly establish the input voltage range and maximum
load current before choosing a switching frequency and
inductor operating point (ripple-current ratio). The prima-
ry design trade-off lies in choosing a good switching fre-
quency and inductor operating point, and the following
four factors dictate the rest of the design:
•
•
Input Voltage Range: The maximum value
(V
supply voltage. The minimum value (V
account for the lowest input voltage after drops due
to connectors, fuses, and battery selector switches. If
there is a choice at all, lower input voltages result in
better efficiency.
Maximum load current: There are two values to
consider. The peak load current (I
determines the instantaneous component stresses
and filtering requirements, and thus drives output
capacitor selection, inductor saturation rating, and
the design of the current-limit circuit. The continu-
ous load current (I
stresses and thus drives the selection of input
capacitors, MOSFETs, and other critical heat-con-
tributing components.
(INMAX)
OVP
Quick-PWM Design Procedure
CC
+ 300mV
TARGET
POR to reactivate the controller after the
) must accommodate the worst-case input
FAULT
LATCH
LOAD
) determines the thermal
FB
OVP ENABLED
POWER-GOOD
FAULT
(INMIN)
LOAD(MAX)
CC
) must
power
19
)
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