LM5025AEVAL National Semiconductor, LM5025AEVAL Datasheet - Page 12

• Manufacturer Part Number: LM5025AEVAL
• Description: BOARD EVALUATION LM5025A
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM5025AEVAL

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 3.3V
• Current - Output: 30A
• Voltage - Input: 36 ~ 72V
• Regulator Topology: Buck
• Frequency - Switching: 230kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM5025A
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -

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Soft-Start
The softstart feature allows the power converter to gradually
reach the initial steady state operating point, thus reducing
start-up stresses and surges. At power on, a 20µA current is
sourced out of the softstart pin (SS) into an external capacitor.
The capacitor voltage will ramp up slowly and will limit the
COMP pin voltage and therefore the PWM duty cycle. In the
event of a fault as determined by V
dervoltage (UVLO) or second level current limit, the output
gate drivers are disabled and the softstart capacitor is fully
discharged. When the fault condition is no longer present a
softstart sequence will be initiated. Following a second level
current limit detection (CS2), the softstart current source is
reduced to 1µA until the first output pulse is generated by the
PWM comparator. The current source returns to the nominal
20µA level after the first output pulse (~1V at the SS pin).
CC
undervoltage, line un-
12
Thermal Protection
Internal Thermal Shutdown circuitry is provided to protect the
integrated circuit in the event the maximum junction temper-
ature is exceeded. When activated, typically at 165°C, the
controller is forced into a low power standby state with the
output drivers and the bias regulator disabled. The device will
restart after the thermal hysteresis (typically 25°C). During a
restart after thermal shutdown, the softstart capacitor will be
fully discharged and then charged in the low current mode
(1µA) similar to a second level current limit event. The thermal
protection feature is provided to prevent catastrophic failures
from accidental device overheating.