LM5026EVAL National Semiconductor, LM5026EVAL Datasheet - Page 17

• Manufacturer Part Number: LM5026EVAL
• Description: BOARD EVALUATION LM5026
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM5026EVAL

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Isolated
• Voltage - Output: 3.3V
• Current - Output: 30A
• Voltage - Input: 36 ~ 78V
• Regulator Topology: Buck
• Frequency - Switching: 230kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM5026
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -

HICCUP MODE CURRENT LIMIT RESTART (RES)
The basic operation of the hiccup mode current limit restart is
described in the functional description. The delay time to
restart is programmed with the selection of the RES pin ca-
pacitor C
ous cycle-by-cycle current limit detection at the CS pin, the
time required for C
old is:
For example, if C
2.5 ms.
The cool down time, t2 is set by the soft-start capacitor (C
and the internal 1 µA SS current source, and is equal to:
RES
as illustrated in
RES
RES
= 0.01 µF the time t1 is approximately
to reach the 2.5V hiccup mode thresh-
Figure
FIGURE 16. Current Sense Using a Source Sense Resistor (R1)
FIGURE 15. Current Sense Using a Current Sense Transformer
7. In the case of continu-
SS
)
17
If C
The soft-start time t3 is set by the internal 50 µA current
source, and is equal to:
The time t2 provides a periodic cool-down time for the power
converter in the event of a sustained overload or short circuit.
This results in lower average input current and lower power
dissipated within the power components. It is recommended
that the ratio of t2/(t1 + t3) be in the range of 5 to 10 to make
SS
= 0.01 µF, t2 is
≈
20147926
20147927
14 ms.
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