ISL6558EVAL2 Intersil, ISL6558EVAL2 Datasheet - Page 7

• Manufacturer Part Number: ISL6558EVAL2
• Description: EVAL BOARD W/6605 DRVRS ISL6558
• Manufacturer: Intersil
• Series: Endura™r

Specifications of ISL6558EVAL2

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.35V
• Current - Output: 30A
• Voltage - Input: 4.5 ~ 5.5V
• Regulator Topology: Buck
• Frequency - Switching: 500kHz
• Board Type: Fully Populated
• Utilized Ic / Part: HIP6609, ISL6558
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

OVER CURRENT AND SHORT CIRCUIT
When the converter is momentarily shorted or overloaded,
as shown in Figure 13, the converter enters hiccup mode
with a narrow duty cycle and long switching period. PGOOD
stays low during the overcurrent period; it indicates the
output voltage is within regulation limits after the short is
removed and the output completes a soft-start interval.
As shown in Figure 14, the converter can sustain a
permanent short circuit remaining in hiccup mode with a
frequency of 185Hz. The average load current and the
average power dissipation in each power component are
reduced significantly; thus, the converter can stay at a short
without causing any permanent damage or thermal issues.
FIGURE 13. OVER-LOADED OUTPUT WAVEFORMS
FIGURE 14. SHORT-CIRCUIT WAVEFORMS
I
O
V
V
O
I
O
O
PGOOD
7
PGOOD
Application Note 1044
OVERVOLTAGE SHUTDOWN
With the COMP pin momentarily tied to a 4V voltage source
with respect to the ground, the error voltage jumps high and
the duty cycle increases. Thus, the output voltage rises up
immediately until it reaches the overvoltage threshold setting
the OV latch and triggers the PWM outputs low. PGOOD is
pulled low indicating output out of regulation, as shown in
Figure 15.
Conclusion
The superior performance of Intersil’s ISL6558 four-phase
controller, coupled with Intersil’s ISL6609 driver, has been
demonstrated in the low-profile reference design of a 40W,
500kHz interleaved DC/DC buck converter. An ultra high
efficiency of 90% at 1.35V output and 30A full load has been
achieved.
The extensive experimental results give users a better
understanding of the operation of the converter, the ISL6558
four-phase PWM controller, and the ISL6609 synchronous-
rectified driver.
FIGURE 15. OVERVOLTAGE WAVEFORMS
COMP
V
I
O
OUT
PGOOD
April 4, 2006
AN1044.2