ISL6310EVAL1Z Intersil, ISL6310EVAL1Z Datasheet - Page 6

• Manufacturer Part Number: ISL6310EVAL1Z
• Description: EVALUATION BOARD FOR ISL6310
• Manufacturer: Intersil

Specifications of ISL6310EVAL1Z

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 1.5V
• Current - Output: 60A
• Voltage - Input: 5 ~ 12V
• Regulator Topology: Buck
• Frequency - Switching: 400kHz
• Board Type: Fully Populated
• Utilized Ic / Part: ISL6310
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

Transient Response
The ISL6310EVAL1Z is designed without droop for a
maximum output load current of 60A. The Load step is
approximately 25A and the output voltage variation during
the transient is kept below 100mV peak to peak. This load
step have a maximum slew rate of approximately 50A/μs on
both the rising and falling edges. The on-board load
transient generator is designed to provide the specified load
step, different load steps and current slew rates can be
accommodated with the on Board Transient load generator.
The rising edge transient response of the ISL6310EVAL1Z, is
shown in Figure 8. In order to obtain the load current
waveform shown, the bench-top load is turned off, while the
on-board transient generator is pulsing a 25A step for 500μs.
When the load step occurs, the output capacitors provide the
initial output current, causing V
the ESR and ESL voltage drops in the capacitors. The
controller immediately responds to this drop by increasing
the PWM duty cycles to as much as 66%. The duty cycles
then decrease to stabilize V
At the end of the 500μs load pulse, the load current returns
to 0A. The transient response to this falling edge of the load
is shown in Figure 9. When the falling load step occurs, the
output capacitors must absorb the inductor current which
can not fall at the same rate of the load step. This causes
V
drops in the capacitors. The controller immediately responds
to this rise by decreasing the PWM duty cycles to zero, and
then increasing them accordingly to regulate VCORE to the
programmed 1.5V level.
GND>
OUT
FIGURE 8. ISL6310EVAL1Z RISING EDGE TRANSIENT LOAD
to rise suddenly due to the ESR and ESL voltage
V
RESPONSE
OUT
V(ILOAD)
OUT
5µs/DIV
6
OUT
.
to drop suddenly due to
Application Note 1197
Figure 10 shows both the rising and falling edges.
Overcurrent Protection
The ISL6310 is designed to stop all regulation and protect
the sensitive Load if an overcurrent event occurs. This is
done by continuously monitoring the total output current and
comparing it to an overcurrent trip level set by the OCSET
resistor, R11. If the output current ever exceeds the trip level
as shown in Figure 11 (at time T1), the ISL6310 immediately
turns the upper and lower MOSFETs off, causing V
fall to 0V. The controller holds the UGATE and LGATE
signals in this state for a period of 4096 switching cycles,
which at 400kHz is 10.25ms. The controller then re-initializes
the soft-start cycle (at time T2). If the load that caused the
overcurrent trip remains, another overcurrent trip will occur
before the soft-start cycle completes. The controller will
continue to try to cycle soft-start indefinitely until the load
current is reduced, or the controller is disabled. This
operation is shown in Figure 11.
GND>
GND>
FIGURE 9. ISL6310EVAL1Z FALLING EDGE TRANSIENT
FIGURE 10. ISL6310EVAL1Z TRANSIENT RESPONSE
V
V
RESPONSE
OUT
OUT
V(ILOAD)
V(ILOAD)
100µs/DIV
5µs/DIV
December 12, 2006
OUT
AN1197.1
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