ISL6420BEVAL1Z Intersil, ISL6420BEVAL1Z Datasheet - Page 4

• Manufacturer Part Number: ISL6420BEVAL1Z
• Description: EVAL BOARD 1 FOR ISL6420B
• Manufacturer: Intersil

Specifications of ISL6420BEVAL1Z

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A resistor, R
level. The PHASE node voltage is compared to the
voltage on the OCSET pin while the upper FET is on. A
current (100µA typically) is pulled from the OCSET pin to
establish this voltage across an external resistor. If
PHASE is lower than OCSET, while the upper FET is on,
then an overcurrent condition is detected for that clock
cycle. The pulse is immediately terminated, and a
counter is incremented. If an overcurrent condition is
detected for 8 consecutive clock cycles, and the circuit is
not in soft-start, the ISL6420B enters into hiccup mode.
During hiccup, the external capacitor on the ENSS pin is
discharged and soft-start is initiated. During soft-start,
pulse termination limiting is enabled, but the 8-cycle
hiccup counter is held in reset until soft-start is
completed.
The overcurrent function will trip at a peak inductor
current (I
where I
The OC trip point varies mainly due to the MOSFET’s
r
normal operating load range, calculate the R
resistor from Equation 1 using:
Determine ,
I
where ΔI is the output inductor ripple current. A small
ceramic capacitor should be placed in parallel with
R
presence of switching noise on the input voltage.
I
PEAK
1. The maximum r
2. The minimum I
DS(ON)
PEAK
OCSET
ENSS
V
I
temperature
specification table
OUT
OUT
for I
=
FIGURE 11. OVERCURRENT HICCUP MODE
OCSET
to smooth the voltage across R
I
-------------------------------------------------- -
variations. To avoid overcurrent tripping in the
OCSET
PEAK
PEAK
OCSET
R
DS ON
) determined by Equation 1:
>
is the internal OCSET current source.
•
I
OUT MAX
(
R
OCSET
(R8), programs the overcurrent trip
OCSET
)
DS(ON)
(
)
+
from the data sheet
(
4
ΔI
at the highest junction
) 2 ⁄
OCSET
Application Note 1504
OCSET
in the
(EQ. 1)
(EQ. 2)
The overcurrent trip point on the evaluation board has
been set to 16A.
Transient Performance
Figure 12, 13, and 14 show the response of the output
when subjected to transient loading from 0A to 10A at
1A/µs slew rate.
FIGURE 12. TRANSIENT RESPONSE
FIGURE 13. TRANSIENT RESPONSE
FIGURE 14. TRANSIENT RESPONSE
November 23, 2009
V
V
V
OUT
OUT
OUT
I
I
I
OUT
OUT
OUT
AN1504.0