AN1732 Rev.1.00
Page 2 of 13
December 6, 2016
ISL70002SEHEVAL1Z
Quick Start
1. Toggle S1 to the down (OFF) position.
2. Turn on the power supply. Set the output voltage to 3.3V and
set the output current limit to 20A. Turn off the power supply.
3. Connect the positive lead of the power supply to J1 and the
negative lead of the power supply to J2.
4. Turn on the electronic load and set the output current to 6A.
5. Connect the positive lead of the electronic load to J39 and
connect the negative lead of the electronic load to J40.
6. Configure one DMM to monitor the input voltage from TP7 to
TP11.
7. Configure another DMM to monitor the output voltage from
TP13 to TP11.
8. Connect Channel 1 of the oscilloscope to J6 (or from TP33 to
TP28) to monitor the rectangular waveform on the LXx pins.
9. Connect Channel 2 of the oscilloscope to J14 (or from TP36 to
TP37) to monitor the output voltage. Ripple voltage is
customarily measured with 20MHz bandwidth limiting.
10. Toggle S1 to the up (ON) position.
11. Verify the output voltage is 1.0V ±3% and the frequency of the
LXx waveform is 1MHz ±10%.
Layout Guidelines
1. Use an eight-layer PCB with 2 ounce (70µm) copper or
equivalent in thinner layers.
2. Two layers should be dedicated for ground plane.
3. Top and bottom layers should be used primarily for signals,
but can also be used to increase the VIN, VOUT, and ground
planes as required.
4. Connect all AGND, DGND, and PGNDx pins directly to the
ground plane. Connect all PVINx pins directly to the VIN
portion of the power plane.
5. Locate ceramic bypass capacitors as close as possible to U1.
Prioritize the placement of the bypass capacitors on the pins
of U1 in the order shown: PVINx, REF, AVDD, DVDD, SS, EN,
PGOOD.
6. Locate the output voltage resistive divider as close as
possible to the FB pin of the IC. The top leg of the divider
should connect directly to the load and the bottom leg of the
resistive divider should connect directly to AGND. The junction
of the resistive divider should connect directly to the FB pin.
7. Use a small island of copper to connect the LXx pins of U1 to
the inductor(s), L1 and L2, to minimize the routing
capacitance that degrades efficiency. Separate the island
from ground and power planes as much as possible.
8. Keep all signal traces as short as possible.
9. A small series snubber (R
25
and C
20
) connected from the LXx
pins to the PGNDx pins may be used to dampen ringing on the
LXx pins if desired.
10. For optimum thermal performance, place a pattern of vias on
the top layer of the PCB directly underneath U1. Connect the
vias to the ground planes, which serve as a heatsink. Thermal
interface material such as a Sil-Pad should be used to fill the
gap between the vias and the bottom of U1 to ensure good
thermal contact. Using a Sil-Pad has the added benefit of
raising the bottom of U1 from the PCB surface so that a slight
bend can be added to the leads for strain relief.
