ISL6401EVAL1 Intersil, ISL6401EVAL1 Datasheet - Page 2

• Manufacturer Part Number: ISL6401EVAL1
• Description: EVALUATION BOARD ISL6401
• Manufacturer: Intersil

Specifications of ISL6401EVAL1

• Main Purpose: DC/DC, Negative Inverter
• Outputs And Type: 2, Isolated
• Power - Output: 11.5W
• Voltage - Output: -24V, -72V
• Current - Output: 120mA, 120mA
• Voltage - Input: 5V, 12V
• Regulator Topology: Inverting
• Board Type: Fully Populated
• Utilized Ic / Part: ISL6401
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Using the ISL6401EVAL1Z Evaluation Board
The ISL6401EVAL1Z Schematic shows a current mode
power supply using the Intersil ISL6401 in standard flyback
topology. The ISL6401EVAL1Z evaluation board is shipped
“ready to use” right from the box. The IC requires +5V Bias.
The evaluation board input voltage can be 10V to 16V with
the specified transformer and external components. The
output voltages are -24V at 120mA and -72V at 120mA. The
board is capable of evaluating device operation with loads
that simulate one, two, three or four line operation. The use
of an electronic load enables evaluation over a wide range of
operating conditions. Simply vary the load on each output
from 0mA to 120mA in any combination to match exact
application requirements. The circuit uses off-the-shelf
inexpensive transformers to generate both outputs using a
single controller. The transformer turns ration is 1:1:1:1
where 24V appear across each secondary winding and the
primary during the switch off-time. The remaining secondary
windings are stacked in series to develop -48V. The -48V
section is then stacked on the -24V section to get the -72V.
This technique provides good cross regulation, lowers the
voltage rating required for the output capacitors and lowers
the RMS current, allowing the use of cheaper output
capacitors. Also, the selection of a transformer with multifilar
winding lowers the leakage inductance and cost. The cross
regulation of both output is achieved by using split feedback
for both outputs where the feedback factor can be weighed
based on load condition on both outputs.
The evaluation board kit also includes 5 samples of
ISL6401CBZ and ISL6401CRZ each.
Recommended Test Equipment
• A 5V power supply to bias the IC.
• A 12V power supply capable of supplying 2A of current
• Two electronic loads
• Precision digital multimeters
• A 4-channel scope with probes
Power and Load Connections
The ISL6401EVAL1Z evaluation board has three sets of
terminal posts and a jumper that are used to supply the input
voltages and to monitor and load the outputs.
Jumper Settings - Jumper JP1 allows the ISL6401 to be
biased from a separate 5V supply or from the input voltage
at VIN using a zener diode.
ISL6401EVAL1Z
BOARD NAME
TABLE 2. ISL6401EVAL1Z EVALUATION BOARD
ISL6401CBZ
2
IC
14 Ld SOIC
PACKAGE
Application Note 1082
If a 5V supply is being used for the VCC input, place a
jumper connecting the pins to the left (pin 1 and pin 2) of
JP1. Placing a jumper to the right (pin 2 and pin 3) of JP2 will
supply the bias of the ISL6401 from the input voltage at VIN
using a zener diode (D1).
Input Voltage - Adjust the power supplies to provide the 5V
and 12V input voltages. With the power supplies turned off,
connect the positive lead of the 5V supply to the VCC post
(P3). Connect the ground lead of the supply to the GND post
(P4). Connect the positive lead of the 12V supply to the VIN
post (P1). Connect the ground lead to the GND post (P2).
Output Voltage Loading and Monitoring - To exercise
and monitor VOUT1, connect the positive lead of one of the
electronic loads to the GND post (P7). Connect the ground
lead of the electronic load to the VOUT1 post (P8). Connect
the positive end of a digital multimeter to the VOUT1 post
(P8). Connect the digital multimeter ground terminal to the
GND post (P7).
To exercise and monitor VOUT2, connect the positive lead of
the other electronic load to the GND post (P10). Connect the
ground lead of the electronic load to the VOUT1 post (P9).
Connect the positive end of a digital multimeter to the
VOUT1 post (P9). Connect the digital multimeter ground
terminal to the GND post (P10).
Each output can be viewed with an oscilloscope using the
two scope probes, SP1 (VOUT1) and SP2 (VOUT2).
Start-up
The ISL6401 features an internal digital soft-start to reduce
transformer and output capacitor stress and to reduce the
inrush current surge on the input circuits. Figure 1 shows the
start-up sequence.
VOUT1
20V/DIV
VIN
10V/DIV
VOUT2
20V/DIV
FIGURE 1. SOFT-START WAVEFORMS (2ms/DIV)
10ms/DIV
January 30, 2009
AN1082.2