EN5366QI Evaluation Board Application Note
November 2006 V_1
Enpirion EN5366QI 6A DCDC Converter
w/Integrated Inductor Evaluation Board
Introduction
Congratulations! You are evaluating a complete power system on silicon:
•
The EN5366QI features integrated inductor, power MOSFETS, Gate
Drive, Compensation Network, and controller and protection circuitry. This
level of integration delivers a substantial reduction in footprint and part
count over competing solutions.
The EN5366QI features resistor divider output voltage programming. The
resistor divider allows the user to set the output voltage to any value within
the range 0.8V to (V
IN
-V
DROPOUT
). The evaluation board utilizes a small
trim pot to adjust the output voltage There is also a footprint for a fixed
0805 sized resistor to replace the trim pot.
The user can also program the Over-Voltage-Protection (OVP) trip level
using a separate resistor divider. The board does NOT come with the
OVP resistors populated
The input capacitor is a 10V rated 47uF X5R MLCC. The output filter
section is populated with 5 x 10uF 6.3V rated X5R MLC capacitors to
achieve the required ~50uF of output capacitance. The combination of 5 x
10uF caps yields a very low ESR and hence low output ripple. A single
47uF capacitor can be substituted if a minimum footprint configuration is
desired. The Soft-start capacitor is a small 10V rated 15nF X5R MLCC.
Pads are available to add up to one additional input capacitor and there
are a total of 5 pads to accommodate the output capacitor(s). This allows
for evaluation of performance over a wide range of input/output capacitor
combinations.
Easy jumpers are provided for the following signals:
o
Enable
Numerous test points are provided as well as banana plugs for input and
output connections
The board comes with input decoupling and reverse polarity protection to
protect the device from common setup mishaps.
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EN5366QI Evaluation Board Application Note
November 2006 V_1
Quick Start Guide
Figure 1 shows a top view of the evaluation board.
WARNING:
complete steps 1 through 4 before
applying power to the EN5366QI evaluation
board.
STEP 1: Set the “ENABLE” jumper to the Disable
Position.
STEP 2: Connect Power Supply to the input power connectors, VIN (+) and
GND (-) as indicated in Figure 1.
CAUTION:
be mindful of the polarity. Even though the evaluation board
comes with reverse polarity protection diodes, it is rarely a good idea to
reverse the input polarity.
STEP 3: Connect the load to the output connectors VOUT (+) and GND (-), as
indicated in Figure 1.
Jumper set
to “disable”
STEP 4: Apply V
IN
to the board and move the ENABLE jumper to the enabled
position. The EN5366QI is now powered up!
NOTE:
There is no de-bouncing circuitry associate with the enable pin.
NOTE:
The trim pot is set at the factory to a predetermined output voltage.
To adjust to another output voltage setting, turn the screw on the trim pot
while monitoring the output voltage using an accurate volt-meter.
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EN5366QI Evaluation Board Application Note
November 2006 V_1
Output
Enable
Output Voltage
Select Trim Pot.
V
OUT
(+)
V
IN
(+)
Decoupling Cap
(to decouple supply cables)
Reverse polarity
protection diodes
GND (-)
GND (-)
COUT = 5 x 10uF 1206
Figure 1. Evaluation Board Layout.
C
IN
1210 47uF
Output Voltage Select
Programming Output Voltage and OVP
The EN5366QI output voltage is programmed using a simple resistor divider
network. Figure 2 shows a schematic view of the resistor divider configuration.
The evaluation board uses a trim pot in place of resistor Ra1.
The EN5366QI output voltage and over voltage thresholds are determined by the
voltages presented at the XFB and XOV pins respectively. These voltages are
set by way of resistor dividers between V
OUT
and AGND with the midpoint going
to XFB and XOV.
It is recommended that Rb1 and Rb2 resistor values be ~2kΩ. Use the following
equation to set the resistor Ra1 for the desired output voltage:
Page 3 of 5
EN5366QI Evaluation Board Application Note
November 2006 V_1
Ra
1
=
(
Vout
−
0.75
V
) *
Rb
1
0.75
V
If over-voltage protection is desired, use the following equation to set the resistor
Ra2 for the desired OVP trip-point. Note that the evaluation board leaves these
resistors un-populated.
Ra
2
=
(
OVPtrip
−
0.90
V
) *
Rb
2
0.90
V
By design, if both resistor dividers are the same, the OV trip-point will be 20%
above the nominal output voltage.
V
IN
PVIN
POK
VOUT
V
OUT
R
a2
R
a1
~50uF
47µF
AVIN
XOV
SS
XFB
AGND
PGND
C
SS
R
b2
R
b1
Figure 2.
V
OUT
and OVP resistor divider networks.
NOTE:
if no OVP divider is present, there will be no over-voltage protection and POK will remain
“high” as long as V
OUT
remains above 90% of the nominal V
OUT
setting.
Test Recommendations
Recommendations
To guarantee measurement accuracy, the following precautions should be
observed:
1. Make all input and output voltage measurements at the board using the
test points provided. This will eliminate voltage drop across the line and
load cables that can produce false readings.
2. Measure input and output current with series ammeters or accurate
shunt resistors. This is especially important when measuring efficiency.
3. Use a balanced impedance probe tip to measure switching signals to
avoid noise coupling into the probe ground lead.
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EN5366QI Evaluation Board Application Note
November 2006 V_1
Input and Output Capacitors
The
input
capacitance requirement is 47uF for the EN5366QI. Enpirion
recommends that a low ESR MLC capacitor be used. The voltage rating should
rated high enough to provide adequate margin for your application. There is a
pre-tinned pad for one additional 1210 capacitor to experiment with input filter
performance.
The
output
capacitance requirement is approximately 50uF of capacitance. The
EN5366QI-E evaluation board comes populated with 5 x 10uF 6.3V 1206 MLC
capacitors. The 5 parallel capacitors provide for reduced ESR and hence lower
output ripple voltage. If a minimum footprint configuration is desired, the 5 x10uF
capacitors can be replaced with a single 47uF MLC capacitor.
NOTE:
Capacitors must be X5R or X7R dielectric formulations.
NOTE:
Please refer to product datasheet for specific recommendations.
Contact Information
Enpirion, Inc.
685 Route 202/206
Suite 305
Bridgewater, NJ 08807
Phone: 908-575-7550
Fax: 908-575-0775
Enpirion reserves the right to make changes in circuit design and/or
specifications at any time without notice. Information furnished by Enpirion is
believed to be accurate and reliable. Enpirion assumes no responsibility for its
use or for infringement of patents or other third party rights, which may result
from its use. Enpirion products are not authorized for use in nuclear control
systems, as critical components in life support systems or equipment used in
hazardous environment without the express written authority from Enpirion.
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