Application Note EP5368QI Eval Board
May 2008 V1.0
Page 1 of 7
Enpirion Confidential
Enpirion EP5368QI DC/DC Converter
Module Evaluation Board
Introduction
This application note describes how to test the EP5368QI converter using the Enpirion
3x3 Module EVAL BOARD shown in Fig. 1. In addition to this document you will also
need the device datasheet.
The EP5368QI converter is part of a new class of DC/DC converter products, a complete
power system on silicon:
• This device is a complete module including magnetics, and requires only ceramic
input and output capacitors.
• The evaluation board is designed to offer a wide range of engineering evaluation
capabilities. This includes the base configuration of an 0603 input capacitor and
an 0805 output capacitor.
• Pads are available to add up to one additional input capacitor and up to two
additional output capacitors to allow for evaluation of performance over a wide
range of input/output capacitor combinations.
• Pads are available to populate an external resistor divider if desired.
• Easy jumpers are provided for the following signals:
o Enable
o VS0-VS2 output voltage select
• The following signals on the eval board are not used for the EP5368QI:
o Adaptive-biased light load mode (LLM)
o VS3 output voltage select pin
• Numerous test points are provided as well as clip leads for input and output
connections
• The board comes with input decoupling, and input reverse polarity protection to
safeguard the device from common setup mishaps.
Quick Start Guide
STEP 1: Set the “ENABLE” jumper to the Disable Position.
CAUTION: the signal pins, ENA, VS0, VS1, and VS2 must be
connected to a logic “high”, jump er to the left, or a logic “low”,
jumper to the right. If left floating the state is indeterminate.
STEP 2: Connect a power supply to the input test points, TP8 (+) and TP5 (-) as
indicated in Figure 1. The same test points can also be used to measure the input voltage.
Ou tput Disabled
Jumper
Application Note EP5368QI Eval Board
May 2008 V1.0
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Enpirion Confidential
CAUTION: be mindful of the polarity and the voltage magnitude. If VIN is
greater than the absolute maxim um rating in the datasheet, the board may get
damaged. If the input voltage polarity is wrong, diode D1 will conduct, and draw
excessive input current.
STEP 3: Set the output voltage select pins for the desired output voltage. Refer to Table
1 to determine the setting.
CAUTION: the external resistor divider is not populated in
the standard board configuration. Choosing the “EXT” option
for the EP5368QI without the external resistors R1 and R2
will result in unpredictable behavior.
STEP 4: Connect the load to the output connectors TP7 (+) and TP6 (-), as indicated in
Figure 1.The same test points are also used to measure the DC output voltage.
STEP 6: Move the ENABLE jumper to the enabled position, and power up the board.
The EP5368QI should now be operational.
Figure 1: Evaluation Board Layout. This board is used for multiple Enpirion 3x3 products.
Some of the functions are not supported in all of these products.
“0”
“1”
CIN
COUT
Decou pling Ca p
(to decouple supply cables)
Reverse polarity diode
Output Volta
g
e Select
Output Enable
Not supported
for EP5368QI
Not supported
for EP5368QI
Application Note EP5368QI Eval Board
May 2008 V1.0
Page 3 of 7
Enpirion Confidential
Output Voltage Select
Table 1. EP5368QI Output Voltage Select Truth Table
VS2 VS1 VS0 VOUT
0 0 0 3.3V
0 0 1 2.5V
0 1 0 1.8V
0 1 1 1.5V
1 0 0 1.25V
1 0 1 1.2V
1 1 0 0.8V
1 1 1 EXT
The EP5368QI utilizes a 3 pin output voltage select scheme. The output voltage is
programmed by setting the VSx jumpers to either a logic “1” or a logic “0” as described
in the Quick Start section
Table 1 shows the truth table for VOUT selection. There are seven preset output voltage
levels, and one option for external resistor programming.
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 as shown in Figure 2, and through-hole
test point pair TP2 to measure the output voltage ripple to avoid noise
coupling into the probe ground lead. Similarly, TP1 can be used to measure
input voltage ripple.
Figure 2: Balanced-impedance oscilloscope probe. Wrap bare wire around the
ground shaft and bring the wire close to the probe tip. This minimizes probe loop
inductance and stray noise pickup by the probe.
Application Note EP5368QI Eval Board
May 2008 V1.0
Page 4 of 7
Enpirion Confidential
Using The External Voltage Divider
The EP5368QI evaluation board is designed to provide a great deal of flexibility in
evaluating the performance of the Enpirion DC/DC module. The external voltage divider
option is chosen by setting the jumpers VS0 – VS2 to a logic “high”.
Pre-tinned pads are provided to place 0805 sized 1% resistors on the board to implement
an external resistor divider for choosing an output voltage other than one of the pre-set
voltages available on the VID. See Figure 3 for the basic circuit.
VIN
VSense
Vin
VS1
VS2
VS0
EP5368QI
Cout
Cin
VOUT
Vout
GND
ENABLE
R1
R2
VFB
Figure 3. External divider schematic for the EP5368QI.
The output voltage is selected by the following formula:
()
2
1
1603.0 R
R
OUT VV +=
R1 must be chosen as 200kΩ to maintain control loop stability. Then R2 is given as:
Ω
−
=603.0 1603.0
2OUT
VR
R
NOTE: Even though it is possible to run the EP5368QI up to 700mA using an
external voltage divider as outlined in the datasheet, this evaluation board is only
configured to run this part up to 600mA. Please contact Enpirion applications if
you would like to modify this board to push the output current up to 700mA.
Application Note EP5368QI Eval Board
May 2008 V1.0
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Enpirion Confidential
Dynamically Adjustable Output
The EP5368QI is designed to allow for dynamic switching between the predefined
voltage levels by toggling the VID pins. The inter-voltage slew rate is optimized to
prevent excess undershoot or overshoot as the output voltage levels transition. The slew
rate is defined in the datasheet.
This feature can be tested by connecting the VSx jumper center pins to logic drivers to
toggle between the various VOUT states.
Input and Output Capacitors
The input capacitance is a single 0603 X5R MLCC. Please see the datasheet for the exact
value. There are pre-tinned pads that allows for one additional 0603 capacitor to
experiment with input filter performance.
The output capacitance requirement is a single 0805 X5R MLCC. Please see the
datasheet for the exact value. The board has pre-tinned pads for up to 2 additional 0805
output capacitors.
NOTE: Capacitors must be X5R or X7R dielectric formulations. Do not use Y5V
or any similar dielectric.
Application Note EP5368QI Eval Board
May 2008 V1.0
Page 6 of 7
Enpirion Confidential
C3
C4 N/U
C10
FB1
C5 N/U
TP2
1
2
TP1
1
2
0805
0603
J1
ASP12192002
1
2
3
5
6
7
9
10
11
13
14
15
17
18
19
Vin
Vout
Vin
TP6 1
TP81
TP51
ENABLE
VS0
VS1
VS2
R1
N/U
R2
N/U
J3
1
2
3
LLM
+
C8
U2
N/U
Vin
TP71
D1
C1 N/U
C2
0805
0805 0805
0603
0805
U1
Enpirion 3x 3 Module
NC(SW)
1
PGND
2
LLM
3
Vfb
4
Vsense
5
AGND
6
VOUT
7
VOUT
8
VS3 9
VS2 10
VS1 11
VS0 12
Enable 13
Vin 14
NC(SW) 15
NC(SW) 16
C9
N/U
0805
0805
VS3
Input Protection
Figure 4: 3x3 Module Evaluation Board Schematic
Not supported
for EP5368QI
Note: LLM and VS3
are no-connect (NC)
pins for the EP5368QI.
Application Note EP5368QI Eval Board
May 2008 V1.0
Page 7 of 7
Enpirion Confidential
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.
