EP53A8xQI Evaluation Board User Guide
February 2012
Page 1 of 7
www.enpirion.com
Enpirion EP53A8xQI DC/DC Converter
Module Evaluation Board
Introduction
Thank you for choosing Enpirion, the source for Ultra small foot print power
converter products!
This application note describes how to test the EP53A8LQI and the EP53A8HQI
converters using the Enpirion EP53A8QI Eval Board shown in Fig. 1. In addition
to this document you will also need the device datasheet for a thorough
evaluation of the power converter module.
The EP53A8xQI converters are a complete power system on chip or PowerSoC.
• These devices are complete modules including magnetics, and require
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 a 0603
input capacitor and a 0805 output capacitor.
• Pads are available to add up to one additional input capacitor and one
additional output capacitor for evaluation of performance over a wide
range of input/output capacitor combinations.
• Pads are available to populate an external voltage divider (for feedback) if
desired. The pads are labeled R1 and R2. Pads are also available for
placing an optional feed-forward capacitor (labeled C9) across resistor R1
to modify the compensation.
• Jumpers are provided for easy programming of the following signals:
o Enable
o VS0-VS2 output voltage selection pins
• 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.
EP53A8xQI Evaluation Board User Guide
February 2012
Page 2 of 7
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Quick Start Guide
STEP 1: Set the “ENABLE” jumper to the Disable Position. Set VS0,
VS1 and VS2 pins for the desired output setting.
CAUTION: The signal pins ENA, VS0, VS1 and VS2 must be
connected to a logic “high”, jumper 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.
CAUTION: Be mindful of the polarity and the voltage magnitude. If VIN is
greater than 6V, 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 Tables 1 and 2 to determine the setting.
CAUTION: The external resistor divider is not populated
in the standard board configuration. Choosing the “EXT”
option for the EP53A8LQI 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.
CAUTION: Please note the polarity of the output terminals is opposite
from the input terminals.
STEP 5: Move the ENABLE jumper to the enabled position, and power up the
board. The EP53A8xQI should now be operational.
“0”
“1”
Output Disabled
Jumper
EP53A8xQI Evaluation Board User Guide
February 2012
Page 3 of 7
www.enpirion.com
Figure 1. Evaluation Board Layout
Output Voltage Select
The EP53A8xQI utilizes a 3 pin output voltage select scheme. The output
voltage is programmed by setting the VSx jumpers to either logic “1” or logic “0”
as described in the Quick Start section. Tables 1 and 2 show the truth table for
VOUT selection. There are seven preset output voltage levels for the EP53A8LQI,
and eight preset levels for the EP53A8HQI.
Table 1. EP53A8LQI Output Voltage Select Table
VS2 VS1 VS0 VOUT
0 0 0 1.50
0 0 1 1.45
0 1 0 1.20
0 1 1 1.15
1 0 0 1.10
1 0 1 1.05
1 1 0 0.8
1 1 1 EXT
EP53A8xQI Evaluation Board User Guide
February 2012
Page 4 of 7
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Table 2. EP53A8HQI Output Voltage Select Table
VS2 VS1 VS0 VOUT
0 0 0 3.3
0 0 1 3.0
0 1 0 2.9
0 1 1 2.6
1 0 0 2.5
1 0 1 2.2
1 1 0 2.1
1 1 1 1.8
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 low-loop-inductance 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. For more accurate
ripple measurement, please refer to Enpirion Output Ripple
Measurement Methods Application Note.
Please contact techsupport@enpirion.com for any questions regarding this
evaluation board.
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.
EP53A8xQI Evaluation Board User Guide
February 2012
Page 5 of 7
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Using the External Voltage Divider
The EP53A8xQI evaluation board is designed to provide a great deal of flexibility
in evaluating the performance of the Enpirion DC/DC module.
Pre-tinned pads are provided to place 0805 sized resistors on the board to
implement an external resistor divider for the EP53A8LQI to choose an output
voltage other than one of the pre-set voltages available on the VID. See Figur e 3
for the basic circuit.
VIN VSense
VS0
VS2
EP53A8L
10μF
0805
4.7uF
0603
VOUT
VOUT
AGND
ENABLE Ra
Rb
VFB
VS1
PGND
AVIN
PVIN
100 Ohms
Figure 3. External divider schematic for the EP53A8LQI
The output voltage is selected by the following formula:
()
Rb
Ra
OUT VV += 16.0
Ra must be chosen as 237kΩ to maintain control loop stability. Then Rb is given
as:
Ω
−
=6.0
102.142 3
2OUT
Vx
R
The external voltage divider option is chosen by setting the jumpers VS0 – VS3
to logic “high”.
EP53A8xQI Evaluation Board User Guide
February 2012
Page 6 of 7
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Dynamically Adjustable Output
The EP53A8xQI is designed to allow for dynamic switching between the
predefined voltage levels by toggling the VID pins. The inter-voltage slew r ate 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
driver to toggle between the various VOUT states.
Evaluation Board Schematic
R3
100
0402
C10 10u
FB1
742792012
TP2
1
2
TP1
1
2
Schematic 03400
PCB 03401
J1
ASP12192002
1
2
3
5
6
7
9
10
11
13
14
15
17
18
19
Vin
Vout
Vin
U1
EP53A8xQI
NC(SW)1
1
PGND
2
PGND
3
Vfb
4
Vsense
5
AGND
6
VOUT
7
VOUT
8
VS2 9
VS1 10
VS0 11
Enable 12
AVIN 13
PVIN 14
NC(SW)15 15
NC(SW)16 16
TP6 1
TP5 1
TP71
TP81
ENABLE
VS0
VS1
VS2
R1
N/U
R2
N/U
N/U
D1
S2A
+
C8
47u U2
N/U
Vin
Input Protection
C4
N/U
TP3
TP4
Place TP3 and TP4
around 100 mil apart
C1 N/U
C2 4.7u
0805 0805
0603
0603
0805
1206
X5R
C10 10u
X5R
X5R0805
C9
N/U
0805
Figure 4: EP53A8QI Evaluation Board Schematic
NOTE: Input/Output capacitors
must be X5R or X7R dielectric
formulations. Do not use Y5V or
any similar dielectric.
EP53A8xQI Evaluation Board User Guide
February 2012
Page 7 of 7
www.enpirion.com
Contact Information
Enpirion, Inc.
Perryville III
53 Frontage Road Suite 210
Hampton, NJ 08827
Tel.908.894.6000
Fax: 908-894-6090
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.
