February 2008 V1.0
Enpirion EN5311QI DCDC Converter
Module Evaluation Board
Introduction
Congratulations! You are evaluating a new class of DCDC converter product, a complete
power system on silicon:
• The EN5311QI is a complete module including magnetics and requiring 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 0805 4.7uF input capacitor
and a 0805 10uF 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 divider if desired.
• Easy jumpers are provided for the following signals:
o Enable
o VS0-VS2 output voltage select
• Numerous test points are provided as well as clip leads for input and output
connections
• The board comes with input decoupling and reverse polarity protection to protect
the device from common setup mishaps.
Quick Start Guide
Figure 1 shows a top view of the evaluation board.
Ou tput Disabled
Jumper
STEP 1: Set the “ENA” jumper to the Disable Position.
CAUTION: the signal pins, ENA, VS0, VS1, and VS2 must
be connected to a “high” or a “low”. If left floating the state
is indeterminate.
STEP 2: Set the output voltage select pins for the desired output voltage setting. Refer to
the section on output voltage select to determine the s
etting.
CAUTION: the external divider is not populated.
“0”
“1”
Choosing this option will force the device to 100%
duty cycle.
Page 1 of 8
Enpirion Confidential
February 2008 V1.0
STEP 3: Connect Power Supply to the input power connectors, VIN (+) and GND (-) as
CAUTION: be mindful of the polarity. Even though the evaluation board comes
STEP 4: Connect the load to the output connectors VOUT (+) and GND (-), as indicated
STEP 5: Power up the board and move the ENA jumper to the enabled position. The
indicated in Figure 1.
with reverse polarity protection diodes, it is rarely a good idea to reverse the input
polarity.
in Figure 1.
EN5311QI is now powered up.
Output Voltage
Select
Output
Enable
Figure 1. Evaluati n Board Layout.
Decouplin (to g Cap
decouple supply cables)
Reverse polarity
protection diodes CIN COUT
GND (-)
VOUT (+)
0805 4. uF
VIN (+)
GND (-)
0805 10uF7
o
Page 2 of 8
Enpirion Confidential
February 2008 V1.0
Output Voltage Select
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 User Selectable
he EN5311QI utilizes a 3 pin output voltage select scheme. The output voltage is bed
able 1 shows the truth table for VOUT selection. There are seven preset output voltage
CAUTION: the standard evaluation board configuration does not populate the
e
AUTION: All signal pins must be connected to either a lo gic “1”, jumper to lt
T
programmed by setting the VSx jumpers to either a logic “1” or a logic “0” as descri
in the Quick Start section
T
levels which can be chosen via the VSx jumpers.
external divider. Selecting the external divider option without populating the
external divider will result in unpredictable behavior but can result in the devic
going into 100% duty cycle and delivering the input rail voltage to the output.
C
the left, or to a logic “0”, jump er to the right. Leaving the jumper open will resu
in an indeterminate state.
Test Recommendations
Recommendations
Table 1. Output Voltage Select Truth Table
Page 3 of 8
Enpirion Confidential
February 2008 V1.0
To guarantee measurement accuracy, the following precautions should be observed:
t and output voltage measurements at the board using the test
cables that can produce false readings.
3. easure switching signals to avoid
1. Make all inpu
points provided. This will eliminate voltage drop across the line and load
2. Measure input and output current with series ammeters or accurate shunt
resistors. This is especially important when measuring efficiency.
Use a balanced impedance probe tip to m
noise coupling into the probe ground lead.
Using The External Voltage Divider
a great deal of flexibility in
e.
oltages available on the VID.
The EN5311Q-E evaluation board is designed to provide
evaluating the performance of the Enpirion DCDC modul
Pre-tinned pads are provided to place 0402 sized 1% resistors on the board to implement
an external resistor divider to choose an output voltage other than one of the seven pre-set
v
VIN VSense
Vin
VS1
VS2
VS0
EN5311QI
10µF
4.7µF
VOUT
Vout
GND
ENABLE
VFB
Voltage
Select
Figure 2. External divider schematic.
Figure 3 demonstrates the placement of the R1 and R2 resistors.
ula:
The output voltage is selected by the following form
()
2
16.0 R
OUT V
1R
+=
1 must be chosen as 200KΩ to m aintain loop gain. Then R2 is given as:
V
R
Ω
−
=6.0
102.1
2Vx
R
5
OUT
The external voltage divider option is chosen by setting the jumpers VS0, VS1, and VS2
to a logic “high”.
Page 4 of 8
Enpirion Confidential
February 2008 V1.0
CIN
0805 4.7uF
COUT
0805 10uF
CIN
0805 4.7uF
COUT
0805 10uF
Figure 3. Placement of external divider resistors
Dynamically Ad
itching between the predefined
voltage slew rate is optimized to
revent excess undershoot or overshoot as the output voltage levels transition. The slew
he various VOUT states.
justable Output
The EN5311QI is designed to allow for dynamic sw
voltage levels by toggling the VID pins. The inter-
p
rate is 1mV/uS.
This feature can be tested by connecting the VSx jumper center pins to logic driver to
toggle between t
Page 5 of 8
Enpirion Confidential
February 2008 V1.0
Input and Output Capacitors
The input capacitance requirement is 4.7 uF. Enpirion recommends that a low ESR
MLCC capacitor be used. The EN5311Q-E is populated with a 4.7uF 0805 capacitor.
There are pre-tinned pads that allows for additional 0805 capacitors to experiment with
input filter performance.
The output capacitance requirement is a minimum of 10uF. The control loop is designed
to be stable with up to 60uF of total output capacitance. The evaluation board comes
populated with a single 10uF 0805 capacitor.
The board has pre-tinned pads for up to 2 additional output capacitors with either 0805 or
1206 footprint.
Capacitance above the 10uF minimum can be added if the transient performance is not
sufficient using the 10uF. Enpirion recommends a low ESR MLCC type capacitor be
used.
NOTE: Capacitors must be X5R or X7R dielectric formulations.
Page 6 of 8
Enpirion Confidential
February 2008 V1.0
Page 7 of 8
Enpirion Confidential
February 2008 V1.0
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.
Page 8 of 8
Enpirion Confidential
