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EVB-EN5311QI

P1-P3P4-P6P7-P8
Enpirion
®
Power Evaluation Board User Guide
EN5311 PowerSoC
Output Voltage Select
VS2
VS1
VS0
V
OUT
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
The EN5311QI 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 V
OUT
selection. There are seven preset output
voltage levels which can be chosen via the VSx jumpers.
CAUTION: The standard evaluation board configuration does not
populate the external divider. Selecting the external divider option without
populating the external divider will result in unpredictable behavior but can
result in the device going into 100% duty cycle and delivering the input rail
voltage to the output.
CAUTION: All signal pins must be connected to either a logic “1”, jumper
to the left, or to a logic “0”, jumper to the right. Leaving the jumper open
will result in an indeterminate state.
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.
Table 1. Output Voltage Select Truth Table
4
www.altera.com/enpirion
Enpirion
®
Power Evaluation Board User Guide
EN5311 PowerSoC
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.
Using The External Voltage Divider
The EN5311Q-E evaluation board is designed to provide a great deal of flexibility
in evaluating the performance of the Altera Enpirion DCDC module.
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 voltages available on the VID.
Figure 2. External divider schematic.
Figure 3 demonstrates the placement of the R1 and R2 resistors.
The output voltage is selected by the following formula:
( )
2
1
16.0
R
R
OUT
VV +=
R
1
must be chosen as 200KΩ to maintain loop gain. Then R
2
is given as:
Ω
−
=
6.0
102.1
5
2
OUT
V
x
R
The external voltage divider option is chosen by setting the jumpers VS0, VS1,
and VS2 to a logic “high”.
V
IN
V
Sense
V
in
V
S1
V
S2
V
S0
EN5311QI
10µF
4.7µF
V
OUT
V
out
GND
ENABLE
V
FB
Voltage
Select
5
www.altera.com/enpirion
Enpirion
®
Power Evaluation Board User Guide
EN5311 PowerSoC
Figure 3. Placement of external divider resistors
Dynamically Adjustable Output
The EN5311QI 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 1mV/uS.
This feature can be tested by connecting the VSx jumper center pins to logic
driver to toggle between the various V
OUT
states.
Input and Output Capacitors
The input capacitance requirement is 4.7 uF. Altera 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.
6
www.altera.com/enpirion
P1-P3P4-P6P7-P8

EVB-EN5311QI

Mfr. #:
Buy EVB-EN5311QI
Manufacturer:
Intel / Altera
Description:
Power Management IC Development Tools Eval Board EN5311QI 1A Sync. Buck Convtr
Lifecycle:
New from this manufacturer.
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