Rev 5/01/06 SP6136 Evaluation Manual Copyright © 2006 Sipex Corporation
Page 2 of 9
USING THE EVALUATION BOARD
1) Powering Up the SP6136EB Circuit
Connect the SP6136ER1 Evaluation Board
with an external +12V power supply.
Connect with short leads and large
diameter wire directly to the “VIN” and
“GND” posts. Connect a Load between the
“VOUT” and “GND2” posts, again using
short leads with large diameter wire to
minimize inductance and voltage drops.
2) Measuring Output Load
Characteristics
It’s best to GND reference scope and digital
meters using the Star GND post in the
center of the board. VOUT ripple can best
be seen touching probe tip to the pad for
COUT and scope ground collar touching
Star GND post – avoid a ground lead on the
probe which will increase noise pickup.
3) Using the Evaluation Board with
Different Output Voltages
While the SP6136ER1 Evaluation Board
has been tested and delivered with the
output set to 3.30V, by simply changing one
resistor, R2, the SP6136ER1 can be set to
other output voltages. The relationship in
the following formula is based on a voltage
divider from the output to the feedback pin
VFB, which is set to an internal reference
voltage of 0.80V.
Standard 1% metal film resistors of surface
mount size 0603 are recommended.
Vout = 0.80V ( R1 / R2 + 1 ) =>
R2 = R1 / [ ( Vout / 0.80V ) – 1 ]
Where R1 = 68.1KΩ and for Vout = 0.80V
setting, simply remove R2 from the board.
Furthermore, one could select the value of
the R1 and R2 combination to meet the
exact output voltage setting by restricting
R1 resistance range such that 50KΩ ≤ R1 ≤
100KΩ for overall system loop stability.
Note that since the SP6136ER1 Evaluation
Board design was optimized for 12V down
conversion to 3.30V, changes of output
voltage and/or input voltage may alter
performance from the data given in the
Power Supply Data section.
POWER SUPPLY DATA
The SP6136ER1 is designed with an
accurate 1.5% reference over line, load and
temperature. Figure 1 data shows a typical
SP6136ER1 Evaluation Board efficiency
plot, with efficiencies to 92% and output
currents to 7A. Load Regulation in Figure 2
shows only 0.12% change in output voltage
from no load to 7A. Figures 3 and 4 show
the fast transient response. Start-up
corresponding to different load conditions is
shown in Figures 5, 6 and 7, where the
input current rises smoothly as the soft-start
ramp increases. In Figure 8 the hiccup
mode gets activated in response to an
output dead short circuit condition and will
soft-start until the over-load is removed.
Figure 9 and 10 show output voltage ripple
less than 11mV over complete load range.
While data on individual power supply
boards may vary, the capability of the
SP6136ER1 of achieving high accuracy
over a range of load conditions shown here
is quite impressive and desirable for
accurate power supply design.
