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SP6132EB

Evaluation Board Manual

Signal Processing Technologies 

USING THE EVALUATION BOARD

1) Powering Up the SP6132 Circuit

Connect the SP6132 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 GND 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 GND collar touching Star GND post – avoid a GND lead on the scope

which will increase noise pickup.

3) Using the Evaluation Board with Different Output Voltages

While the SP6132 Evaluation Board has been tested and delivered with the output set

to 3.30V, by simply changing one resistor, R2, the SP6132 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 ) or 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 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 SP6132CU Evaluation Board design was optimized for 12V down

conversion to 3.30V, changes of output voltage and/or input voltage will alter

performance from the data given in the Power Supply Data section. In addition, the

SP6132CU provides short circuit protection by sensing Vout at GND however for

a better and robust current limit a comparator circuit could be used as shown on

the SP6132EB Schematic.

POWER SUPPLY DATA

The SP6132 is designed with a very accurate 1.0% reference over line, load and

temperature. Figure 1 data shows a typical SP6132CU Evaluation Board Efficiency plot,

with efficiencies to 94% and output currents to 10A. SP6132CU Load Regulation shown

in Figure 2 shows only 0.3% change in output voltage from no load to 10A load. Figures

3 and 4 illustrate a 0A to 5.0A and 5.0A to 10A Load Step. Start-up Response in Figures

5, 6 and 7 show a controlled start-up with different output load behavior when power is

applied where the input current rises smoothly as the Softstart ramp increases. In

Figure 8 the SP6132CU is configured for hiccup mode in response to an output dead

short circuit condition and will Softstart until the over-load is removed. Figure 9 and 10

show output voltage ripple less than 60mV at no load to 10A load.

While data on individual power supply boards may vary, the capability of the SP6132 of

achieving high accuracy over a range of load conditions shown here is quite impressive

and desirable for accurate power supply design.

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