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.
2
100
90
80
70
Efficiency (%)
60
50
40
30
20
10
0
2
4
6
8
10
12
L o a d C u r r e n t (A )
Vout (V)
3 .4 5
3 .4 4
3 .4 3
3 .4 2
3 .4 1
3 .4 0
3 .3 9
3 .3 8
3 .3 7
3 .3 6
3 .3 5
0
2
4
6
8
10
12
L o a d C u rre n t (A )
Vin=12V
Vout=3.3V
Vin=12V
Vout=3.3V
Figure 1. Efficiency vs Load
Figure 2. Load Regulation
Vin=12V
Vout=3.3V
Vout
Vin=12V
Vout=3.3V
Vout
Iout (5A/div)
Iout (5A/div)
Figure 3. Load Step Response: 0->5A
Figure 4. Load Step Response: 5->10A
Vout
Vin
SoftStart
Vout
Vin
SoftStart
Iout (5A/div)
Iout (5A/div)
Figure 5. Start-Up Response: No Load
Figure 6. Start-Up Response: 5A Load
Vout
SoftStart
SoftStart
Iout (5A/div)
Ichoke(10A/div)
Vin
Vout
Figure 7. Start-Up Response: 10A Load
Figure 8. Output Load Short Circuit
3
The SP6132EB is design for ease of a quick modification to accommodate for
applications that required both different input/output load voltage and current levels.
The change such that modification requiring only simple few on board components
direct replacement as show on the following Table 1.
Table 1: SP6132EB Suggested Components
SP6132EB Suggested Components for Different Input Voltage and Output Current Applications
QT, QB
DS
L1
C1, C2
C3, C4
R4
R5
5V Input, 2A Output
Fairchild Semi
OUTEasy Magnet
TDK
TDK
Panasonic
FDS6162N3
SD75-6R8M
C3225X5R0J476M
C3225X5R0J476M
ERJ-3EKF3322V
20V, 21A, 4.5mOhm
6.8uH, 2.54Arms,46mOhm 47uF Ceramic X5R 6.3V 47uF Ceramic X5R 6.3V 332K Ohm, 1%
Layout Size SO-8
Layout Size 7.8 x 7.0 mm Layout Size 1210
Layout Size 1210
Layout Size 0603
C1 IN and C2 OUT
C3 IN and C4 OUT
Yageo America
9C06031A0R0JLHFT
0.0 Ohm, 1%
Layout Size 0603
5V Input, 0 to 15A Output
Fairchild Semi
OUTEasy Magnet
FDS6162N3
SC5018-2R7M
20V, 21A, 4.5mOhm
2.7uH, 15.0A, 4.10mOhm
Layout Size SO-8
Layout Size 12.6 x 12.6 mm
TDK
TDK
Panasonic
C3225X5R0J476M
C3225X5R0J476M
ERJ-3EKF3322V
47uF Ceramic X5R 6.3V 47uF Ceramic X5R 6.3V 332K Ohm, 1%
Layout Size 1210
Layout Size 1210
Layout Size 0603
Yageo America
9C06031A0R0JLHFT
0.0 Ohm, 1%
Layout Size 0603
12V Input, 2A Output
Fairchild Semi
FDS7088N3
30V, 21A, 5mOhm
Layout Size SO-8
IN Easy Magnet
SD75-6R8M
6.8uH, 2.54Arms,46mOhm
Layout Size 7.8 x 7.0 mm
TDK
C3225X5R1C226M
22uF Ceramic X5R 16V
Layout Size 1210
C1 IN and C2 OUT
TDK
Panasonic
C3225X5R0J476M
ERJ-3EKF1003V
47uF Ceramic X5R 6.3V 100K Ohm, 1%
Layout Size 1210
Layout Size 0603
C3 IN and C4 OUT
TDK
MMZ1608R601A
High Freq Bead Filter
Layout Size 0603
12V Input, 0 to 15A Output
Fairchild Semi
FDS7088N3
30V, 21A, 5mOhm
Layout Size SO-8
IN Easy Magnet
SC5018-2R7M
2.7uH, 15.0A, 4.10mOhm
Layout Size 12.6 x 12.6 mm
TDK
C3225X5R1C226M
22uF Ceramic X5R 16V
Layout Size 1210
TDK
Panasonic
C3225X5R0J476M
ERJ-3EKF1003V
47uF Ceramic X5R 6.3V 100K Ohm, 1%
Layout Size 1210
Layout Size 0603
TDK
MMZ1608R601A
High Freq Bead Filter
Layout Size 0603
NOTES:
Referring to +5V Bias Supply Application Schematic,
DS
(STPS2L25U)
OUT
meaning
the application is not required to installed and vice versa. The same argument is also
applying both to
C2, C4 OUT
and
C2, C4 IN.
5
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