SP6136 (7A MAX.)
Evaluation Board Manual
Easy Evaluation for the
SP6136ER1 12V Input, 0 to 7A
Output Synchronous Buck
Converter
Precision 0.80V ±1% High
Accuracy Reference
Small form factor
Feature Rich: Single supply operation, Overcurrent protection with auto-restart, Power
Good Output, Enable input, Fast transient
response, Short Circuit Shutdown Protection,
Programmable soft start
TSSOP Package & SMT components for
small, low profile Power Supply
SP6136EB SCHEMATIC
1
VCC
1
VCC
1
C1
0.1uF
Ci
22uF
16V
1210
DBST
SD101AWS
8 7 6 5
13
14
15
16
17
2
4
BST
VIN
UVIN
SP6136
GND
DIEPAD
VFB
SWN
ISP
ISN
12
GH
11
SWN
9
CS
RS3
CSP
0.1uF
10K1%
6.8nF
8 7 6 5
MB
8
7
6
5
SS
1
3
R4
CSS
47nF
EN
C2
0.01uF
Si4886DY
13.5mOhm
GL
4
Inter-Technical SC7232-2R2
2.2uH, 10.4 mOhm
1
1
10.0k,1%
1
2
3
CIN & COUT CERAMIC 1210 X5R
All resistors & capacitors size
0603 unless other wise specified
NP
UVIN
1
GND
Note:
R5
R3
1
1 2 3
10
SS
AGND
1
U1
4
0.1uF
GH
PW RGD
3
PGND
EN
2
GL
COM P
1
VC C
4.7uF
10V
Si4354DY
18.5mOhm
CBST
12V
8
MT
CVCC
VIN
6
VOUT
1 2 3
7
J1
PTC36SAAN
RS1
SS
5
Co
100uF
6.3V
1210
ISP
5.11k,1% RS2
ISN
PWRGD
CP1
4
5.11k,1%
3.30V
0-7A
1
GND2
9
NP
12pF
CZ2
CF1
22pF
RZ2
CZ3
RZ3
R1
68.1k,1%
560pF
30.9K,1%
270pF
1K 1%
R2
21.5k,1%
VFB
Rev 5/01/06
SP6136 Evaluation Manual
Copyright © 2006 Sipex Corporation
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
Rev 5/01/06
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.
SP6136 Evaluation Manual
Page 2 of 9
Copyright © 2006 Sipex Corporation
Output Voltage vs Load Current
Efficiency vs Load Current
100
3.320
Output Voltage (V)
Efficiency (%)
90
80
Vin=12V
Vout=3.3V
70
60
50
40
Vin=12V
Vout=3.3V
3.315
3.310
3.305
3.300
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
0.0
Load current (A)
Figure 1. Efficiency vs Load
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Load current (A)
Figure 2. Load Regulation
Vout (100mV/div)
Vout (200mV/div)
Vin=12V
Vout=3.3V
Vin=12V
Vout=3.3V
Iout(5A/div)
Iout (5A/div)
Figure 3. Load Step Response: 3.5A->7A
Figure 4. Load Step Response: 0->7A
Vin
Vin
Vout
SoftStart
Vin=12V
Vout=3.3V
Vout
SoftStart
Vin=12V
Vout=3.3V
Iout (5A/div)
Iout(5A/div)
Figure 5. Start-Up Response: No Load
Figure 6. Start-Up Response: 3A Load
Vout
Vin
SoftStart
Vout
SoftStart
Vin=12V
Vout=3.3V
Vin=12V
Vout=3.3V
Iout(5A/div)
Ichoke(25A/div)
Figure 7. Start-Up Response: 7A Load
Rev 5/01/06
Figure 8. Output Load Short Circuit
SP6136 Evaluation Manual
Page 3 of 9
Copyright © 2006 Sipex Corporation
Vout Ripple(10mV/div)
Vout Ripple(10mV/div)
Vin=12V
Vout=3.3V
Vin=12V
Vout=3.3V
SW Node
SW Node
Figure 9. Output Noise at No Load
Figure 10. Output Noise at 7A Load
INDUCTORS - SURFACE MOUNT
Inductance
(uH)
Inductor Specification
Manufacturer/Part No.
Inter-Technical
SC7232-2R2M
2.2
Series R
Isat
Size
mOhms
(A)
LxW(mm) Ht.(mm)
10.4
13.00
7.2x6.6
Inductor Type
3.20
Manufacturer
Website
Shielded Ferrite Core
www.inter-technical.com
CAPACITORS - SURFACE MOUNT
Capacitance(
Manufacturer/Part No.
uF)
22
100
TDK
C3225X5R1C226M
TDK
C3225X5R0J107M
Capacitor Specification
ESR
Ripple Current
Size
Voltage
Capacitor
Manufacturer
ohms (max)
(A) @ 45C
LxW(mm) Ht.(mm)
(V)
Type
Website
0.005
4.00
3X2
2.00
16.0
X5R Ceramic
www.TDK.com
0.005
4.00
3X2
2.00
6.3
X5R Ceramic
www.TDK.com
MOSFETS - SURFACE MOUNT
MOSFET Specification
MOSFET
N-Ch
N-Ch
Manufacturer/Part No.
VISHAY Si4354DY
VISHAY Si4886DY
RDS(on)
ID Current
Qg
Voltage
ohms (max)
(A)
nC (Typ) nC (Max)
(V)
18.50
13.5
9.0
11.0
7.0
14.5
10.5
20.0
Foot Print
Manufacturer
30.0
SO-8
www.vishay.com
30.0
SO-8
www.vishay.com
Website
Table 1: SP6136EB Suggested Components and Vendor Lists
Rev 5/01/06
SP6136 Evaluation Manual
Page 4 of 9
Copyright © 2006 Sipex Corporation
LOOP COMPENSATION DESIGN
The open loop gain of the SP6136EB can be divided into the gain of the error amplifier
GAMP(S), PWM modulator GPWM, buck converter output stage GOUT(S), and feedback resistor
divider GFBK. In order to crossover at the selected frequency fc, the gain of the error amplifier
has to compensate for the attenuation caused by the rest of the loop at this frequency. The
goal of loop compensation is to manipulate the open loop frequency response such that its
gain crosses over 0dB at a slope of –20dB/dec. The open loop crossover frequency should be
higher than the ESR zero of the output capacitors but less than 1/5 of the switching frequency
fs to insure proper operation. Since the SP6136EB is designed with ceramic type output
capacitors, a Type III compensation circuit is required to give a phase boost of 180° in order to
counteract the effects of the output LC under damped resonance double pole frequency.
Figure 11. SP6136EB Voltage Mode Control Loop with Loop Dynamic
Rev 5/01/06
SP6136 Evaluation Manual
Page 5 of 9
Copyright © 2006 Sipex Corporation
The simple guidelines for positioning the poles and zeros and for calculating the component
values for Type III compensation are as follows:
R1 = 68.1K
R2 =
0.8 × R1
Vout − 0.8
(sets output voltage)
1
CZ 3 =
ZSF × R1 ×
RZ 2 =
((6.28 × fc )
(sets first zero)
1
LC
)
2
× L × Cout + 1 Vramp
×
(sets the cross-over frequency, fc)
6.28 × fc × CZ 3
Vin
1
CZ 2 =
ZSF × RZ 2 ×
(sets second zero)
1
LC
CP1 =
1
(sets first high-frequency pole)
6.28 × fs × RZ 2
RZ 3 =
1
(sets second high-frequency pole)
6.28 × fs × CZ 3
Where ZSF=(f compensation double zero)/(f circuit double pole)
Here ZSF is set at 0.8.
As a particular example, consider for the following SP6136EB, 7AMAX with a type III Voltage
Loop Compensation component selections:
Vin = 12V
Vout = 3.30V @ 0 to 7A load
Select L = 2.2 uH => 30% current ripple.
Select Cout = 100uF Ceramic capacitor (Resr ≈ 5mΩ)
fs = 600KHz SP6136ER1 internal Oscillator Frequency
Vramp_pp = 1.0V SP6136ER1 internal Ramp Peak to Peak Amplitude
Rev 5/01/06
SP6136 Evaluation Manual
Page 6 of 9
Copyright © 2006 Sipex Corporation
Step by step design procedures:
a.
R2 = 21.8kΩ
b.
CZ3 = 272pF
c.
Let fc =80kHz then:
d.
RZ2 = 34.4kΩ
e.
CZ2 = 538pF
f.
CP1 = 7.7pF
g.
RZ3 = 0.97kΩ
h.
CF1 = 22pF to stabilize SP6136ER1 internal Error Amplify
The above component values were used as a starting point for compensating the converter
and after laboratory testing the values shown in circuit schematic of page 1 were used for
optimum operation.
Figure 12- Gain/Phase measurement of SP6136EB shown on page 1, cross-over
frequency (fc) is 85KHz with a corresponding phase of 65 degrees
Rev 5/01/06
SP6136 Evaluation Manual
Page 7 of 9
Copyright © 2006 Sipex Corporation
PCB LAYOUT DRAWINGS
Figure 13. SP6136EB Component Placement
Figure 14. SP6136EB PCB Layout Top Side
Figure 15. SP6136EB PCB Layout Bottom Side
Rev 5/01/06
SP6136 Evaluation Manual
Page 8 of 9
Copyright © 2006 Sipex Corporation
Figure 16. SP6136EB PCB Layout Inner Layer 1 & Inner Layer 2
Table 2: SP6136EB List of Materials
Line
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Ref.
Des.
PCB
U1
MT
MB
L1
DBST
C1, CBST, CS
CSP
CIN
COUT
CVCC
C2
CSS
CP1
CZ2
CF1
CZ3
R1
R2
R3, R4
R5
RZ2
RZ3
RS1, RS2
RS3
J1
(J1)
VIN, VOUT, VCC,
GIN, GO, GND, SS,
PWRGD, UVIN
Qty.
Manuf.
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
Sipex
Sipex
Vishay Semi
Vishay Semi
Inter-Technical
Vishay Semi
TDK
TDK
TDK
TDK
TDK
TDK
TDK
TDK
TDK
TDK
TDK
Panasonic
Panasonic
Not populated
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Sullins
Sullins
9
Vector Electronic
Manuf.
Part Number
146-6610-00
SP6136ER1
Si4354DY
Si4886DY
SC7232-2R2M
SD101AWS
C1608X7R1C104K
C1608JB1H682K
C3225X5R1C226M
C3225X5R0J107M
C2012X5R1A475K
C1608X7R1E103J
C1608X7R1E473K
C1608CH1H120J
C1608CH1H561J
C1608CH1H220J
C1608CH1H271J
ERJ-3EKF6812V
ERJ-3EKF2152V
Layout
Size
1.175"x1.934"
QFN-16
SO-8
SO-8
7.2x6.6mm
1.5x4.6mm
0603
0603
1210
1210
0805
0603
0603
0603
0603
0603
0603
0603
0603
Component
SP6136EB
Synchronous Buck Controller
NFET, 30V, 18.5mOhm
NFET, 30V, 13.5mOhm
2.2uH Coil 13A 10.4mOhm
Schottky, 60V
0.1 uF Ceramic X5R 16V
6.8nF Ceramic X5R 50V
22uF Ceramic X5R 16V
100uF Ceramic X5R 6.3V
4.7uF Ceramic X5R 10V
0.01uF Ceramic X7R 25V
47nF Ceramic X7R 25V
12pF Ceramic COG 50V
560pF Ceramic COG 25V
22pF Ceramic COG 50V
270pF Ceramic COG 50V
68.1K Ohm Thick Film Res 1%
21.5K Ohm Thick Film Res 1%
Vendor
Phone Number
978-667-7800
978-667-7800
402-563-6866
402-563-6867
914-347-2474
402-563-6866
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
978-779-3111
800-344-4539
800-344-4539
ERJ-3EKF1002V
ERJ-3EKF3092V
ERJ-3EKF1001V
ERJ-3EKF5111V
ERJ-3EKF2002V
PTC36SAAN
STC02SYAN
0603
0603
0603
0603
0603
.32x.12
.2x.1
10.0K Ohm Thick Film Res 1%
30.9K Ohm Thick Film Res 1%
1K Thick Film Res 1%
5.11K Ohm Thick Film Res 1%
10K Ohm Thick Film Res 1%
36-Pin (3x12) Header
Shunt
800-344-4539
800-344-4540
800-344-4539
800-344-4540
800-344-4541
800-344-4539
800-344-4539
K24C/M
.042 Dia
Test Point Post
800-344-4539
ORDERING INFORMATION
Model
Temperature Range
Package Type
SP6136EB..…...........................− 40°C to +85°C.............……..SP6136 Evaluation Board
SP6136ER1............................. − 40°C to +85°C.....................................…….16-pin QFN
Rev 5/01/06
SP6136 Evaluation Manual
Page 9 of 9
Copyright © 2006 Sipex Corporation