USER’S MANUAL
ISL8130EV1Z
Evaluation Board
AN1760
Rev 2.00
Aug 7, 2012
Introduction
ISL8130EV1Z is a standard boost converter, which features
the universal PWM controller, ISL8130. The evaluation board
delivers 32V output at 1.25A. All the necessary components
are within the 1.425” x 1.15” PCB area.
The ISL8130 is a universal PWMcontroller. It is designed to
drive N-Channel MOSFETs in a synchronous rectified buck
topology for up to 25A instant MOSFET current and can be
configured for boost, buck/boost and sepic converters as well.
The ISL8130 integrates control, output adjustment, monitoring
and protection functions into a single package. The ISL8130
provides simple, voltage mode control with fast transient
response.
Evaluation Board Specifications
TABLE 1. EVALUATION BOARD ELECTRICAL SPECIFICATIONS
SPEC
VIN
IOC
VOUT
IOUT
IOUT
V
IN
= 6V
V
IN
= 12V
V
IN
= 6V, I
OUT
= 1.25A
V
IN
= 12V, I
OUT
= 2.5A
DESCRIPTION
Board Input Range
Input Current
MIN
6
8
30.5
1.25
2.5
90
93.5
32
33.5
TYP
12
MAX
16
UNIT
V
A
V
A
A
%
%
ISL8130 Key Features
• Operates From:
- - 4.5V to 5.5V Input for 5V Input
- - 5.5V to 16V Input
• Resistor-Selectable Switching Frequency from 100kHz to
1.4MHz
• Voltage Margining and External Reference Tracking Modes
• Kelvin Current Sensing
- Upper MOSFET r
DS(ON)
for Current Sensing for Buck and
Buck/Boost Converter
- Precision Resistor for Boost and Sepic Converter
• Extensive Protection Functions:
- Overvoltage, Overcurrent, Undervoltage
• Power-Good Indicator
FIGURE 1. ISL8130EV1Z TOP VIEW
TABLE 2. RECOMMENDED COMPONENT SELECTION FOR QUICK EVALUATION
V
OUT
(V)
32
24
12
NOTES:
1. Please select the output capacitor with a voltage rating higher than the output.
2. Please contact
Intersil Sales
for assistance.
R22
(k)
174
130
63.4
V
IN
(MIN)
(V)
6
9
4.5
I
OUT
(A)
1.25
2
3
F
SW
(KHz)/R
T
(K)
330kHz/43.2k
500kHz/28.7k
500kHz/28.7k
MOSFET
BSC100N06LS G
BSC059N04 LS
BSC057N03 LS
FORWARD DIODE
SS5P6
SS3P4L
SS5P3
INDUCTOR (L, ISAT)
10µH, 10A
10µH, 7A
2.2µH, 15A
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Aug 7, 2012
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ISL8130EV1Z
ISL8130EV1Z
FIGURE 2. ISL8130EV1Z TEST SET-UP
Recommended Equipment
The following equipment is recommended for evaluation:
• 0V to 20V power supply with 15A source current capability
• Electronic load capable of sinking 2A @ 40V
• Digital Multi meters (DMMs)
• 100MHz Quad-Trace Oscilloscope
Probe Set-up
Quick Test Setup
1. Ensure that the Evaluation board is correctly connected to the
power supply and the electronic load prior to applying any
power. Please refer to Figure 2 for proper set-up.
2. Leave JP3 in the open position
3. Turn on the power supply; V
IN
< 16V
4. Adjust input voltage V
IN
within the specified range and
observe output voltage. The output voltage variation should
be within 5%.
5. Adjust load current within 1.25A. The output voltage variation
should be within 5%.
6. Use oscilloscope to observe output ripple voltage and phase
node ringing. For accurate measurement, please refer to
Figure 3 for proper probe set-up.
7. Optimization. Please refer to Table 2 on page 1 for
optimization recommendation.
8. For 5V input applications, please tie the VCC5V to VIN and do
not allow V
IN
to go above 5.5V.
NOTE: Test points: VIN+, VIN-, VO+ and VO- are for voltage measurement
only. Do not allow high current through these test points.
OUTPUT CAP
OUTPUT CAP
OUTPUT CAP
OR MOSFET
OR MOSFET
FIGURE 3. OSCILLOSCOPE PROBE SET-UP
VOUT Setting
The output voltage is set by the resistor divider, R
13
and R
22
.
R
13
+
R
22
V
OUT
= --------------------------
0.6V
R
13
(EQ. 1)
Resistor R
21
is a resistor jumper for loop gain measurement. It is
recommended to set R
21
= 50 for loop gain measurement.
Component Selection
Component Voltage Stress
The controller, ISL8130 and input capacitors are connected from
the VIN rail to GND. MOSFET, diode and the output capacitors are
connected from the VOUT rail to GND. Please select component
with sufficient voltage rating.
Inductor Selection
It is recommended to select inductor so that the ripple current
ratio is between 30% to 50%. For low-core-loss magnetic
material, higher ripple ratio would ease the compensation design
AN1760 Rev 2.00
Aug 7, 2012
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ISL8130EV1Z
and help to reduce the size of the inductor. Please refer to
Equation 2 for recommended indcutor value:
V
OUT
-
L
BST
= ------------------------------------------------
D
1
–
D
i
R
I
Omax
F
SW
2
For example:
V
OUT
= 32V, I
OUT
= 1.25A, VINmin = 6V
(EQ. 2)
D
max
= 81.25%
I
ORMS
= 2.6A
For applications with F
SW
< 1MHz, it is still rule of thumb that the
aluminum electrolytic capacitors take the ripple current. Please
select electrolytic capacitors with ripple current greater than the
maximum I
ORMS
, as calculated by Equation 7.
The other important factor is stability. The right-half-plane zero,
f
RHP
of a boost converter imposes a big challenge for stability. It
is recommended to set cross over frequency below the f
RHP
and
above the boost converter natural resonant frequency, f
N
. It is
recommended to use sufficient output capacitors so that the f
N
is much lower than f
RHP.
Equation 8 is provided for total output
capacitance estimation.
I
Omax
2
-
C
out
-----------------
L
BST
400
V
INmin
(EQ. 8)
Where D is the duty cycle,
i
R
is the inductor ripple ratio.
It is recommended to select an inductor with a saturation current
higher than the maximum overcurrent threshold.
Current Sensing
:
For accurate overcurrent detection, it is recommended to set the
voltage across the current sensing resistor, RCS, higher than
50mV. Taking variation into consideration, when precision
current sensing resistor is used, RSEN = 665. .
The OC threshold should be higher than the peak inductor current
at maximum load current. The maximum peak inductor usually
occurs at VINmin and can be calculated using Equation 3.
V
INmin
I
Omax
V
OUT
1
V
INmin
- -
-
-
I
LPK
= ---------------------------------- + --
-----------------------------
1
– -----------------
2 L
BST
F
SW
V
INmin
V
OUT
(EQ. 3)
where L
BST
is the boost inductor.
For right-half-plane zero calculation, f
RHP
:
V
in
-
f
RHP
= ------------------------------------
2
I
L
L
BST
(EQ. 9)
Refer to Equation 4 for R
CS
calculation.
R
SEN
I
OCSET
min
-
R
CS
---------------------------------------------------
I
LPK
(EQ. 4)
Where: I
OCSET
is the OCSET pin sinking current for overcurrent
detection. The I
OCSET(min)
= 80A.
In “Inductor Selection” on page 2, it is recommended that the
inductor saturation current be higher than the maximum
overcurrent threshold. The maximum overcurrent threshold can
be calculated by Equation 5.
R
SEN
I
OCSET
max
I
OCmax
= -----------------------------------------------------
R
CS
(EQ. 5)
For boost converter natural resonant frequency, f
N
:
1
–
D
-
f
N
= -------------------------------------------------
2
C
OUT
L
BST
(EQ. 10)
Output Disconnect
The boost converter cannot protect from an output short circuit
event. It relies on the input power supply overcurrent protection
or output disconnect circuit for output short circuit events.
Figure 4 is a simple output disconnect circuit, which can be used
as a reference. The circuit is inserted between the cathode of the
diode and the boost output.
M1
Where I
OCSET(max)
= 120A.
Input Capacitors
The input RMS current of a boost is much smaller than the
output RMS in general. Please refer to Equation 6 for input RMS
current calculation:
V
IN
V
IN
-
-
I
INRMS
= -----------------------------
1
– ------------
12
L
BST
F
SW
V
OUT
(EQ. 6)
1
R8
31.6K
2
The bulk capacitor used is used to stabilize system stability and
can be considered as the output capacitor of the input power
supply.
Output Capacitors
It is recommended to use a combination of aluminum capacitors
with high capacitance and low ESR ceramic capacitors at the
output for optimum ripple and load transient performance.
The low ESL and ESR ceramic capacitors should be placed close
to the MOSFET and diode.
When selecting the output capacitors, there are two important
requirements: the ripple current and the stability.
The output RMS current worst case occurs at VIN_min and
maximum load. See Equation 7 for output ripple current
calculation:
D
max
I
ORMS
=
I
OUT
-----------------------
-
1
–
D
max
(EQ. 7)
PGOOD
D2
11V
M2
NFET
FIGURE 4. OUTPUT DISCONNECT CIRCUIT
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Aug 7, 2012
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ISL8130EV1Z
Typical Performance Curves
95
93
VOUT REGULATION(V)
91
EFFICIENCY (%)
89
87
85
83
81
79
77
0
0.5
1.5
LOAD CURRENT(A)
1.0
2.0
2.5
VIN = 6V
VIN = 12V
32.4
32.3
32.2
32.1
32.0
31.9
31.8
31.7
31.6
0
0.5
1.0
1.5
2.0
2.5
VIN = 12V
VIN = 6V
LOAD CURRENT(A)
FIGURE 5. EFFICIENCY vs LOAD CURRENT
FIGURE 6. VOUT LOAD REGULATION
VO(AC) AT 200mV/DIV
TIME AT1µs/DIV
VO(AC) AT 200mV/DIV
TIME AT 1µs/DIV
FIGURE 7. OUTPUT RIPPLE (V
IN
= 6V, LOAD = 1.25A, 20MHz BW)
FIGURE 8. OUTPUT RIPPLE (V
IN
= 12V, LOAD = 2.5A, 20MHz BW)
VO(AC) AT 200mV/DIV
VO AT 10V/DIV
VEN/SS AT 2V/DIV
ISTEP AT 500mA/DIV
PGOOD AT 5V/DIV
TIME AT 50ms/DIV
TIME AT 1msec/DIV
FIGURE 9. SOFT-START (C
SS
- 0.47µF, C
DEL
= 0.1µF)
FIGURE 10. LOAD TRANSIENT (V
IN
= 12V, LOADSTEP FROM 0.375A
TO 1.0A)
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Aug 7, 2012
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ISL8130EV1Z
Typical Performance Curves
(Continued)
VO AT 20V/DIV
VO AT 20V/DIV
IL AT 5A/DIV
VEN/SS AT 2V/DIV
FIGURE 11. OVERCURRENT PROTECTION AT OVERLOAD WITH OUTPUT DISCONNECT (VBST IS THE OUTPUT BEFORE THE OUTPUT DISCONNECT
FET. VO IS THE OUTPUT AFTER THE DISCONNECT FET)
AN1760 Rev 2.00
Aug 7, 2012
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