an1713

Application Note 1713
ISL8126EVAL1Z Evaluation Board User Guide
Hardware Description
Recommended Equipment
The ISL8126 integrates two voltage-mode synchronous buck
PWM controllers. It can be used either for dual independent
outputs or a 2-phase single-output regulator.
• 0V to 22V power supply with at least 20A source current
capability
The ISL8126EVAL1Z evaluation board is used for performance
demo of the 2-phase single-output application. This
application note introduces the setup procedure and
performance of the ISL8126EVAL1Z evaluation board.
• Digital multimeters (DMMs)
TABLE 1. ELECTRICAL SPECIFICATIONS
PARAMETER
VIN
VOUT
MIN
TYP
MAX
UNITS
10
12
16
V
1.18
1.2
1.22
V
Rated Current
50
A
Switching Frequency
350
kHz
16
mVP-P
VOUT Peak-to-Peak Ripple
• Two electronic loads capable of sinking current up to 30A
• 100MHz quad-trace oscilloscope.
Quick Start
1. Ensure that the circuit is correctly connected to the supply
and loads prior to applying any power.
2. Adjust the input supply to be 12V. Turn on the input power
supply.
3. Verify the output voltage is 1.2V. If PGOOD is set high, the
LED2 will be green. If PGOOD is set low, the LED2 will be
red. TP4 is the test post to monitor PGOOD.
FIGURE 1. ISL8126EVAL1Z EVALUATION BOARD
December 23, 2011
AN1713.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas Inc. 2011. All Rights Reserved.
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
Application Note 1713
Circuits Description
J1 and J2 are the input power terminals.
J3 and J4 are output lugs for load connections.
The input capacitors are used to handle the input current ripples.
Two upper and two lower Renesas LFPAK MOSFETs are used for
each phase.
320nH PULSE surface mount inductors are used for each phase.
Under the 350kHz setup, the inductor current peak-to-peak ripple
is 10A at 12V input and 1.2V output.
Six SANYO POSCAP 2R5TPF470M7L are used as output
E-capacitors.
TP8 and TP10 are remote sense posts. These pins can be used to
monitor and evaluate the system voltage regulations. If the user
wants to use these test posts for remote sense, the R12 and R14
need to be changed to higher values, such as 10Ω. Also, the
related voltage sense divider needs to be increased to a higher
resistance, such as 1k.
TP12 is a test socket to hold the scope probe to check the output
waveforms.
JP4 (not populated) is used to disable the part.
JP5 is for connection of inputs of clock signal for the part to be
synchronized with.
Refer to equations on page 25 of the ISL8126 datasheet
(FN7892) to program the UVLO falling threshold and hysteresis.
The EN/FF1 and EN/FF2 pins are connected together in
ISL8126EVAL1Z. The equations are re-stated here in
Equations 1 and 2, where RUP and RDOWN are the upper and
lower resistors of the voltage divider at EN/FF pin, VHYS is the
desired UVLO hysteresis and VFTH is the desired UVLO falling
threshold.
V HYS
R UP = --------------------2 ⋅ I HYS
(EQ. 1)
where IHYS = 30µA
R UP ⋅ V ENREF
R DOWN = -------------------------------------------- where VENREF = 0.8V
V FTH – V ENREF
(EQ. 2)
NOTE: The ISL8126 EN/FF pin is a triple function pin and the
voltages applied to the EN/FF pins are also fed to adjust the
amplitude of each channel’s individual sawtooth.
Evaluating the Other Output
Voltage
The ISL8126EVAL1Z kit output is preset to 1.2V/50A. VOUT can
also be adjusted between 0.6V to 2V by changing the value of
R11 and R8 for VOUT, as given by Equation 3.
R 11 = [ ( V OUT ⁄ V REF ) – 1 ] ⋅ R 8
where VREF = 0.6V
(EQ. 3)
JP3 is the CLKOUT pin output of ISL8126.
Programming the Input Voltage
UVLO and its Hysteresis
By programming the voltage divider at the EN/FF pin connected
to the input rail, the input UVLO and its hysteresis can be
programmed. The ISL8126EVAL1Z has R19 16.5k and R1 1.82k;
the IC will be disabled when input voltage drops below 8V and
will restart until VIN recovers to be above 9V.
OUTPUT
CAP
OUTPUT
OUTPUT
CAP
CAP
OR MOSFET
OR
MOSFET
FIGURE 3. PROPER PROBE SET-UP TO MEASURE OUTPUT RIPPLE
AND PHASE NODE RINGING
FIGURE 2. PROPER TEST SET-UP
2
AN1713.0
December 23, 2011
Application Note 1713
Load Transient Circuit Set-up
1. Install the load transient circuit as indicated in the schematic.
Refer to Figure 4 for detail.
2. R50, R51 are resistors for charging/discharging the MOSFET
gates. Their resistance determines the slew-rate of the load
step. The slew-rate in this particular setup is 3A/µs.
3. When Q10 is fully turned on, its rDS(ON) in series with R48 sets
the current step amplitude. For accurate measurement,
please use 5% tolerance sensing resistor or better. R48 is also
the current sensing resistor to monitor the load step. The
resistance of the sensing resistor sets the current scale on the
oscilloscope. The amplitude of the current step in this
particular setup is 48A.
4. Apply 5V bias voltage between TP18 and TP17 (GND). Apply
3V pulse square waveform between TP15 an TP16 (GND). The
duty cycle of the pulse waveform should be small (<5%) to
limit thermal stress on R48 and Q10.
5. Monitor overshoot and undershoot at corresponding output.
.
FIGURE 4. LOAD TRANSIENT CIRCUIT
Typical Evaluation Board Performance Curves
95
VIN = 12V, Unless Otherwise Noted.
VIN
EFFICIENCY (%)
90
VOUT
85
EN/FF
80
75
70
PH
65
60
0
10
20
30
40
50
LOAD CURRENT (A)
FIGURE 5. EFFICIENCY vs LOAD (VO = 1.2V)
3
FIGURE 6. POWER-UP UNDER 50A LOAD
AN1713.0
December 23, 2011
Application Note 1713
Typical Evaluation Board Performance Curves
1.1950
VIN = 12V, Unless Otherwise Noted. (Continued)
1.210
1.206
1.1945
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.208
1.1940
1.1935
1.204
1.202
1.200
1.198
1.196
1.194
1.192
1.1930
10
12
14
16
18
20
22
24
1.190
0
10
20
INPUT VOLTAGE (V)
FIGURE 7. LINE REGULATION
30
40
50
LOAD CURRENT (A)
FIGURE 8. LOAD REGULATION
VOUT
VOUT
FIGURE 9. OUTPUT RIPPLE AT 0A LOAD
FIGURE 10. OUTPUT RIPPLE AT 50A LOAD
VOUT
VOUT
3A/µs SLEW RATE
3A/µs SLEW RATE
7
FIGURE 11. LOAD TRANSIENT (0A TO 48A STEP)
4
FIGURE 12. LOAD TRANSIENT (48A TO 0A STEP)
AN1713.0
December 23, 2011
Schematic
TP3
PVIN
VCC
COMP
COMP2
9
10
PHASE1
ISET
5
1
2
3
4
7
R51
DNP
6
5
R50
BAT54S/SOT DNP
TP18
NC_
NC
OUTA INA
V+
GND
OUTB INB
1
2
3
4
ISL89410
R48
DNP
C49
TP16
TP12
TRAN2
TP10
VSEN_REM1+
C50
1µF
TP17 DNP
TP8
VSEN_REM1-
VCC
R11
200
R8
200
R30
4.99k
1
3
R31
4.99k
VMON1
FB1
10nF
LED1
TP4
PGOOD
DNP
R12
0
R14
0
1 COMP
PGOOD
R9
0
1nF
GREEN
RED
Q9
2N7002LT1
1
R10
0
C29
DNP
VIN
R1
1.82k
C1
1nF
C3
18nF
316
R17
274
C28
DNP
C30
1µF
JP4
R18
5.23k
R19
16.5k
C4
R4
C17
0.22µF
VOUT
TP15
C11
2
R5
2k
C23
2.2µF
U2
8
D1
3 I
FB
C27
Q10
DNP
R20
0
R21
105k
C2
330pF
PVCC
R28
2.74k
4 EN/FF1
R2
2.67k
32
VMON 31
VSEN1VSEN1- 30
VSEN1+
ISEN1B
ISEN1A
BOOT1
C16
0.22µF
R6
Q3
2k
RJK0328
COMP1
JP5
5 FSYNC
2
FB2
12
11
VMON2
13
VMON
14 ISEN2B
VSEN2+
ISHARE
VSEN1+ 29
4
Q4
RJK0328
EN/VFF1
LGATE1
R3
5.1
VOUT
6 EN/FF2
2
3
2
1
C36
JP3
7 CLKOUT
34
3
2
1
5
4
DNP
PVCC
ISEN1B 28
R13
DNP
LGATE1 22
ISL8126IRZ
ISEN1A 27
C47
100µF
Q2
RJK0305
3
2
1
C42
100µF
C10
0.1µF
1
PA1513.321
10µF
PVCC 21
4
Q1
RJK0305
5
C8
0.1µF
2
C15
UGATE1 24 UGATE1
4
3
2
1
C7
0.1µF
C48
100µF
FSYNC
PGND (PAD)
2.2µF
EN/VFF2
LGATE2
BOOT1 25
2.2µF
LGATE2 20
PHASE1 23
5
C5
0.1µF
C44
100µF
C24
0.1µF
C9
0.1µF
C26
0.1µF
L1
320nH
PHASE2
8 PGOOD
5
3
2
1
DNP
R32
C21
5
DNP
C22
C18
C6
0.1µF
Q8
RJK0328
R7
Q7
RJK0328 2k
PVIN
JP2
470µF, 7mΩ
CLKOUT/REFIN
Application Note 1713
1
JP1
C35
DNP
PGOOD
UGATE2
33
2R5TPF470M7L
R29
DNP
4
3
2
1
C45
2R5TPF470M7L
C31
2R5TPF470M7L
DNP
C46
2R5TPF470M7L
0.22µF UGATE2 18
PHASE2 19
4
5
C33
C32
2R5TPF470M7L
4
BOOT2
3
2
1
C34
2R5TPF470M7L
1.2V @50A
J3
GND(VOUT-)
R15
DNP
C14
BOOT2 17
4
Q5
RJK0305
Q6
RJK0305
1
PA1513.321
3
2
1
1 VOUT
L2
320nH
C12
5
5
5
2
15 ISEN2A
C25
2.2µF
ISEN2B
2.2µF
VIN
C20
ISEN2A
R47
2
C19
2.2µF
16 VIN
PVIN
U1
J4
VOUT
R34
274
R33
2.74k
C40
10µF
C43 C38
1000µF 10µF
TP1
GND
J2
GND
C13
0.22µF
C39
10µF
VCC
12V
C37
10µF
VSEN2-
PVIN
C41
1000µF
VCC 26
J1
VIN
AN1713.0
December 23, 2011
Application Note 1713
TABLE 2. BILL OF MATERIALS
ITEM QTY
PART REFERENCE
VALUE
DESCRIPTION
PART #
MANUFACTURER
ESSENTIAL COMPONENTS
1
2
C1, C11
2
1
C4
3
8
4
1nF
CAP Ceramic Y7R, 50V, SMD, 0603
Generic
0.01µF CAP Ceramic Y5R, 50V, SMD, 0603
Generic
C5, C6, C7, C8, C9, C10, C24, C26
0.1µF
CAP Ceramic X7R, 50V, SMD, 0603
Generic
1
C3
18nF
CAP Ceramic X7R, 50V, SMD, 0603
Generic
5
4
C12, C13, C16, C17
0.22µF CAP Ceramic X7R, 50V, SMD, 0603
Generic
6
1
C23
2.2µF
CAP Ceramic X5R, 25V, SMD, 0603
Generic
7
1
C2
330pF CAP Ceramic X5R, 25V, SMD, 0603
Generic
8
2
C30, C50
1µF
CAP Ceramic X5R, 25V, SMD, 0805
Generic
9
1
C15
10µF
CAP Ceramic X5R, 50V, SMD, 0805
Generic
10
4
C37, C38, C39, C40
10µF
CAP Ceramic X5R, 50V, SMD, 1210
Generic
11
4
C42, C44, C47, C4
100µF CAP Ceramic X5R, 6.3V, SMD, 1210
Generic
12
5
C19, C20, C21, C22, C25
2.2µF
Generic
13
6
C31, C32, C33, C34, C45, C46
14
2
C41, C43
15
2
L1, L2
16
4
Q1, Q2, Q5, Q6
17
4
Q3, Q4, Q7, Q8
18
1
R3
5.1Ω
RESISTOR, SMD, 0603, 10%
Generic
19
5
R9, R10, R12, R14, R20
0Ω
RESISTOR, SMD, 0603, 10%
Generic
20
1
R21
105kΩ RESISTOR, SMD, 0603, 1%
Generic
21
1
R19
16.5kΩ RESISTOR, SMD, 0603, 1%
Generic
22
1
R1
1.82kΩ RESISTOR, SMD, 0603, 1%
Generic
232
2
R8, R11
200Ω
RESISTOR, SMD, 0603, 1%
Generic
24
3
R5, R6, R7
2kΩ
RESISTOR, SMD, 0603, 1%
Generic
25
1
R2
2.67kΩ RESISTOR, SMD, 0603, 1%
Generic
26
2
R17, R34
27
2
R28, R33
28
1
R4
29
1
R18
30
1
R47
31
1
U1
CAP Ceramic X7R, 50V, SMD, 1210
470µF POSCAP, 6.3V, SMD, D3L
2R5TPF470M7L
Sanyo
1000µF Alum. Elec. CAP 35V
ECA-1VM102B
Panasonic
320nH Inductor
PA1513.321NLT
PULSE
TRANSISTOR, N-CHANNEL, LFPAK, 30V
RJK0305DPB
RENESAS TECHNOLOGY
TRANSISTOR, N-CHANNEL, LFPAK, 30V
RJK0328DPB
RENESAS TECHNOLOGY
274Ω
RESISTOR, SMD, 0603, 1%
Generic
2.74kΩ RESISTOR, SMD, 0603, 1%
Generic
316Ω
RESISTOR, SMD, 0603, 1%
Generic
5.23kΩ RESISTOR, SMD, 0603, 1%
Generic
2Ω
RESISTOR, SMD, 1206, 1%
IC-DUAL PHASE PWM CONTROLLER, 32P,
QFN, 5x5, ROHS
Generic
ISL8126IRZ
iNTERSIL
OPTIONAL COMPONENTS OR RESISTOR JUMPERS
40
1
LED1
41
1
Q9
42
2
R30, R31
DNP
LED, SMD, 3x2.5mm, 4P, RED/GREEN
SSL-LXA3025IGC-TR LUMEX
TRANSISTOR, SOT23, 60V
2N7002LT1G
4.99kΩ RESISTOR, SMD, 0603, 1%
HIGH SPEED POWER MOSFET DRIVER
ON SEMICONDUCTOR
Generic
42
U2
43
C49
2.2µF
CAP Ceramic X5R, 25V, SMD, 0603
Generic
44
R51
16kΩ
RESISTOR, SMD, 0603, 1%
Generic
6
ISL89410IPZ
Intersil
AN1713.0
December 23, 2011
Application Note 1713
TABLE 2. BILL OF MATERIALS (Continued)
ITEM QTY
PART REFERENCE
VALUE
DESCRIPTION
PART #
7.06kΩ RESISTOR, SMD, 0603, 1%
MANUFACTURER
45
R50
Generic
46
D1
DUAL SCHOTTKY DIODE, SOT-23
BAT54S
Generic
47
Q10
TRANSISTOR, N-CHANNEL, LFPAK, 30V
RJK0305DPB
RENESAS TECHNOLOGY
48
R48
15mΩ RESISTOR, SMD, 2512, 1W
Generic
EVALUATION BOARD HARDWARE
46
1
J1
BINDING POST, RED
111-0702-001
JOHNSON COMPONENTS
47
1
J2
BINDING POST, BLACK
111-0703-001
JOHNSON COMPONENTS
48
1
J3, J4
CABLE TERMINAL, 6 -14AWG, LUG&SCREW
KPA8CTP
BERG/FCI
48
1
TP1, TP3, TP4, TP8, TP10, TP15,
TP16, TP17, TP18
TEST POINT
5002
Keystone
7
AN1713.0
December 23, 2011
Application Note 1713
FIGURE 13. ISL8126EVAL1Z EVALUATION BOARD TOP LAYER
FIGURE 14. ISL8126EVAL1Z EVALUATION BOARD 2 ND LAYER
8
AN1713.0
December 23, 2011
Application Note 1713
FIGURE 15. ISL8126EVAL1Z EVALUATION BOARD 3 RD LAYER
FIGURE 16. ISL8126EVAL1Z EVALUATION BOARD BOTTOM LAYER
Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is
cautioned to verify that the Application Note or Technical Brief is current before proceeding.
For information regarding Intersil Corporation and its products, see www.intersil.com
9
AN1713.0
December 23, 2011
Similar pages