an1772

Application Note 1772
Author: Jun Liu
ISL78200EVAL1Z Evaluation Board Setup Procedure
The ISL78200EVAL1Z board is used to demonstrate the
synchronous/asynchronous buck or boost buck operation of
the ISL78200.
The ISL78200EVAL1Z board input voltage range is 3V to 40V.
The output voltage is set to 5V and can be changed by voltage
feedback resistors. Note that to make the output voltage higher,
the output capacitors’ voltage rating needs to be checked.
The board output current is 2A typical. The board is set at to a
default overcurrent threshold of 3.6A . The OC threshold can be
programmed by the resistor at the ILIMIT pin.
The ISL78200EVAL1Z board has setting options, which can be
configured to synchronous buck, asynchronous buck,
boost-buck topologies, forced PWM mode or PFM mode.
The board is set to a default frequency of 500kHz. The
frequency can be programmed by the resistor at the FS pin.
The board can be synchronized to the external clock. Multiple
ISL78200EVAL1Z boards can be synchronized simply by
connecting their SYNC pins together.
Recommended Equipment
• 0V to 40V power supply with at least 5A source current
capability
• Load capable of sinking current up to 3A
• Multimeters
• Oscilloscope
Input and Output Connectors
The board has 2 main circuits sections - buck and boost, as
shown in Figure 1.
1. For synchronous/asynchronous buck, the inputs are
J1(VIN+) and J2(GND). The outputs are J3(VOUT+) and
J4(GND).
2. For boost buck operation, the inputs of the boost are
J5(VIN_BOOST+) and J6(GND) and the boost output positive
terminal is J31(VOUT_BOOST+). By shorting J26 and J27,
the boost outputs are connected to the inputs of the buck.
The outputs of the buck are still J3(VOUT+) and J4(GND).
BOOST
BUCK
FIGURE 1. ISL78200EVAL1Z BOARD IMAGE
August 6, 2012
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Copyright Intersil Americas Inc. 2012. All Rights Reserved.
1-888-INTERSIL or 1-888-468-3774 | 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 1772
Board Setup and Startup
Sequence
Synchronous Buck
1. Ensure J25 is shorted for the voltage feedback connection.
2. Ensure J30 is shorted for non-boost mode.
3. The MODE and GND pins of J7 are shorted for forced PWM
mode (no PFM). If PFM mode is desired, short MODE pin to
VCC pin of J7 or leave MODE pin floating.
4. J11 is shorted to have AUXVCC connected to VOUT, and J13,
J10, J12 should be OPEN. If AUXVCC switch-over function is
not desired, open J11 and short J13.
5. Leave all the other jumper connectors open.
6. Connect the power source to the inputs J1(VIN+) and J2(GND).
Connect the load terminals to the buck outputs J3(VOUT+)
and J4(GND). Make sure the setup is correct prior to applying
any power or load to the board.
7. Adjust the power source to 12V and turn it on.
8. Verify the output voltage is 5V and use the oscilloscope to
monitor the phase node waveforms (J28).
Asynchronous Buck
1. Ensure J25 is shorted for the voltage feedback connection.
2. Ensure J30 is shorted for non-boost mode.
3. Ensure the MODE and GND pins of J7 are shorted with jumper
for forced PWM mode (no PFM). If PFM mode is desired, short
MODE pin to VCC pin of J7 or leave MODE pin floating.
4. Ensure J11 is shorted for AUXVCC connected to VOUT setup,
and J13, J10, J12 should be OPEN. If AUXVCC switch-over
function is not desired, open J11 and short J13.
5. Remove R19. Change R20 (on bottom of the board) to 0Ω to
keep Q6 securely off.
6. Leave all the other jumpers connectors open.
drops below 7V; and the boost will stop switching when boost
input recovers to be above 10V.
6. Open J13 and J11, and short J12 to set up the boost output
overvoltage protection. R24 and R25 are used to set up the
boost output OVP threshold. With 1MΩ at R24 and 42.2kΩ at
R25, the boost PWM will be turned off when the boost output
voltage reaches 25V and recovers switching when it drops
below 22V.
7. Leave all the other jumpers connectors open.
8. Short J14 to disable the IC prior to applying the power source
to boost inputs.
9. Connect the power source to the boost inputs J5(VIN_BOOST+)
and J6(GND). Connect the load terminals to the buck outputs
J3(VOUT+) and J4(GND). Make sure the setup is correct prior
to applying any power or load to the board.
10. Adjust the power source to 12V and turn it on.
11. Open J14 to enable the IC.
12. Verify the buck output voltage is 5V. Use the oscilloscope to
monitor the buck phase node waveforms (J28) and the boost
phase node waveforms (J17).
13. Adjust the input voltage down to 5V to start up the boost. Note
the boost input voltage cannot be too low and it is limited by
the current ratings of the boost switch and boost inductor. The
boost input current will increase upon the decrease of boost
input voltage. The input current should be estimated before
turning the input voltage extremely low under heavy load
(refer to the boost operation description section in the
datasheet for more details).
14. The shutdown sequence must be: short J14 to shut down the
IC first, then turn off the power source at the boost input. To
turn off the power source (boost input) first with the circuits
operating at boost mode could cause damage to the boost
MOSFET and IC resulting from the current stress at boost
switches and inductors. In designs using boost mode, the
same shutdown sequence must be followed.
7. Connect the power source to the inputs J1(VIN+) and J2(GND).
Connect the load terminals to the buck outputs J3(VOUT+)
and J4(GND). Make sure the setup is correct prior to applying
any power or load to the board.
8. Adjust the power source to 12V and turn it on.
9. Verify the output voltage is 5V and use oscilloscope to monitor
the phase node waveforms (J28).
Boost Buck
1. Remove R19 and leave it open. Change R20 (on bottom of the
board) to 0Ω to keep Q6 securely off.
2. Install 0Ω resistor at R9 to set up LGATE to drive the boost
switch Q5.
3. Short jumpers J26 and J27 to connect the boost outputs to
buck inputs.
4. Ensure J25 is shorted with jumper for the voltage feedback
connection.
5. Open J30 and short J34 to set the IC in boost mode. R17 and
R18 are used to set up the boost on/off threshold divided
from boost input. With R17 = 130kΩ and R18 = 1MΩ, the
boost will start to operate when VIN_BOOST+(J5) voltage
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Application Note 1772
TABLE 1. CONNECTORS/TEST POINTS DESCRIPTIONS
TEST POINT
DESCRIPTION
J1
VIN+, positive terminal of buck inputs.
J2
GND, ground terminal of buck inputs.
J3
VOUT+, positive terminal of buck outputs.
J4
GND, ground terminal of buck outputs.
J5
VIN_BOOST+, positive terminal of boost inputs.
J6
GND, ground terminal of boost inputs.
J7
Mode setup connector. Connecting the MODE pin to GND will set the IC in forced PWM mode; leaving the MODE pin open or
connected to VCC sets the IC to have PFM available under light load condition. The default PFM current threshold for the IC is 0.7A.
R16 is a placeholder for a resistor to program the PFM current threshold.
J8
Test points used to monitor boost input. For monitoring purposes only. Do not short it with jumper.
J9
Test points used to monitor buck input. For monitoring purposes only. Do not short it with jumper.
J10
N/A. Leave open.
J11
With J11 shorted, VOUT+ is connected to AUXVCC for the switchover function. The IC switches over from main LDO to auxiliary LDO
after VOUT is built-up.
J12
In boost buck mode, with J12 shorted, the AUXVCC pin monitors boost output voltage through R24 and R25 providing overvoltage
protection.
J13
Use this connector to apply any voltage to AUXVCC as the AUXLDO input. Short it to ground when AUXVCC is not used.
J14
Use this connector to control IC ON/OFF.
J15
Test points used to monitor the FB pin. For monitoring purposes only. Do not short it with jumper.
J16
Use to set up switching frequency. With the FS pin connected to VCC or GND, or left open, the default frequency of the IC is 500kHz.
R8 is a placeholder for a resistor to program frequency.
J17
Test points used to monitor the boost phase node. For monitoring purposes only. Do not short it with jumper.
J18
Use it to configure synchronization.
Option 1: to apply external clock for the IC to be synchronized with.
Option 2: to synchronize multiple ISL78200, simply connect those SYNC pins together.
J22
Test points used to monitor the boost output. For monitoring purposes only. Do not short it with jumper.
J23
Test points used to monitor the COMP pin. For monitoring purposes only. Do not short it with jumper.
J24
N/A. Leave open.
J25
Must short it with jumper to provide output feedback connection.
J26, J27
In boost buck configuration, short these connectors to connect boost outputs to buck inputs.
J28
Test points used to monitor the buck PHASE node waveforms. For monitoring purposes only. Do not short it with jumper.
J29
Use it to set up the overcurrent limit threshold. With the ILIMIT pin connected to VCC or GND or left open, the default OC threshold
of the IC is 3.6A. R15 is a placeholder for a resistor to program the OC threshold.
J30, J34
Connectors to set up the boost operation.
Option 1: to short J30, set the IC in non-boost mode (either synchronous or asynchronous buck mode).
Option 2: to open J30 and short J34, set the IC in boost mode. A voltage higher than 0.2V on the EXT_BOOST pin before VCC POR
ON latches the IC in boost buck mode at startup.
J31
VOUT_BOOST+, positive terminal of boost output.
J32
Test points used to monitor the LGATE. For monitoring purposes only. Do not short it with jumper.
J33
For asynchronous buck configuration; shorting it with jumper before IC startup will disable the low-side driver after IC startup.
J35
Shorting it with jumper will cause the IC’s boost to always run.
J36
Test points used to monitor the buck output voltage. For monitoring purposes only. Do not short it with jumper.
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Application Note 1772
TABLE 2. BILL OF MATERIALS
REF DES
PART NUMBER
QTY
DESCRIPTION
C3
VARIOUS
1
CAP, SMD, 0603, 1.0µF, 16V, 10%, X7R, ROHS
VARIOUS
C19,C57
EEE-FK1K220P
2
CAP, SMD, 8X10.2, 22µF, 80V, 20%, ALUM.ELEC., ROHS
PANASONIC
C1
VARIOUS
1
CAP, SMD, 0805, 4.7µF, 10V, 10%, X7R, ROHS
VARIOUS
C2,C18, C22
VARIOUS
3
CAP, SMD, 1206, 2.2µF, 50V, 10%, X7R, ROHS
VARIOUS
C8
VARIOUS
1
CAP, SMD, 0603, 100pF, 50V, 5%, C0G, ROHS
VARIOUS
C20
VARIOUS
1
CAP, SMD, 0603, 0.01µF, 16V, 10%, X7R, ROHS
VARIOUS
C16, C23
VARIOUS
2
CAP, SMD, 0603, 0.1µF, 50V, 10%, X7R, ROHS
VARIOUS
C4
VARIOUS
1
CAP, SMD, 0603, 0.022µF, 16V, 10%, X7R, ROHS
VARIOUS
C7
VARIOUS
1
CAP, SMD, 0603, 470pF, 50V, 10%, X7R, ROHS
VARIOUS
C9, C11, C26, C27, C28
DNP
0
CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS
N/A
C5
VARIOUS
1
CAP, SMD, 1206, 10µF, 16V, 10%, X5R, ROHS
VARIOUS
C10
DNP
0
CAP, SMD, 1206, DNP-PLACE HOLDER, ROHS
N/A
C6
DNP
0
CAP, SMD, 1210, DNP-PLACE HOLDER, ROHS
N/A
C58
16SVPD82M
1
CAP-OSCON, SMD, 6.9x8.3, 82µF, 16V, 20%, 40mΩ, ROHS
SANYO
L1
DR125-100-R
1
COIL-PWR INDUCTOR, SMD, 12.5mm, 10µH, 20%, 5.35A, ROHS
COOPER/COILTRONICS
L2
DR125-6R8-R
1
COIL-PWR INDUCTOR, SMD, 12.5mm, 6.8µH, 20%, 6.64A, ROHS
COOPER/COILTRONICS
D1, D3
PDS360
2
DIODE-SCHOTTKY RECTIFIER, SMD, POWERDI5, 60V, 3A, ROHS
DIODES INC.
U1
ISL78200AVEZ
1
IC-2.5A SYNC BUCK/BOOST BUCK CONTROLLER, HTSSOP, ROHS
INTERSIL
Q5, Q6
SQS462EN
2
TRANSISTOR-MOS, N-CHANNEL, 8P, PWRPAK, 60V, 8A, ROHS
VISHAY
R6, R19
VARIOUS
2
RES, SMD, 0603, 0Ω,1/10W, ROHS
VARIOUS
R18, R24
VARIOUS
2
RES, SMD, 0603, 1M, 1/10W, 1%, ROHS
VARIOUS
R17
VARIOUS
1
RES, SMD, 0603, 130k, 1/10W, 1%, ROHS
VARIOUS
R3
VARIOUS
1
RES, SMD, 0603, 232k, 1/10W, 1%, ROHS
VARIOUS
R7
VARIOUS
1
RES, SMD, 0603, 33.2k, 1/10W, 1%, ROHS
VARIOUS
R25
VARIOUS
1
RES,SMD,0603, 42.2k, 1/10W, 1%, ROHS
VARIOUS
R4
VARIOUS
1
RES, SMD, 0603, 44.2k, 1/10W, 1%, ROHS
VARIOUS
R5, R20, R23
VARIOUS
3
RES, SMD, 0603, 5.11k, 1/10W, 1%, ROHS
VARIOUS
R2
VARIOUS
1
RES, SMD, 0603, 51.1k, 1/10W, 1%, ROHS
VARIOUS
R8, R9, R15, R16
DNP
0
RES, SMD, 0603, DNP-PLACE HOLDER, ROHS
N/A
R1, R26
DNP
0
RES, SMD, 0805, DNP-PLACE HOLDER, ROHS
N/A
D2
DNP
0
DO NOT POPULATE OR PURCHASE
N/A
4
MANUFACTURER
AN1772.0
August 6, 2012
ISL78200EVAL1 Schematic
TP12
D3
C18
J22
VIN_BOOST+
J34
J6
TP13
E
E
J15
2
R6
DNP
E
R8
R18
1M
R17
130K
SQS462-EN
R2
VOUT+
J36
C16
0.1UF
C58
82UF
C6
OPEN
J3
GND
J4
TP3
TP2
PGOOD
220K
R15
1
R16
J29
2
3
1
J7
2
VCC
R5
E
5
4
Q6
5.11K
DNP
E
J16
6
VCC
E
1
7
3
E
FB
VCC
3
2
R20
J23
TP8
E
0
J28
10PF
R7
ISL78200AVEZ
E
E
12
11
EPAD
E
J14
FB
+5V/2A
10.0UH
C5
COMP
SS
8
10UF
ILIMIT
FS
R19
LGATE
1
R1
EN
9
10
VCC
DNP
13
AUXVCC
8
J33
C27
14
7
TP1
DR125-100-R
L1
PHASE
PGOOD
MODE
ILIMIT
COMP
FB
OPEN
MODE
VCC
E
ILIM
E
15
6
21
C4
R25
J12
PGOOD
SGND
E
C9
1M
PHASE
16
EN
0.01UF
J13
R24
42.2K
VOUT_BOOST+
C20
VOUT+
FS
SS
AUXVCC
17
5
18
33.2K
J11
PHASE
0.022UF
J10
EXT_BOOST
EXT_BOOST
VIN
C8
4.7UF
VCC
VIN
4
C7
5.11K
470PF
R4
R3
44.2K
232K
J24
VOUT_BOOST+
J25
VOUT+
DNP
3
E
ISL78200
EVAL BOARD
SCHEMATIC
TIM KLEMANN
8/16/2011
JUN LIU
E
ISL78200EVAL1Z
FIGURE 1. ISL78200EVAL1Z BOARD SCHEMATIC
REV.C1.0
Application Note 1772
C1
E
GND
3
SYNC
EXT_BOOST
MODE
19
0
J30
SYNC
J32
BOOT
C3
2
LGATE
1UF
LGATE
20
BOOT
PGND
VIN+
GND
J18
1
VCC
EXT_BOOST
DNP
U1
TP11
E
1N4148W-7-F
BOOT
100PF
C22
C23
0.1UF
GND
E
2.2UF
J9
C57
E
D2
C28
C11
5
TP10
VIN+
22UF
EEEFK1K220P
J2
0.1UF
VCC
VIN+
J1
J35
E
OPEN
E
D1
SQS462-EN
VIN+
J26
2.2UF
5
C10
4
OPEN
6
DNP
7
3
J31
J27
J17
2
R26
8
C26
R23
GND
1
5.11K
DNP
VOUT_BOOST+
PDS360-13
Q5
R9
LGATE
J8
C2
C19
22UF
EEEFK1K220P
2.2UF
6.8UH
DR125-6R8-R
OPEN
J5
PDS360-13
L2
VIN_BOOST+
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Application Note 1772
Board Layouts
FIGURE 2. TOP COMPONENTS SILKSCREEN
FIGURE 3. TOP LAYER
FIGURE 4. 2 nd LAYER
FIGURE 5. 3 rd LAYER
FIGURE 6. BOTTOM LAYER
FIGURE 7. BOTTOM COMPONENTS SILKSCREEN
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Application Note 1772
Board Layouts (Continued)
FIGURE 8. TOP COMPONENT ASSEMBLY
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
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