MAX17558 Dual-Phase
Evaluation Kit
Evaluates: MAX17558
General Description
The MAX17558 dual-phase EV kit provides a proven
design to evaluate the MAX17558 wide 4.5V to 60V input,
dual-phase, synchronous step-down DC-DC controller. In
2-phase operation, the two channels of the MAX17558
are operated 180° out of phase. This interleaves the
current pulses drawn by the 2 phases, and results in
reduced total RMS input current, which allows use of
lesser number of input capacitors. The EV kit provides
3.3V/20A at the outputs from a 6V to 54V input supply.
The switching frequency of the EV kit is preset to 350kHz
for optimal efficiency and component size. The EV kit features
adjustable input undervoltage-lockout and soft-start time,
selectable PWM/DCM modes, 180° out-of-phase/0° in-
phase operation, current-limit threshold, and independent
open-drain PGOOD signals.
Quick Start
Required Equipment
●
MAX17558 EV kit 6V to 54V
●
4.5V to 54V, 15A DC power supply
●
Loads capable of sinking 20A
●
Two digital voltmeters (DVM)
Procedure
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation.
Caution: Do not turn on
the power supply until all connections are completed.
1)
2)
Ensure that the DC power supply is disabled. Set the
power supply voltage to 24V.
Set the load to 20A. Disable the load in the case of an
electronic load. Leave the load unconnected in the
case of a resistor load and ensure that the resistor
power rating is high enough to dissipate the output
power.
Connect the positive terminal of the power supply to
the VIN connector and the negative terminal of the
power supply to PGND connector, which is nearest
to VIN connector.
Connect a digital voltmeter across VOUT connector
and the nearest PGND connector with the positive
terminal of the DVM connected to VOUT connector.
Verify the shunts on jumpers, as described in
Table 1,
to select default settings of the EV kit.
Turn on the DC power supply.
Verify that the digital voltmeter displays the expected
voltage (3.3V±1%).
Enable the electronic load (connect the load in the
case of resistor load).
Verify that the voltmeter displays the expected voltage
(3.3V±1%).
Features
●
6V to 54V Input Range
●
Output Rails: V
OUT
: 3.3V/20A
●
350kHz Switching Frequency
●
Independent Enable Inputs
●
Independent Adjustable Soft-Start Time
●
Configurable Tracking Operation
●
Selectable PWM/DCM Modes of Operation
●
Selectable 180° Out-of-Phase/0° In-Phase Operation
●
Selectable Current-Limit Threshold
●
Independent PGOOD Outputs
●
Overcurrent, Overvoltage, and Overtemperature
Protection
●
Proven PCB Layout
●
Fully Assembled and Tested
Ordering Information
appears at end of data sheet.
3)
4)
5)
6)
7)
8)
9)
19-7857; Rev 0; 5/16
MAX17558 Dual-Phase
Evaluation Kit
Detailed Description of Hardware
Evaluates: MAX17558
The EV kit provides a proven design to evaluate the
device. The EV kit provides 3.3V/20A at the outputs from
6V to 54V input supply. The EV kit is preset to operate at
350kHz for optimum efficiency and component size.
The EV kit provides set resistors R16, R17 and R18, R19
and jumpers JU4, JU5 to enable/disable the output at a
desired input UVLO voltage. The DCM or PWM mode of
operation can be selected using JU3. JU1 allows selection
of 180°/0° phase-shift operation between the two controllers.
JU2 allows the selection of three different current-limit
thresholds for both controllers. Refer to
Table 2
through
Table 4
for additional jumper setting details.
For normal operation, the device is enabled whenever the
input voltage is greater than 4.5V and JU4 and JU5 are
open. Set the voltage at which each controller turns on
by placing a shunt across pins 1-2 on JU4 and JU5, and
adjust the resistor-divider formed by R16, R17 for controller
1 and by R18, R19 for controller 2.
Table 2
shows the EV
kit’s jumper settings for configuring the EN_ pin.
Select R17 (R19) below 10K and calculate the R16 (R18)
based on the following equation:
R16
=
R17
×
(V
INUVLO
−
1.25)
1.25
Configuring the Output Voltage (V
OUT
)
Where V
INUVLO
is the input voltage at which the controller
is required to turn on.
The device’s output voltages (V
OUT
) can be adjusted
between 0.8V to 24V through sets of feedback resistor-
dividers (R6, R7) by the following formula:
R7
=
V
OUT1
−
1)
0.8
Mode Selection (SKIP)
R6
(
The device’s SKIP pin is used to select light-load operating
mode among the PWM/DCM modes of operation.
Table
3
shows the EV kit’s jumper settings for configuring the
desired light-load operating mode.
Phase Shift Between Controllers
JU1 can be configured to switch between 0° and 180°
phase-shift of the device’s two controllers.
Table 4
shows the jumper configurations to select the phase-shift
between the two controllers.
Please refer to the MAX17558 IC data sheet to select R6
resistor values and change compensation components, as
well as output capacitors, for new output voltage settings.
Soft-Start (SS_)
The device offers an SS_ pin used to adjust the soft-start
time to limit inrush current during startup. An internal 5µA
current source charges the capacitor C21 at the SS_ pin,
providing a linear ramping voltage for output voltage reference.
The soft-start time of the output is calculated based on the
following equation:
t
ss_OUT1
C21
×
=
0.8V
5µA
Current-Limit Threshold Selection (JU2)
The current-limit threshold of both of the device’s controllers
can be selected using the JU2.
Table 5
shows the EV kit
jumper settings for selecting the current-limit threshold.
Each controller’s peak current limit can be adjusted
independently by changing the values of R1 and R2. Note
that changing R1 and R2 values affect the stability and
current-sense signal across the current sense pins. Refer
to the “Current Sensing” section of the MAX17558 IC data
sheet for calculating the current-sense resistor value.
The default soft-start time on the EV kit is approximately
2.4ms.
Switching Frequency
Enable/Undervoltage-Lockout Level (EN_)
The device’s two controllers may be independently shut
down/enabled using the EN1 and EN2 pins. The EN_
pin can be programmed at 1.25V (typ) to detect the input
undervoltage-lockout at a desired input voltage to enable/
disable the corresponding controller with 50mV (typ)
hysteresis. Connect a resistor-divider to EN_ from V
IN
to
GND to program the input undervoltage-lockout threshold
to turn on/off the corresponding controller.
The device’s switching frequency is set to 350kHz by
resistor R14. Replace R14 with another value to set the
switching frequency between 100kHz to 2200kHz. Use
the following equation to calculate R14 when reconfiguring
the switching frequency:
R
RT
=
(f
SW
+
133)
8.8
Where F
SW
is in kHz and R14 is in KΩ.
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Maxim Integrated
│
2
MAX17558 Dual-Phase
Evaluation Kit
When reconfiguring the EV kit’s switching frequency,
it may be necessary to change the loop-compensation
network’s components to new values. Refer to the
Loop
Compensation
section of the MAX17558 IC data sheet for
computing new compensation component values.
Evaluates: MAX17558
Power-Good Outputs
The EV kit provides power-good output test points
(PGOOD1 and PGOOD2) to monitor the PGOOD1 and
PGOOD2 signals. The PGOOD signals are pulled-up to
VCCINT by R21 and R20. PGOOD1 and PGOOD2 are
high when V
OUT
is within the 90%–110% range of their
programmed output voltage. When V
OUT
is outside of the
90%–110% range of their programmed output voltage,
PGOOD1 and PGOOD are pulled low.
Table 1. Default Setting of MAX17558 EV kit
JUMPER
JU1
JU2
JU3
JU4
JU5
SHUNT POSITION
Unconnected
1-2
1-2
Unconnected
Unconnected
Select 75mV current-limit threshold
Select the PWM mode of operation
Enable controller 1
Enable controller 2
FUNCTION
Configure controller 1 and controller 2 180° out-of-phase operation
Table 2. Enable Control (JU4, JU5)
JUMPER
SHUNT POSITION
Not installed
JU4
1-2
2-3
Not installed
JU5
1-2
2-3
Unconnected
Connected to the midpoint of
input UVLO divider
Connected to GND
Unconnected
Connected to the midpoint of
input UVLO divider
Connected to GND
EN
Enabled
Enabled, UVLO level is set by the
resistor divider from VIN to GND.
Disabled
Enabled
Enabled, UVLO level is set by the
resistor divider from VIN to GND.
Disabled
MAX17558 OUTPUT
Table 3. Mode Selection (JU3)
SHUNT POSITION
1-2
2-3
SKIP PIN
Connected to VCCINT
Connected to VCCINT through a 100K resistor
LIGHT-LOAD OPERATING MODE
PWM mode
DCM mode
Table 4. Phase-Shift Selection (JU1)
SHUNT POSITION
1-2
Not installed
Unconnected
SEL_PH PIN
Connected to VCCINT
0°
180°
PHASE-SHIFT
Table 5. Peak Current-Limit Threshold Selection (JU2)
SHUT POSITION
1-2
Not installed
2-3
Unconnected
Connected to GND
ILIM Pin
Connected to VCCINT
PEAK CURRENT LIMIT THRESHOLD
75mV
50mV
30mV
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Maxim Integrated
│
3
MAX17558 Dual-Phase
Evaluation Kit
EV Kit Performance Report
Evaluates: MAX17558
100
90
80
EFFICIENCY (%)
60
50
40
30
20
10
0
0
70
EFFICIENCY vs. OUTPUT CURRENT
V
OUT
= 3.3V, PWM MODE
toc01
100
90
EFFICIENCY (%)
80
70
60
50
EFFICIENCY vs. OUTPUT CURRENT
V
OUT
= 3.3V, DCM MODE
toc02
12000
10000
I
OUT
1/I
OUT
2 (mA)
8000
6000
4000
2000
0
CURRENT SHARING
V
IN
= 24V, V
OUT
= 3.3V, PWM MODE
toc03
I
OUT1
V
IN
= 12V
V
IN
= 24V V
IN
= 36V
V
IN
= 12V
V
IN
= 24V
V
IN
= 36V
I
OUT2
F
SW
= 350kHz
5000
10000
15000
20000
F
SW
= 350kHz
0
5000
10000
15000
20000
40
F
SW
= 350kHz
0
5000
10000
15000
20000
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
STARTUP FROM INPUT SUPPLY
V
IN
= 24V, V
OUT
= 3.3V, I
OUT
= 20A
toc04
STARTUP INTO PREBIASED OUTPUT
V
IN
= 24V, V
OUT
= 3.3V, I
OUT
= 0A
1V/div
toc05
OUTPUT RIPPLE
V
IN
= 24V, V
OUT
= 3.3V, I
OUT
= 20A
1V/div
VOUT
toc06
50mV/div
V
OUT
10A/div
V
OUT
10A/div
10A/div
I
OUT
2ms/div
I
OUT
2ms/div
IOUT
2µs/div
50
40
30
20
GAIN (dB)
10
0
-10
-20
-30
-40
-50
1k
CLOSED-LOOP BODE PLOT
V
IN
= 24V, V
OUT
= 3.3V, I
OUT
= 20A
PHASE
toc7
150
120
90
30
0
PHASE MARGIN (°)
60
GAIN
CROSSOVER FREQUENCY = 41.7 kHz
PHASE MARGIN = 57
◦
-30
-60
-90
-120
10k
100k
-150
FREQUENCY (Hz)
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Maxim Integrated
│
4
MAX17558 Dual-Phase
Evaluation Kit
Component Suppliers
SUPPLIER
Wurth Elektronik
Renesas Electronics
Murata Americas
Panasonic Electronic Components
Vishay Dale
TDK Corp.
Rubycon Corp.
TT Electronics/Welwyn
www.we-online.com
am.renesas.com
www.murata.com
Evaluates: MAX17558
WEBSITE
www.panasonic.com/industrial
www.vishay.com
www.tdk.com
www.rubycon.com
www.welwyn-tt.com
Note:
Indicate that you are using the MAX17558 when contacting these component suppliers.
Component Information, PCB Layout,
and Schematic
●
MAX17558DP EV BOM
●
MAX17558DP EV PCB Layout
●
MAX17558DP EV Schematic
Ordering Information
PART
MAX17558DPEVKIT#
#Denotes RoHS compliant.
TYPE
EV kit
See the following links for component information, PCB
layout diagrams, and schematic.
www.maximintegrated.com
Maxim Integrated
│
5
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