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MAX17671FEVKIT#
Evaluation Kit
Evaluates: MAX17671 5V Step-Down
Converter and 3.3V Linear Regulator
Output Voltage Application
Benefits and Features
General Description
The MAX17671F evaluation kit (EV kit) is a fully assem-
bled and tested circuit board that demonstrates the
performance of the MAX17671F dual-output regulator
integrating a high-efficiency, high voltage, fixed output
voltage, synchronous step-down DC-DC converter, and
a high-PSRR, low-noise, fixed-output linear regulator.
The EV kit is designed for a high efficiency solution, and
generates a 5V step-down converter output voltage and
a fixed 3.3V linear regulator output voltage at load cur-
rents up to 150mA and 50mA, respectively. When the
linear regulator output is loaded, the step-down converter
output current is reduced by I
LDO
, where I
LDO
is the
load current on the linear regulator output. The EV kit
draws only 70µA supply current under no-load conditions.
The step-down converter is programmed to a switch-
ing frequency of 200kHz and delivers a peak efficiency
of 90% with the supplied components. The dual-output
device is simple to use and easily configurable with
minimal external components. The EV kit features adjust-
able input undervoltage lockout, open-drain
RESET
sig-
nal, hysteretic peak current-limit protection and external
frequency synchronization.
●
6.5V to 60V Input-Voltage Range for the Step-Down
Converter
●
5V Step-Down Converter Output Voltage, Up To
150mA Continuous Load Current
●
3.3V Linear Regulator Output Voltage, Up To 50mA
Continuous Load Current
●
Peak Efficiency of 90% for the Step-Down Converter
●
70µA No-Load Supply Current
●
200kHz Switching Frequency
●
Internal Soft-Start
●
EN/UVLO Input, Resistor-Programmable UVLO
Threshold
●
MODE/SYNC Pin to Select PWM or PFM Mode
●
Open-Drain
RESET
Output to Monitor Dual Outputs
●
External Frequency Synchronization
●
Overcurrent and Overtemperature Protection
●
Proven PCB Layout
●
Fully Assembled and Tested
Ordering Information
appears at end of data sheet.
319-100220; Rev 0; 7/18
MAX17671FEVKIT#
Evaluation Kit
Quick Start
Required Equipment
●
●
●
●
MAX17671FEVKIT#
6.5V to 60V, 200mA DC-input power supply
Two loads capable of sinking 150mA and 50mA
Two digital voltmeters (DVM)
Evaluates: MAX17671 5V Step-Down
Converter and 3.3V Linear Regulator
Output Voltage Application
6.5V to 60V and the input of the linear regulator is con-
nected to the output of the step-down converter. The EV
kit is designed for a high efficiency solution, and gener-
ates a 5V step-down converter output voltage and a fixed
3.3V linear regulator output voltage at load currents up to
150mA and 50mA, respectively. When the linear regulator
output is loaded, the step-down converter output current
is reduced by I
LDO
, where I
LDO
is the load current on the
linear regulator output. The EV kit draws only 70µA sup-
ply current under no-load conditions. The step-down con-
verter is programmed to a switching frequency of 200kHz
and delivers a peak efficiency of 90% with the supplied
components. The dual-output device is simple to use and
easily configurable with minimal external components.
The EV kit features adjustable-input undervoltage lockout,
open-drain
RESET
signal, hysteretic peak current-limit
protection and external frequency synchronization.
This EV kit includes an EN/UVLO PCB pad and JU1 to
enable the step-down converter output at a desired input
voltage. The MODE/SYNC PCB pad and JU2 are pro-
vided for selecting the intended mode of operation and
to allow an external clock to synchronize the step-down
converter. A
RESET
PCB pad is available for monitoring
the
RESET
output.
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)
Set the power supply at a voltage between 6.5V and
60V. Disable the power supply.
Connect the positive terminal of the power supply
to the VIN PCB pad and the negative terminal to
the nearest GND PCB pad. Connect the positive
terminal of the 150mA load to the VOUT PCB pad
and the negative terminal to the nearest GND PCB
pad. Connect the positive terminal of the 50mA load
to the OUTL PCB pad and the negative terminal to
the nearest GND PCB pad.
Connect the DVMs across the VOUT PCB pad and
the nearest GND PCB pad, and across the OUTL
PCB pad and the nearest GND PCB pad.
Verify that the jumper JU1 is open (see
Table 1).
Select the shunt position on the jumper JU2 accord-
ing to the intended mode of operation (see
Table 2).
Turn on the DC power supply.
Enable the loads. If linear regulator output is not
loaded, step-down converter output can be loaded
up to 150mA. Else, it can be loaded up to (150 -
I
LDO
)mA, where I
LDO
is the load current on the
linear regulator output in mA.
Verify that the DVMs display 5V and 3.3V.
Vary the input voltage from 6.5V to 60V, and vary
the load currents on step-down converter and linear
regulator outputs, and verify that the output voltages
of step-down converter and linear regulator are 5V
and 3.3V, respectively.
3)
Setting the Input EN/UVLO Level
4)
5)
6)
7)
The device offers an adjustable-input undervoltage lock-
out level. Set the voltage at which the device turns on
with a resistive voltage-divider connected from IN to GND.
Connect the center node of the divider to EN/UVLO as
shown in
Figure 1.
Choose R1 to be 3.3MΩ and then
calculate R2 as follows:
R2
=
R1
×
1.215
(V
INU
−
1.215)
8)
9)
where V
INU
is the voltage above which the device is
required to turn on. The allowed minimum value of V
INU
is 4V. See
Table 1
for proper jumper settings.
V
IN
R1
IN
Detailed Description
MAX17671F
EN/UVLO
The MAX17671F evaluation kit (EV kit) is a fully assem-
bled and tested circuit board that demonstrates the
performance of the MAX17671F dual-output regulators
integrating a high-efficiency, high voltage, fixed output
voltage, synchronous step-down DC-DC converter, and a
high-PSRR, low-noise, fixed output linear regulator. The
step-down converter operates over a wide input range of
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R2
GND
Figure 1. Setting the Input-Undervoltage Lockout
Maxim Integrated
│
2
MAX17671FEVKIT#
Evaluation Kit
MODE Selection and External Clock
Synchronization (MODE/SYNC)
Evaluates: MAX17671 5V Step-Down
Converter and 3.3V Linear Regulator
Output Voltage Application
frequency programmed by the resistor (R5) connected
to the RT pin. The minimum external clock on-time and
off-time pulse-widths should be greater than 100ns.The
jumper JU2 must be unconnected before applying the
external clock at the MODE/SYNC pin.
The EV kit provides a
RESET
PCB pad to monitor the
step-down converter output voltage and the linear regula-
tor output voltage.
RESET
goes to high impedance 2.1ms
after both step-down converter and linear regulator out-
puts rise above 95% of their nominal set value, if V
INL
is
above V
INL_UVLO
(2.18V typ) during startup. Otherwise,
RESET
only considers step-down converter output volt-
age for its high impedance state. Refer to the MAX17671
IC data sheet for more information.
The device features a MODE/SYNC pin for selecting
either forced PWM or PFM mode of operation. If the
MODE/SYNC pin is grounded, the device operates in a
constant-frequency PWM mode at all loads. If the MODE/
SYNC pin is unconnected, the device operates in PFM
mode at light loads. Refer to the MAX17671 IC data
sheet for more information on PWM and PFM modes of
operation.
Table 2
shows the EV kit jumper settings that can be used
to configure the desired mode of operation.
The internal oscillator of the device can be synchro-
nized to an external clock signal on the MODE/SYNC
pin. The external synchronization clock frequency must
be between 1.1 x f
SW
and 1.4 x f
SW
, where f
SW
is the
RESET
Output
Table 1. Step-Down Converter Enable (EN/UVLO) Description (JU1)
SHUNT POSITION
Not installed*
1-2
*Default position.
EN/UVLO PIN
Connected to the center node of
resistor-divider R1 and R2
Connected to GND
OUTPUT
Enabled, UVLO level set through
the R1 and R2 resistors
Disabled
Table 2. MODE/SYNC Description (JU2)
SHUNT POSITION
1-2
Not installed*
*Default position.
MODE/SYNC PIN
Connected to GND
Unconnected
MODE
PWM Mode of operation
PFM Mode of operation
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Maxim Integrated
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MAX17671FEVKIT#
Evaluation Kit
MAX17671F EV Kit Performance Report
(V
IN
= 24V, unless otherwise noted.)
MAX17671F, 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
toc01
Evaluates: MAX17671 5V Step-Down
Converter and 3.3V Linear Regulator
Output Voltage Application
100
90
80
70
MAX17671F, 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
100
90
80
toc02
V
IN
= 36V
EFFICIENCY (%)
EFFICIENCY (%)
60
50
40
30
20
10
0
0.00
V
IN
= 24V
V
IN
= 12V
V
IN
= 6.5V
V
IN
= 48V
V
IN
= 60V
70
60
50
40
30
20
10
0
0.001
V
IN
= 60V
V
IN
= 48V
V
IN
= 36V
V
IN
= 24V
V
IN
= 12V
V
IN
= 6.5V
0.05
0.10
0.15
LOAD CURRENT (A)
CONDITIONS: PWM MODE, f
SW
= 200kHz
0.010
0.100
LOAD CURRENT (A)
CONDITIONS: PFM MODE, f
SW
= 200kHz
MAX17671F, 5V OUTPUT
LOAD AND LINE REGULATION
5.04
toc03
MAX17671F, 5V OUTPUT
LOAD AND LINE REGULATION
5.15
V
IN
= 6.5V
V
IN
= 12V
toc04
OUTPUT VOLTAGE (V)
5.03
V
IN
= 12V
V
IN
= 36V
V
IN
= 60V
5.10
V
IN
= 24V
V
IN
= 36V
V
IN
= 48V
5.02
V
IN
= 6.5V
5.01
V
IN
= 24V
V
IN
= 48V
OUTPUT VOLTAGE (V)
5.05
V
IN
= 60V
5.00
5.00
0.00
0.05
0.10
0.15
LOAD CURRENT (A)
CONDITIONS: PWM MODE, f
SW
= 200kHz
4.95
0.00
0.05
0.10
0.15
LOAD CURRENT (A)
CONDITIONS: PFM MODE, f
SW
= 200kHz
MAX17671F, 5V OUTPUT
LOAD TRANSIENT BETWEEN 0mA AND 50mA
toc05
MAX17671F, 5V OUTPUT
LOAD TRANSIENT BETWEEN 100mA AND 150mA
toc06
V
OUT(AC
)
100mV/di
v
V
OUT(AC)
100mV/div
I
OUT
50mA/div
I
OUT
50mA/div
100µs/div
CONDITIONS: PWM MODE, f
SW
= 200kHz
100µs/div
CONDITIONS: PWM MODE, f
SW
= 200kHz
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Maxim Integrated
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4
MAX17671FEVKIT#
Evaluation Kit
Evaluates: MAX17671 5V Step-Down
Converter and 3.3V Linear Regulator
Output Voltage Application
MAX17671F EV Kit Performance Report (continued)
(V
IN
= 24V, unless otherwise noted.)
MAX17671F, 5V OUTPUT
LOAD TRANSIENT BETWEEN 1mA AND 50mA
toc07
MAX17671F, 5V OUTPUT
CLOSED LOOP BODE PLOT
40
PHASE
toc08
100
V
OUT(AC)
100mV/div
GAIN (dB)
20
50
0
GAIN
0
I
OUT
50mA/div
-20
BANDWIDTH = 12.2kHz
PHASE MARGIN = 59.7°
-40
-50
400µs/div
CONDITIONS: PFM MODE, f
SW
= 200kHz
-100
10k
100k
FREQUENCY (Hz)
CONDITIONS: PWM MODE, f
SW
= 200kHz, 150mA LOAD
1k
MAX17671F, 5V OUTPUT
STEADY STATE AT 150mA LOAD
V
OUT(AC)
MAX17671F, 5V OUTPUT
STEADY STATE AT NO LOAD
toc10
toc09
20mV/div
V
OUT(AC)
20mV/div
V
LX
10V/div
V
LX
10V/div
I
LX
I
LX
100mA/div
2µs/div
CONDITIONS: PWM MODE, f
SW
= 200kHz
100mA/div
2µs/div
CONDITIONS: PWM MODE, f
SW
= 200kHz
MAX17671F, 5V OUTPUT
STEADY STATE AT 5mA LOAD
toc11
MAX17671F, 5V OUTPUT
SOFT-START FROM EN/UVLO
toc12
V
OUT(AC)
100mV/div
V
EN/UVLO
5V/div
V
LX
10V/div
V
OUT
I
LX
2V/div
100mA/div
5V/div
I
LX
40µs/div
CONDITIONS: PFM MODE, f
SW
= 200kHz
100mA/div
V
RESET
1ms/div
CONDITIONS: PWM MODE, f
SW
= 200kHz, 33Ω RESISTIVE LOAD,
RESET
IS PULLED UP TO V
OUT
WITH A 100kΩ RESISTOR
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5
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