MAX14001PMB
Evaluates: MAX14001
General Description
The MAX14001 peripheral module provides the hardware
to evaluate the MAX14001 isolated ADC to measure two
channels of data, line voltage (up to 230V AC or ±325V
DC) and load current (up to 5A). All power and communication
is with a simple USB cable—no separate field side power
is required. The integrated DC-DC converter provides
power isolation for the system and powers all field-side
circuitry. This integrated design reduces the BOM and
board dimension for building an isolated ADC system.
Refer to the MAX14001 IC data sheet for detailed
information regarding operation of the IC.
The MAX14001PMB has a 12-pin Pmod
™
-compatible
connector for SPI communication. The peripheral module
can be used in various ways. Maxim sells a low-cost
USB2PMB2 adapter board that uses the Munich GUI
software for communication through a USB cable. This is
not included with this board, but is available from Maxim
or one of our distributors. Alternatively, any microcontroller
or FPGA with a 12-pin Pmod-compatible connector for
SPI communication can be used.
Ordering Information
appears at end of data sheet.
Features
●
Easy Evaluation of the MAX14001/MAX14002
●
3.75kV
RMS
Isolation for Both Data (SPI) and Power
(DC-DC Supply)
●
Peripheral Module Is Powered from a Single 3.3V
Supply (USB2PMB2 Is USB-Powered), No Field Side
Supply Required
●
Measure AC or DC, Voltages Up to 230V AC or
±325V DC and Current Up to 5A
●
Programmable Comparator Output
●
Works With USB2PMB2 Adapter and Munich GUI
Software
●
Fully Assembled and Tested
●
Proven PCB Layout
●
RoHS Compliant
Contents
●
MAX14001PMB, including two MAX14001s
MAX14001PMB Photo
Pmod is a trademark of Digilent Inc.
19-8795; Rev 0; 3/17
MAX14001PMB
Evaluates: MAX14001
Quick Start
Required Equipment
●
MAX14001PMB peripheral module
●
USB2PMB2 adapter board
●
Micro-USB cable
●
Windows XP®, Windows® 7, Windows 8.1, or
Windows 10 PC with a spare USB port
Note:
In the following sections, software-related items are
identified by bolding. Text in
bold
refers to items directly
from the EV system software. Text in
bold and underline
refers to items from the Windows operating system.
the serial number in the
USB2PMB2’s
list to connect the
software to communicate with that module. The software
can only communicate to one module at a time.
Sample
To start continuous monitoring, click the
Sample
Continuously
button (see
Figure 1).
For a single status,
click the
Sample Once
button. Moving the cursor over the
graph area allows the user to select channel type (voltage
or current), change scale, zoom, print, or save waveforms.
Detailed Description of Hardware
Procedure
1)
2)
If the USB2PMB1 adapter is used, download software by
following the steps below to get started:
Visit
www.maximintegrated.com/evkitsoftware
to down-
load the latest version of the Munich_GUI software,
version 2.12 or later, Munich_GUISetupV2.12.ZIP.
Save the software to a temporary folder. Unzip the
.ZIP file and double-click the .EXE file to run the
installer. A message box asking
Do you want to
allow the following program to make changes to
this computer?
can appear. If so, click
Yes.
The installer includes the drivers for the hardware and
software. Follow the instructions on the installer and
once complete, click
Finish.
The default location of
the software is in the program files directory.
Connect the MAX14001PMB Pmod connector X1 to
the connector on USB2PMB2.
Connect the USB2PMB2 to the PC with the Mini-USB
cable. Windows should automatically recognize the
device and display a message near the
System Icon
menu indicating that the hardware is ready to use.
Once the hardware is ready to use, launch the
software. The status bar in the GUI should display
Disconnected
in the bottom right-hand corner. Go to
the
Device
tab to select the MAX14001PMB.
3)
The MAX14001PMB peripheral module has two
MAX14001 devices (U11 and U51). One channel is
configured to measure the line voltage with maximum
voltage range selected by a resistor chain. The other
channel is configured to measure the voltage across a
shunt resistor to provide load current. Both AC and DC
signals can be measured. No external field side (high
voltage) power is required as the MAX14001 has an
integrated, isolated DC-DC converter. The complete
peripheral module is powered from a single 3.3V supply,
VDD, which is called the logic side (or low voltage side).
If the USB2PMB2 module is used this takes power from
the 5V supply on the USB connector to the PC. The SPI-
compatible connector uses two chip-select signals (CS1
and
CS2)
to control each chip through a single connector/
GUI interface.
4)
5)
MAX14001 Isolated ADC
6)
The MAX14001 has a free-running, 10-bit SAR ADC,
sampling at ~10ksps, that continously updates the data
register for each new conversion. If the source being
monitored is DC or low-frequency AC (such as 50Hz or
60Hz mains) this sample rate easily meets the Nyquist
criteria and, although the two ADCs are not synchronized,
the reading can be considered to be simultaneous given
the relatively high sample rate.
The device digitizes the input voltage on the field side
and transmits the data across the isolation barrier to a
data receiver on the logic side; which also has a program-
mable comparator. The host can read the ADC value from
the data receiver through the SPI interface. Additionally,
the comparator compares the digitized reading to the
programmable thresholds and outputs high if data is
above the upper threshold, and low if data is below the
lower threshold. This hardware feature is extremely use-
Detailed Description of Software
Connect to Hardware
The
Device
menu has options to search and connect to
the hardware. Use the
Scan Adapters
option to search
for the USB2PMB2 modules connected to the PC. If
modules are found, the serial numbers of the modules
are listed in the
USB2PMB
adapter drop-down list. Select
Windows and Windows XP are registered trademarks and
registered service marks of Microsoft Corporation.
www.maximintegrated.com
Maxim Integrated
│
2
MAX14001PMB
Evaluates: MAX14001
ful for setting real-time trip points, or as demonstrated, it
can be used to measure periodic signals. For example,
the frequency of the field-side input voltage can be easily
calculated using zero-crossing of the comparator output.
AC or DC Line Monitor Application
To demonstrate the features and ease-of-use of the
MAX14001, this peripheral module shows how to build an
isolated ADC and provides software demonstrating how it
can be used to measure mains power, such as a 120V,
60Hz single-phase load or 230V, 50Hz single-phase load,
with currents of a few amps.
The MAX14001 peripheral module uses two MAX14001s,
one to measure the voltage and another to measure current. The
whole board is controlled and powered by the USB2PMB2
adapter that uses the USB power from a PC. The live (L)
and neutral (N) lines are input to the board and a fuse on
the board protects circuits from large currents. Loads can
be connected to the board from the terminal connectors.
The MAX14001 has an integrated voltage reference; how-
ever, for this application, which measures AC signals, both
the positive and negative values need to be read.
Therefore, an external 1.25V shunt reference MAX6006
is used for each ADC with a DC offset of V
REF
/2 so the
negative part of the AC input is shifted above ground,
ensuring the AIN signal input is within the accepted
positive voltage range. The control registers within each
MAX14001 are set for external voltage reference source
and for pin REFIN to be a current source output, which
connects to the MAX6006.
Shunt Reference
Current Measurement
Logic Versus Field Side
The MAX14001PMB hardware has two channels, one to
measure voltage and one to measure current, as well as three
power domains with different isolated ground potentials:
●
The logic side or low-voltage side connects to the
SPI-compatible Pmod connector, and is powered
from a single 3.3V source connected to VDD,
referred to logic ground GNDL.
●
The current measurement field side, U51 provides
field-side power from VDDF1, which is nominally 3V
and can power circuitry up to 70µA. This single
supply is used to power the ADC field side circuitry in
addition to the external signal conditioning from ultra-
low bias MAX44265 op amp (U53) and precision
voltage reference MAX6006 (U52). All signals are
referenced to Field Ground 1 or GNDF1.
●
The voltage measurement field side, U11 provides
field-side power from VDDF2, which is nominally 3V
and can power circuitry up to 70µA. This single sup-
ply is used to power the ADC field side circuitry, in
addition to the precision voltage reference MAX6006
(U12). All signals are referenced to ‘Field Ground 2’
or GNDF2.
Note:
GNDF1 and GNDF2 are floating grounds only and do
not have the same potential or provide earthed protection.
The current ADC measures the voltage across a small
10mΩ sense resistor (R50) in the live wire to obtain the
live line current value. The MAX14001 accepts and ana-
log input voltage from 0 to +VREFIN. U52 (MAX6006)
is an ultra-low power shunt 1.25V voltage reference
that draws on 1µA, which is used instead of the on-chip
voltage reference to bias the input AIN at a midpoint
to allow AC or positive and negative input signals. U53
(MAX44265) is an ultra-low 4µA supply current op amp
with an ultra-low 1pA input bias current. This op amp is
configured as an inverting op amp with a gain of 10, with
its input centered around V
REF
/2 or 0.62V. The amplified
voltage across the sense resistor is ±0.500mV, allowing
head room for the maximum input range of the ADC.
Voltage Measurement
A voltage divider is used comprising R21–R26 in
conjunction with U12 voltage reference and R12–R14.
This limits the input voltage seen at pin AIN of U11 to
< 1.25V and centers it around V
REF
/2. The MAX14001
accepts positive voltage inputs at AIN from 0–1.25V with
respect to AGND, so the sense resistor and resistor divid-
ers need to be selected based on input RMS voltage and
maximum RMS. Resistor values are selected so that it is
close to but not exceeding the calculated ratio to utilize
the full ADC range. R21–R26 should be larger than 1MΩ
to ensure low current and low power consumption.
Pmod-Style Connector
The MAX14001PMB can plug directly into a Pmod-
compatible port through X1. The pin defintions are SPI-
compatible; see
Figure 2
for the X1 pinout. The ADC
readings are transmitted to the USB2PMB adapter by the
SPI interface.
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Maxim Integrated
│
3
MAX14001PMB
Evaluates: MAX14001
Figure 1. MAX4001PMB Software (Munich GUI Tab)
www.maximintegrated.com
Maxim Integrated
│
4
MAX14001PMB
B2
22K
C2
8200PF
AIN
AGND
REFIN
IC
IFET
GATE
VDDF
GNDF
GNDL
C57
1000PF
FAULT
COUT
CS
SCLK
DIN
DOUT
VDD
C58
10UF
A1
IN-
VSS
R58
R53
A2
OUT
R52
1
2
3
4
VDD
IN+ SHDN
U53
MAX44265EWT+
C1
GND
VOUT
VIN
GND
B1
39K
1
R62
F1
220K
C51
I.C.
GND
0
U52
OUT
MAX6006AEUR+
GNDF1
VDD
GNDL
R50
R59
0
C50
0.47UF
VIN
VOUT
GND
R54
0.1UF
0.01
R51
0
C53
0.1UF
C54
1000PF
7
5
3
1
9
7
5
3
1
10
8
6
4
2
8
6
4
2
GNDF1
GNDF1
GNDF1
SCLK
MISO
MOSI
CS1
VOLTAGE-MEASUREMENT
UP TO 230V AC OR +/-325V DC
VDD
VOLT-IN
VDDF2
VDD
VDD
R1
GNDF2
1000PF
VDDL
GNDL
FAULT
COUT
CS
SCLK
DIN
DOUT
VDD
GNDL
R12
R15
ISET
GNDF
AIN
AGND
REFIN
IC
IFET
GATE
VDDF
GNDF
U11
MAX14001
C15
1K
230VAC / +/-325V J1 OPEN / J2 OPEN
125VAC / +/-177V J1 CLOSED / J2 OPEN
40VAC / +/-56V J1 CLOSED / J2 CLOSED
+/-12V J1 CLOSED / J2 CLOSED / R27 = 680KOHM
120K
GNDL
4.7K
SML-P12PT
R27
MAX6006AEUR+
680K
R13
J2
0
22K
C11
C10
0.1UF
GND
C12
U12
OUT
DNI
DNI
1
GNDF2
GNDF2
GNDL
GNDL
R21
R22
R23
3
I.C.
2
0.01UF
1M
R14
6800PF
230V AC
VP+ = 325V
VP- = -325V
1M
22K
1M
R24
R25
R26
VDDF2
GNDF2
0.1UF
C13
C14
1
2
3
4
5
6
7
8
9
10
C17
1000PF
20
19
18
17
16
15
14
13
12
11
VDD
C18
10UF
FAULT
COUT2
CS2
SCLK
MOSI
MISO
1M
1M
1M
GNDF2
GNDF2
1000PF
DNI
J1
0
GNDL
Evaluates: MAX14001
GNDF2
GNDF2
C
24.9K
LED1
A
R17
GNDL
9
11
12
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VDD
U51
MAX14001
1000PF
VDDL
GNDL
C55
CURRENT-MEASUREMENT
UP TO 5A
VDD
Figure 2. MAX14001PMB Schematic
VDDF1
R56
VDDF1
GNDF
AIN
R55
120K
ISET
GNDF1
GNDL
4.7K
R57
X2
1727036
C56
R61
5.6K
2
1M
R60
1
GNDF1
VDDF1
GNDF1
GNDL
C52
0.01UF
8A
22K
3
2
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
FAULT
COUT1
CS1
SCLK
MOSI
MISO
TSW-106-08-S-D-RA
X1
VDD
11
12
10
1M
FAULT
COUT1
COUT2
CS2
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5
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