© 2022 Crocus Technology 1
Document #: CTD452 – Contactless Current Sensor Demo Board – Rev0.1
CTD452 User Guide
Referenced Devices
CT452 – XtremeSense® TMR IC
CTD452 – Evaluation Board
Introduction
This user guide describes the operation and use
of the CTD452 demo board as an engineering
tool for evaluating the CT452 IC performance in
contactless current sensing applications.
The CT452 is a differential magnetic field sensor
IC that detects a current induced magnetic flux
and outputs a voltage proportional to the AC or
DC current flow. The CT452 integrates two
patented XtremeSense® TMR flux sense
elements configured for common field rejection,
high bandwidth, high current accuracy, and
immune to external magnetic field noise. It
achieves a total output error of less than 0.7%
FS (typ) with a total lifetime drift of 1.0% FS
(typ).
The CTD452 is a 4-layer (3 oz copper) PCB
designed to test two types of contactless current
sensing methods: with a PCB trace for <75 A
PK
current or with a busbar for 300 A
NOMINAL
current.
Both the PCB current carrying trace and the
supplied copper busbar have three (3) slits for
current steering and generating a differential
magnetic field.
Features
• Total Error: 0.7% FS (Typ.)
• Available Field Ranges:
o +6 mT
o 6 mT
o +12 mT
o 12 mT
o +24 mT
o 24 mT
• Built-in Galvanic Isolation
• Low Noise Performance
• 1 MHz Operating Bandwidth
• ~300 ns Signal Response
• Immunity to Common Mode Fields
General Description
The CTD452 demo board shown in Figure 1
features:
• 1x CT452 current sense IC
• 1x 4-layer 3oz copper PCB
• 1x 100 pF SMD capacitor (optional)
• 1x 1 µF SMD capacitor
• 1x 5 pF SMD capacitor
• Six pin male header for biasing and
measurements
• 2x Metal screw connectors
• 2 Sets of nylon screws and nuts
• 1x Custom slitted busbar
The CTD452 is enabled by applying a 5.0V bias
between the V
CC
and GND pins. The voltage
corresponding to the detected flux is available
on the Out pin. The V
REF
pin provides a voltage
that is half of V
CC
while the FLTB pin provides
an active low signal for an over-field or under-
voltage condition. The FILT pin has a capacitor
C3 to improve noise performance. Figure 2
shows the schematic and table for C3 value
options. Please review the CT452 datasheet for
more detailed electrical and performance
specifications.
© 2022 Crocus Technology 2
Document #: CTD452 – Contactless Current Sensor Demo Board – Rev0.1
FIGURE 1 CTD452 DEMO BOARD
FIGURE 2 CTD452 DEMO BOARD SCHEMATIC
PCB Current Sensing
(Steady State Current < 75A
pk
)
In this configuration, the busbar is removed so
current is measured by placing the CTD452 in-
line between the supply voltage and the load as
shown in Figure 3. For DC currents the supply
voltage must be connected to the ‘Current IN’
terminal (Red) and the load is connected to the
‘Current OUT’ (Black) terminal resulting in a
current flow through the PCB trace underneath
the CT452 IC. The top layer of the EVB has the
CT452 IC as well as the signal traces routed to
the 6-pin header. The remaining 3 layers of the
PCB are used to carry the in-line current. The
maximum current passed through the EVB is
limited by the thermal capability of the PCB
layers.
FIGURE 3 CTD452 PCB CURRENT SENSING
Busbar Current Sensing
(300 A
NOMINAL)
As shown in Figure 4, the custom slitted busbar
is placed over the CT452 for measuring
currents in the range of 70~300A. It can carry
a steady state current of 300A with a peak
current of ~900A. When installing the busbar,
make sure the slit orientation is opposite to the
bottom PCB trace’s slit orientation (this is due
to the inversion of the magnetic flux). Take care
in handling the busbar and do not over-tighten
the nylon screws as this could bend the busbar.
Do not use the PCB’s Red and Black terminals,
they must be left floating when using the
busbar. Also note the DC current flow direction
shown in Figure 4.