Datasheet

MAX9926U Evaluation Kit
Evaluates: MAX9926U
_______________________________________________________________________________________ 3
information on the modes of operation. Lowpass sensor
input filtering for channel 1 SENSE1Q inputs is provided
by resistors-capacitor network R1–R4, C1 and channel
2 SENSE2Q inputs are provided by R14–R17, C7. PCB
pads provide access to the MAX9926U square-wave
open-drain output signals at COUT1 and COUT2 and
the direction signals. These outputs are pulled up to the
V_PULL voltage and are configurable by jumper JU10.
Additionally, PCB pads FILTER1 and FILTER2 are pro-
vided for interfacing with user-supplied microcontroller
PWM signals when evaluating Mode B of the MAX9926U,
which enables the threshold voltage to be set externally.
For FILTER1, resistor-capacitor network R23, C10 and
for FILTER2, R28, C11 provide a lowpass filter for the
PWM input signals, respectively. Refer to the Adaptive
Peak Threshold section in the MAX9926U IC data sheet
for additional information.
When fed a 5Hz signal, the EV kit circuit can be used to
demonstrate the MAX9926U’s internal watchdog timer’s
functionality.
The EV kit also features test points to ease evaluating
the raw sensor input signals. Tests points TP1 and TP2
provide access to the SENSE1+/SENSE1- input signals
after passing through resistors R1–R4. TP5 and TP6
provide access to the SENSE2+/SENSE2- input signals
after passing through resistors R14–R17. TP3 and TP4
provide access to the BIAS1 and BIAS2 reference,
respectively, while TP7 and TP8 provide access to GND.
Jumper Selection
The MAX9926U EV kit features several jumpers to recon-
figure the sensor input type, pullup voltage, and the
interface circuit’s mode of operation.
Sensor Signal Sources
(SENSE1+/SENSE1-, SENSE2+/SENSE2-)
The sensor signals are applied to the EV kit’s channel 1
SENSE1+/SENSE1- and channel 2 SENSE2+/SENSE2-
PCB pads. For proper operation, the typical differential
sensor signal should have 50mV
P-P
to 300V
P-P
and
a 5Hz to 25kHz frequency range. When evaluating
single-ended sensors, resistors R1–R4 and R14–R17
require replacement for operation at higher voltages and
power. Table 2 lists SENSE1+/SENSE1- various jumper
options for selecting the signal source and Table 3 lists
SENSE2+/SENSE2- jumper options.
Table 2. Channel 1 SENSE1+/SENSE1- Source (JU1 Configuration)
Table 3. Channel 2 SENSE2+/SENSE2- Source (JU4 Configuration)
SHUNT
POSITION
IN1+ PIN IN1- PIN SENSE1+/SENSE1- SOURCE
Not installed
Connected to SENSE1+ PCB pad
through resistors R1 and R2
Connected to SENSE1- PCB pad
through resistors R3 and R4
External differential VR sensor
Installed
Connected to SENSE1+ PCB pad
through resistors R1 and R2
Connects SENSE1- PCB pad to
GND pad
External single-ended VR sensor
SHUNT
POSITION
IN2+ PIN IN2- PIN SENSE2+/SENSE2- SOURCE
Not installed
Connected to SENSE2+ PCB pad
through resistors R14 and R15
Connected to SENSE2- PCB pad
through resistors R16, R17
External differential VR sensor
Installed
Connected to SENSE2+ PCB pad
through resistors R14 and R15
Connects SENSE2- PCB pad to
GND pad
External single-ended VR sensor