Datasheet
Evaluates: MAX9924U/MAX9925
MAX9924U Evaluation Kit
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figure the generator frequency. The generator can be
configured for a 5Hz, 55Hz, 2.5kHz, or 24kHz triangle-
wave signal. When configured to the 5Hz signal input
mode, the EV kit circuit is used to demonstrate the
MAX9924U internal watchdog timer’s functionality.
The EV kit also features test points to ease evaluating
the raw sensor input signals. Test point TP1 provides
access to the SENSE+ signal after passing through
resistors R5 and R6. TP2 provides access to the
SENSE- signal after passing through resistors R7 and
R8. Test point TP3 provides access to the VCC/2 volt-
age source, while TP4 provides access to GND.
Jumper Selection
The MAX9924U EV kit features several jumpers to recon-
figure the interface circuit’s mode of operation, sensor
input type, and the triangle-wave generator frequency.
Sensor Signal Source (IN+, IN-)
The MAX9924U EV kit features jumpers to select the
MAX9924U IC IN+ and IN- pin signal source, either the
EV kit’s triangle-wave generator (U2) or a user-supplied
sensor signal. The sensor signal is applied to the EV
kit’s SENSE+ and SENSE- PCB pads. For proper oper-
ation, the typical sensor signal should have a 40mV
P-P
to 300V
P-P
and a frequency range of 5Hz to 25kHz.
Table 1 lists the various jumper options for selecting
the signal source.
Triangle-Wave Generator Frequency
Selection and Enable
The MAX9924U EV kit features jumpers JU8 and JU9 to
set the EV kit’s triangle-wave generator frequency. The
generator frequency is configurable to 5Hz, 55Hz,
2.5kHz, or 24kHz. Additionally, jumper JU6 is provided
to disable the generator active IC (U2) and JU10 is
used to disconnect the ramp generator signal from the
MAX9924U IN+ pin. See Table 1 for configuring JU10.
See Table 2 for the frequency selection options for
jumpers JU8 and JU9. Table 3 lists jumper JU6
enable/disable options for U2.
Table 1. Sensor Source Configuration (JU7, JU10)
JU7 JU10 MAX9924U IN+ PIN MAX9924U IN- PIN SENSOR SOURCE
Installed Installed Connected to triangle-wave generator Connected to VCC/2 EV kit triangle-wave generator*
Open Open
Connected to SENSE+ PCB pad
through resistors R5, R6
Connected to SENSE- PC pad
through resistors R7, R8
External differential VR sensor
Installed Open
Connected to SENSE+ PCB pad
through resistors R5, R6
Connected to VCC/2
External single-ended VR
sensor
Table 2. Triangle-Wave Generator Frequency
Configuration (JU8, JU9)
JU8 JU9 FREQUENCY
Installed Open 5Hz
Installed Installed 55Hz
Open Open 2.5kHz
Open Installed 24kHz
Table 3. Triangle-Wave Generator Enable
Configuration (JU6)
JU6 PC TRACE
SHORT
U2, PIN 8
GENERATOR
OPERATION
Installed Connected to VCC Enabled
Cut open Open Disabled, not powered
*
See Table 2 for configuring the triangle-wave generator frequency.