User guide
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2022-04-26
RIC74424EVAL1 user guide
Open loop dual output gate driver with R9 FETs
Functional description
2
Functional description
2.1
Bias power
For proper operation, an external bias power supply is required for VS. The drive voltage of RIC74424 is set by
the voltage on VS. It is recommended to keep VS within the recommended operating range for RIC74424, which
is 5 V to 20 V. Bias voltage for VS can either be applied thru the banana jacks or the test points. The banana
jack and test points have independent traces to the VS bypass capacitors C17 and C18, which allow for Kelvin
measurements of VS for improved measurement accuracy. Connection details are summarized in Table 3.
Table 3
VS connections
VS polarity
Banana jack
Test point
Positive (+)
X23
X15
Return (-)
X24
X20
2.2
Logic inputs
RIC74424EVAL1 has independent PWM inputs for IN A and IN B. BNC connectors are available for both inputs to
allow for direct connection with waveform generators. Alternatively, test points are also available. Both inputs
have a low pass RC filter between both connectors and RIC74424, which intended to eliminate any potential
undesired high frequency noise. Depending on actual performance this filter can be adjusted or removed.
Additional test points, which are connected to the IN A and IN B pin after the low pass RC filter, are provided to
allow for precise measurement of the input voltage on the RIC74424 IN A and IN B pins. These test points are a
100 mil connector to allow for direct use with high accuracy active differential oscilloscope probes. Connection
details are summarized in Table 4.
Table 4
Input connector details
Channel
FET
BNC input
connector
Test point input
connector
Low pass
RC filter
Test point measurement
Positive (+) Negative (-)
Positive (+) Negative (-)
A
SMD-0.5/e (Q1)
X9
X6
X19
R5, C7
X4 pin 1
X4 pin 2
B
SupIR-SMD (Q2)
X14
X10
X19
R6, C10
X13 pin 1
X13 pin 2
2.3
Output
RIC74424EVAL1 is configured to drive two independent FET, each with their own gate drive and power stage.
2.3.1
Gate drive
The default configuration for RIC74424EVAL1 has a single gate drive resistor for both turn on and turn off. The
gate drive strength can be modified to be asymmetrical, where turn on and off strength are different, by
populating the second gate drive resistor. A diode is pre-populated in a way where this second resistor adds a
resistor in parallel during turn off transition, reducing the total resistance. Test points for the gate to source
measurement of both FET are also provided. These test points are a 100 mil connector to allow for direct use
with high accuracy active differential oscilloscope probes. Details are summarized in Table 5.
