Evm Components; Input Current; Input Filter Options; First Order And Sallen Key Filter Options - Texas Instruments INA901EVM-CVAL User Manual

EVM Components

5 EVM Components
This section summarizes the INA901EVM-CVAL components.
5.1

Input Current

J1 is the primary input terminal of the INA901EVM-CVAL. This terminal allows the EVM to be placed in
series with a bus voltage and load current. R1 is able to be fitted with a size 2512 resistor in this use case.
Alternatively, a differential voltage is able to be applied directly across the terminals of J1 to evaluate the
EVM.
5.2

Input Filter Options

Resistors R2 and R3, along with capacitor C3, form an optional filter on the inputs of the device. By
default, R2 and R3 are populated with 0-Ω resistors, and C3 is not populated. If this filter is populated, use
resistance of less than 10 Ω to minimize the introduction of additional errors.
C1 and C2 serve as additional options for common mode filtering on each input if desired. C1 and C2 are
not populated by default.
5.3

First Order and Sallen Key Filter Options

C5 is populated by default with a 15-pF capacitor which, along with the internal 96-kΩ resistor at the PRE
OUT pin of U1, forms a first-order filter between the PRE OUT and BUF IN stages of U1.
By default, C6 is not populated, and R4 is populated with a 0-Ω resistor. These values may be changed
along with C5 to form a second order Sallen-Key filter. See the Device Functional Modes section of the
INA901-SP Radiation Hardened, –15-V to 65-V Common Mode Unidirectional Current-Shunt Monitor Data
Sheet for additional information on how to configure this.
5.4

Comparator

The "A" channel of comparator U2 is configured by default as an overcurrent detector. Resistors R6 and
R7 are configured by default so that the comparator reference is ½ of V+. As V+ also sets the full scale
output range of the INA901, this sets the overcurrent point of the comparator to ½ of the full scale output
range of the INA901, or when V
by adjusting the values of R6 and R7.
5.5

Unused Comparator Channel and Best Practices

The "B" channel of comparator U2 is unused by default. Resistors R8, R9, and R11 are configured in
accordance with the Unused Comparator Connections section of the
LM339, LM393, TL331 Family Comparators Including the New B-versions Application
5.6

Comparator Disconnect

If the INA901 needs to be evaluated without other devices present, R5 can be depopulated to disconnect
the INA901 from the comparator.
10
INA901EVM-CVAL Evaluation Module User's Guide
> 125 mV for a supply voltage of 5 V. This set point can be changed
SENSE
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SBOU216A – October 2018 – Revised June 2020
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