SLVUCI3 June 2022
The current limit resistor connected to the ILIM pin configures the current limit of the TPS1HC30-Q1 device. Based off the limit of this resistor, the allowed current that passes through the high side switch can be controlled. The TPS1HC30EVM provides three different ways of configuring the effective value of the resistance on the ILIM pin:
See the Table 4-2 section for details on how to configure each one of these jumpers.
For the digital potentiometer option, the user has the ability to control the current limit via the TPL0102-100 digital potentiometer with I2C. The SDA and SCL lines of the digital potentiometer are connected to the standardized J1-9 and J1-10 pins of the BoosterPack plug-in module header. Both pins are pulled up with pullup resistors connected to the LaunchPad development kit 3.3-V power rail. For more details on how to program the TPL0102-100 device, refer to the TPL0102 Two 256-Taps Digital Potentiometers With Non-Volatile Memory data sheet.
In the TPS1HC30EVM, both channels of the digital potentiometer are connected in series with each other, allowing for a greater resolution of configurable current limit value. The target address of the TPL0102-100 is configured to be 0x56. To configure the current limit, a simple 3-byte I2C write transaction must be performed to set the configured resistance value. The first byte must be 0x00 (corresponding to the resistance value register) and the next two bytes must be the corresponding resistance codes from the table in Appendix - TPL0102-100 Resistance Codes. These two values add up in series to make up the total resistance connected to the ILIM pin of the TPS1HC30-Q1. After the STOP condition is written through the I2C line, the configured resistance value takes effect on the TPL0102-100.
For the current sense resistance connected to the SNS pin, the "SNS Pot Enable" jumper controls the source. If this jumper is populated, the "SNS" potentiometer is used to increase and decrease the resistance connected to the SNS pin. If this jumper is not populated, the solder down pad, R13, must be used to provide the necessary resistance value. The output of the TPS1HC30-Q1's SNS pin is an analog current that is a representation of the load current going through the switch. The purpose of the sense resistor is to convert this current into a voltage so that an ADC can convert it into a value for a microcontroller to use. For the TPS1HC30EVM, the voltage across the sense resistor can either be read externally through the SNS test point or from the BoosterPack plug-in module standardized analog J1-6 pin.