The integrated current sense circuit of the device provide a sense current (I_SNS) proportional to the load current (I_OUTx) of each channel through the SNS pin to an external sense resister (R_SNS) to create a voltage. The current sense of each channel is multiplexed internally and is outputted on the SNS pin by the ADC scheduler. The voltage created by the I_SNS and R_SNS is then sampled by the internal 10-bit ADC where the result of the ADC conversion is stored in ADC_RESULT_CHx_I for each channel. The ISNS_RDY_CHx bit is set to 1 if a new ADC conversion result exists since the register was last read.

To ensure an accurate sensing measurement by the internal ADC, the sensing resistor should be connected to the IC GND.

The device offers two current sense ratios (K_SNS1) and (K_SNS2) for each channel which can be set through the OL_ON_EN_CHx bit in the CHx_CONFIG registers. The higher K_SNS1 ratio (OL_ON_EN_CHx = 0 mode) allows for the channel to accurately measure high output current levels where the lower K_SNS2 ratio (OL_ON_EN_CHx = 1 mode) enables the channel to accurately measure low output current levels. The K_SNS1 utilizes the full mosfet where K_SNS2 utilizes a small mosfet with ON resistance, R_{ON_OL}, to provide the lower current sense ratio. To use the K_SNS2 ratio, the output current level must be below I_{ENTRY_OL_ON} before the OL_ON_EN_CHx bit is set to 1. If the current is not below I_{ENTRY_OL_ON}, the K_SNS2 operation will not be entered and the K_SNS1 operation will still be active. If the channel is operating with K_SNS2 and the output current increases above I_{EXIT_OL_ON}, the device will automatically transition out of K_SNS2 to K_SNS1 where the OL_ON_EN_CHx bit will be reset to 0 and the full mosfet is active. If the current falls below I_{ENTRY_OL_ON} again then the OL_ON_EN_CHx bit needs to be set back to 1 to transition to K_SNS2 operation again. The system can manually exit K_SNS2 operation by writing OL_ON_EN_CHx = 0. When measuring the output current through the integrated ADC in K_SNS2 operation, the system should continue to monitor the OL_ON_EN_CHx = 1 bit to ensure the device is still in K_SNS2 operation when the output current measurement is read.

The device also offers a voltage scaling option to amplify the current sense voltage at the ADC input. At low output current levels this helps to allow the current sense voltage to be at higher levels of the integrated ADC. The voltage scaling is set through the ISNS_SCALE_CHx bit. Table 8-11 below provides the different settings for the ISNS_SCALE_CHx. ISNS_SCALE_CHx = 1 operation is recommended only in OL_ON_EN_CHx = 1 mode.

It is recommended to only use OL_ON_EN_CHx = 1 mode and/or ISNS_SCALE_CHx = 1 with I2T disabled (I2T_EN = 0). If OL_ON_EN_CHx = 1 and/or ISNS_SCALE_CHx = 1 is used with I2T enabled (I2T_EN = 1) this could cause the channel to turn off at unintended lower I2T thresholds.

The ISNS_SCALE_EFF_CHx bit in the ADC_RESULT_CHx_I register, will provide an indication if the channel is operating with 1x or 8x voltage scaling so the system knows which voltage scaling factor to apply when converting the current sense measurement.

The ADC conversion equation for current sense for different OL_ON_EN_CHx settings are below:

with OL_ON_EN_CHx = 0,

with OL_ON_EN_CHx = 1,

The current sense function is enabled for each channel by default. The current sense function can be enabled or disabled globally through the ADC_ISNS_DIS bit in the ADC_CONFIG register. When the global ADC_ISNS_DIS bit is 0 the device will enable or disable the current sense function on each channel according to the ISNS_DIS_CHx bit in the respective CHx_CONFIG registers.

If I2T protection is used, the current sense function has to be enabled before the I2T protection can be used. The current sense function is only available when the channel is enabled and in the steady state operation. The current sense function is not available in the inrush period.