The two LED drivers are current regulated, temperature compensated, and adjustable with an 8-bit DAC. When the LED driver is enabled, the CSA voltage is regulated, and the current through the CSA resistor also flows through the LED and the DINA pin. A current sense resistor connects to the CSA pin. The LED driver is enabled with the LEDEN pin and LEDPIN_EN bit. Both the pin and bit must be high for the LED driver to operate. The LEDSEL bit switches which driver the LEDEN signal connects to. The GPIO pin can be configured to enable either LED driver.

The LED driver is temperature compensated to account for reduced LED intensity with increasing temperature. Four temperature compensation settings are available to support a variety of IR and blue LEDs. Temperature compensation is implemented by varying the CSA regulated voltage with temperature, thus the temperature compensation also depends on the CSA resistor. Each temperature compensation setting has a different DAC output at room temperature. To achieve a specific temperature compensation and current, the PDAC, TEMPCO, and CSA resistor must all be adjusted according to the Section 8.2.2.2 procedure.

The two LED drivers are interchangeable and support both IR and blue LEDs. The only difference between the two LED drivers is a code CSA_BIN available to improve the LED A driver current accuracy for IR LEDs. CSA_BIN in register 0x00 categorizes CSA voltage for each unit as close to the minimum, below average, above average, or close to the maximum (see Section 7.6). Use CSA_BIN to adjust the DAC and compensate for the variation on the LED A driver's current. After adjusting the DAC, the effective variation is reduced by a factor of 4 for the TEMPCOA = 11, PDAC_A = 00 setting. IR LEDs typically require the TEMPCOA = 11 temperature compensation setting. Therefore, use the LED driver A for powering IR LEDs. If better accuracy is required, calibrate the LED driver current by connecting the CSA or CSB pin to the microcontroller ADC port, measuring the CSA or CSB voltage, and adjusting PDAC_A or PDAC_B until the required current is achieved.

Ensure that the LED current remains below 550 mA, the pulse width remains below 1 ms, and the duty cycle remains below 1%. There is no protection to prevent operation outside these conditions. Ensure the PDAC and TEMPCO registers are programmed before enabling the LED driver.