The TPS92390 device is a high-voltage LED driver for large screen display LED backlight applications. PWM input is used for brightness control by default. Alternatively, the brightness can also be controlled by I2C Interface.

The boost frequency, LED PWM frequency, and LED string current are configured with external resistors through the BST_FSET, PWM_FSET, and ISET pins. The INT pin is used to report faults to the system. Fault interrupt status can be cleared with the I2C interface, or is cleared on the falling edge of the EN pin.

The TPS92390 supports pure PWM dimming. The six LED current drivers provide up to 200 mA per output and can be tied together to support higher current LEDs. The maximum output current of the LED drivers is set with the ISET resistor and can be optionally scaled by the LEDx_CURRENT[11:0] register bits with I2C interface. The LED output PWM frequency is set with a PWM_FSET resistor. The number of connected LED strings is configured by the LED_SET resistor, and the device automatically selects the corresponding phase shift mode. For example, if the device is set to 4-strings mode, each LED output is phase shifted by 90 degrees with each other(= 360 / 4). Unused outputs, which must be connected to GND, will be disabled and excluded from adaptive voltage and won't generate any LED faults.

A resistor divider connected from V_OUT to the FB pin sets the maximum voltage of the boost. For best efficiency, the boost voltage is adapted automatically to the minimum necessary level needed to drive the LED strings by monitoring all the LED output voltages continuously. The switching frequency of the boost regulator can be set between 100 kHz and 2.2 MHz by the BST_FSET resistor. The boost has a start-up feature that reduces the peak current from the power-line during start-up. The TPS92390 can also control a power-line FET to reduce battery leakage when disabled and provide isolation and protection in the event of a fault.

Fault detection features of TPS92390 include:

• Open-string and shorted LED detection
  • LED fault detection prevents system overheating in case of open or short in some of the LED strings
• LED short-to-ground detection
• ISET/BST_FSET/PWM_FSET/LED_SET/MODE resistor out-of-range detection
• Boost overcurrent
• Boost overvoltage
• Device undervoltage protection (VDD UVLO)
  • Threshold sensing from VDD pin
• V_IN input overvoltage protection (V_IN OVP)
  • Threshold sensing from VSENSE_P pin
• V_IN input undervoltage protection (V_IN UVLO)
  • Threshold sensing from UVLO pin
• V_IN input overcurrent protection (V_IN OCP)
  • Threshold sensing across voltage between VSENSE_P pin and VSENSE_N pin
• Thermal shutdown in case of die overtemperature