MAX20070

• 2.7V to 5.5V Input Range for TFT Power Section
• 4.5V to 16V Input Range for LED Driver Section
• 1MHz Boost and Inverted Buck-Boost Switching Frequency on TFT Power Section
• TFT Section Output Voltages
  • +6.5V Output at 100mA (Step-Up Switching Regulator)
  • -6.5V Output at 100mA (Inverting Buck-Boost Switching Regulator)
  • +16V Output at 3mA (Positive-Charge Pump)
  • -7V Output at 3mA (Negative-Charge Pump)
• HB LED String Output Currents Configurable for 80mA or 160mA
• Demonstrates Cycle-by-Cycle Current-Limit and Thermal-Shutdown Features on Boost LED Driver
• Demonstrates Adaptive Voltage Optimization on LED Driver Section
• Proven PCB Layout and Thermal Design
• Fully Assembled and Tested

The MAX20070 evaluation kit (EV kit) demonstrates the MAX20070 IC, which is a highly integrated power supply plus LED backlight driver for automotive TFT-LCD applications. The EV kit is a fully assembled and tested surface-mount PCB that provides a complete power-management solution for small-size automotive displays. The EV kit demonstrates one buck-boost converter, one boost converter, two gate-voltage controllers, and a boost converter that powers a dual-string LED driver.

The DC-DC converter portion of the EV kit operates from a 2.7V to 5.5V DC supply voltage. The step-up switching regulator (POS) is configured for a 6.5V or 15V output that provides 100mA. The inverting buck-boost converter (NEG) generates a negative output that tracks the positive output and provides 100mA. The gate-driver power supplies consist of regulated charge pumps that generate +16V (GVDD) and -7V (GVEE) and can deliver up to 3mA each. It is also possible to completely turn off the inverting buck-boost regulator by changing the value of the R15 resistor to 140kΩ.

The LED driver section demonstrates a step-up DC-DC preregulator followed by two channels of linear current sinks. The step-up preregulator switches at 1MHz and operates as a current-mode-controlled regulator capable of providing up to 300mA for the linear circuits. Each channel is capable of operating up to 38V and provides up to 160mA. The channels are configurable for 80mA or 160mA HB LED output current.

The LED driver portion of the EV kit operates from a DC supply voltage of 4.5V up to the HB LED string-forward voltage. The EV kit can withstand a 40V load-dump condition. The EV kit also demonstrates the IC’s features, such as adaptive voltage optimization, overvoltage protection (OVP), cycle-by-cycle current limit, thermal shutdown, and digital PWM dimming operation using a digital PWM input signal to control the brightness of the HB LEDs.

The EV kit is shipped with the MAX20070, but can also be used to evaluate the MAX20070B with IC replacement of U1.

Applications

• Automotive Central Information Displays
• Automotive Dashboards
• Automotive Head-Up Displays
• Automotive Navigation System