TI TPS61169DCKR

The TPS61169 is a boost converter with an integrated 40V-rated switch FET for driving LED strings. It integrates a 40V, 1.8A MOSFET with a minimum current limit of 1.2A, capable of driving single LEDs or LED strings for small to large panel backlighting. The default white LED current is set via an external sense resistor RSET, with the feedback voltage regulated to 204mV. During operation, the LED current can be controlled by a PWM signal applied to the CTRL pin, where the duty cycle determines the feedback reference voltage. The TPS61169 does not burst LED current, eliminating audible noise on the output capacitor. For optimal protection, the device integrates an LED open-circuit protection feature that disables the TPS61169 under an open-LED condition to prevent the output voltage from exceeding the IC's maximum absolute ratings. The TPS61169 is available in a space-saving 5-pin SC70 package.

The TPS61169 is a high-efficiency, high-output voltage boost converter in small package size. The device integrates 40-V/1.8-A switch FET and is designed for output voltage up to 39 V with a switch peak current limit of 1.2 A minimum. Its large driving capability can drive single or parallel LED strings for small to large size panel backlighting.

The TPS61169 operates in a current mode scheme with quasi-constant frequency. It is internally compensated for maximum flexibility and stability. The switching frequency is 1.2 MHz, and the minimum input voltage is 2.7 V. During the on-time, the current rises into the inductor. When the current reaches a threshold value set by the internal GM amplifier, the power switch MOSFET is turned off. The polarity of the inductor changes and forward biases the schottky diode which lets the current flow towards the output of the boost converter. The off-time is fixed for a certain VIN and VOUT, and therefore maintains the same frequency when varying these parameters.

However, for different output loads, the frequency slightly changes due to the voltage drop across the RDS(ON) of the power switch MOSFET, this has an effect on the voltage across the inductor and thus on tan (tOFF remains fixed). The fixed off-time maintains a quasi-fixed frequency that provides better stability for the system over a wider range of input and output voltages than conventional boost converters. The TPS61169 topology has also the benefits of providing very good load and line regulations, and excellent line and load transient responses.

The feedback loop regulates the FB pin to a low reference voltage (204 mV typical), reducing the power dissipation in the current sense resistor.

• 2.7V to 5.5V input voltage
• Integrated 40V, 1.8A MOSFET
• LED string drive voltage up to 38V
• 1.2A switch current lower limit
• 1.2MHz switching frequency
• 204mV reference voltage
• Internal compensation
• PWM dimming control
• LED open-circuit protection
• Undervoltage protection
• Built-in soft-start
• Thermal shutdown
• Efficiency up to 90%

• Smartphone backlight
• Tablet backlight
• PDA, handheld PC, GPS receiver
• Portable media player, portable TV
• White LED backlight for compact media players