ON Semiconductor

The CAT4026 is a high performance, large panel LED controller designed to control six constant current high voltage LED strings. Added control circuitry monitors the lowest cathode voltage and generates a feedback control signal to an external Switch Mode Power Supply (SMPS) to provide a low cost and efficient solution for large panel high voltage LED backlighting.Each LED channel current is accurately matched and controlled by sensing an external resistor in series with a low cost bipolar power transistor. This allows current and heat dissipation concerns to be mitigated from the CAT4026 device package.For added system reliability, both Open-Cathode-Anode (OCA) and Shorted-Cathode-Anode (SCA) fault detection circuitry has been included along with independent Fault flag logic outputs for diagnostic purposes.LED current dimming in all six channels can be precisely controlled by either a Pulse Width Modulation signal via the PWM input pin or by an analog dimming voltage applied at the ANLG pin. In addition the ANLG pin provides a convenient method for limiting the overall maximum power dissipation in the event of excessive LED shorting within any LED string.The device will automatically enter low current shutdown mode by taking the PWM pin low for an extended length of time.

The CAT4104 provides four matched low dropout current sinks to drive high-brightness LED strings up to 175 mA per channel. The LED channel current is set by an external resistor connected to the RSET pin. The LED pins are compatible with high voltage up to 25 V supporting applications with long strings of LEDs.The EN/PWM logic input supports the device enable and high frequency external Pulse Width Modulation (PWM) dimming control.Thermal shutdown protection is incorporated in the device to disable the LED outputs whenever the die temperature exceeds 150°C.

The CAT4109 is a 3-channel constant-current LED driver, requiring no inductor. LED channel currents up to 175 mA are programmed independently via separate external resistors. Low output voltage operation of 0.4 V at 175 mA allows for more power efficient designs across wider supply voltage range. The three LED pins are compatible with high voltage up to 25 V supporting applications with long strings of LEDs.Three independent control inputs PWM1, PWM2, PWM3, control respectivelly LED1, LED2, LED3 channels. The device also includes an output enable (OE) control pin to disable all three channels independently of the PWMx input states.Thermal shutdown protection is incorporated in the device to disable the LED outputs whenever the die temperature exceeds 150°C.

The CAT4134 is a high power, dual channel boost converter which provides two matched LED currents. Output current levels are controlled by one of two resistors RSET or RFLASH. When the FLASH input pin is low (movie mode), RSET sets the current. When FLASH is high (flash mode), the resistor RFLASH sets the LED current. Each channel drives two or three white LEDs in series and provides a regulated current to control their brightness. Input supply down to 3V is supported, making the device ideal for Li-Ion battery applications.High frequency low noise operation allows the device to be used with small external inductors and ceramic capacitors while still maintaining excellent efficiency. When not in use the device can be placed into a 'zero' quiescent mode via the shutdown pin.In addition to soft-start control and current limiting, the CAT4134 include thermal shutdown protection. A dedicated overvoltage pin (OVP) allows the user to limit the maximum LED supply voltage.