The TPS92515 is an internal N-channel MOSFET (monolithic NFET) hysteric control, buck regulator. Hysteretic operation allows a high control bandwidth and is ideal for shunt FET and LED matrix applications (series LED switched network). The high-side differential current sense with low adjustable threshold voltage via a 10:1 divider, provides an excellent method for regulating output current while maintaining high system efficiency. The device uses a controlled OFF-time (COFT) architecture to allow the converter to operate in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) with no external control loop compensation, and provides an inherent cycle-by-cycle current limit.
The adjustable current sense threshold provides the capability for analog dimming the LED current over the full range and the PWM dimming input allows for high-frequency PWM dimming control requiring no external components. Configuration options allow for easy implementation of external shunt FET dimming. See also the OFF-Timer, Shunt FET Dimming or Shunted Output Condition section.
The device does not internally limit the maximum attainable average LED current. It does have a thermal limit based on the maximum junction temperature. The maximum junction temperature is a function of the system operating points (efficiency, ambient temperature, thermal management), component choices, and switching frequency. This functionality allows the device to provide constant currents up to 1 A in a wide variety of applications and up to 2 A in a smaller sub-set of applications. This simple regulator contains all the features necessary to implement a high-efficiency, versatile, high-performance LED driver.