The TPS92519-Q1 is a dual synchronous buck LED driver with a 4.5-V to 65-V input voltage range. The device can deliver up to 2 A of continuous current per channel and power two independent strings of one to 16 series-connected LEDs. The device implements an adaptive on-time current regulation control technique to achieve fast transient response. This architecture uses a comparator and a one-shot on-timer that varies inversely with input and output voltage to maintain a near-constant frequency. With the FSET pin connected to V5D the on-time generator ensure near constant frequency of 385 kHz for channel 1 and 440 kHz for channel 2. With the FSET pin grounded the on-time generator is programmed to operate channel 1 at approximately 2 MHz and channel 2 at 2.15 MHz. The on-time between two channels is offset to ensure low EMI signature. The integrated low offset rail-to-rail error amplifier enables closed-loop regulation of LED current and ensures better than 4% accuracy over a wide input, output, and temperature range.

The LED current reference is set by forcing voltage on IADJ input and can be varied from 140 mV to 2.45 V to achieve over a 16:1 linear analog dimming range. Pulse Width Modulation (PWM) dimming of the LED current is achieved by modulating the duty cycle of external voltage signal at UDIMx input. The external UDIMx input acts as an enable and directly controls the LED current. This device optimizes the inductor current response and is capable of achieving over a 1000:1 PWM dimming ratio.

The device incorporates an enhanced programmable fault feature including the following:

• Cycle-by-cycle switch overcurrent limit
• Input undervoltage protection
• Boot undervoltage protection
• Comp overvoltage protection
• Output open circuit indication
• Output short circuit indication

In addition, Thermal Shutdown (TSD) protection is implemented to limit the junction temperature at 175°C (typical). The open-drain fault output, FLTx, indicates the status of the LEDs and is forced low whenever an output open or short fault is detected by the device.

Toggling the enable input, EN, low forces the device in low-power sleep state. In this state, both channels are disabled and analog supply, V5A, is disconnected to reduce the bias current drawn by the device.