ZHCSQK6 May 2022 TPS92643-Q1
PRODUCTION DATA
The TPS92643-Q1 is a wide input, synchronous buck LED driver. The device can deliver up to 3 A of continuous current and power a single string of one to 10 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. 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 the IADJ pin and is programmed by a voltage divider to achieve over a 15:1 linear analog dimming range. The high impedance IADJ input simplifies LED current binning and thermal protection.
The TPS92643-Q1 device incorporates an internal ramp generator to control LED current through pulse width modulation (PWM) dimming. The PWM duty cycle can be varied from 0% to 100% by modulating the analog voltage on APWM from VRAMP(LOW) to VRAMP(HIGH). The PWM dimming frequency is internally set to typical value of 1.5 kHz. In addition, an external PWM input can control current by driving UDIM input. When both UDIM and APWM inputs are present, the internal PWM control command is derived by ANDing the two pulse width modulated signals. The APWM input can be tied to VCC to enable only external PWM control. Alternatively, APWM input can be biased using NTC to scale average LED current and enable temperature foldback protection of LEDs. This device optimizes the inductor current response and is capable of achieving over a 1000:1 PWM dimming ratio.
The device incorporates enhanced programmable fault features, including the following:
In addition, thermal shutdown (TSD) protection is implemented to limit the junction temperature at 175°C (typical).