JAJSKS4A August 2021 – December 2021 TPS92519-Q1
PRODUCTION DATA
The adaptive on-time control technique enables parallel operation of two or more channels with independent current sharing and regulation. Each channel operates independently and delivers current based on the corresponding IADJx set point. To equally share current amongst channels, the IADJx for all channels must be connected to the external reference voltage.
Startup requires all channels to be enabled simultaneously by synchronizing the rising edge of IADJx voltage above VIADJx(SD) rising threshold. This simultaneous enabling ensures that the soft-start ramp is synchronized and current sharing is achieved after COMP voltage increases above the rising startup threshold, VCOMPx(ST).
PWM dimming is achieved by connecting the external PWM signal to UDIMx pin of all parallel channels. All parallel channels have to be controlled by single PWM dimming reference. TI does not recommend to PWM dim individual parallel channels.
Additional considerations are necessary to account for bootstrap capacitor tolerance and the impact of the capacitor variation when PWM dimming multiple parallel channels. Ensure that bootstrap capacitor voltage is above the undervoltage threshold, VBSTx(UV) for all operating conditions. For application requiring very low PWM duty cycle or low PWM dimming frequency, TI recommends to connect the COMPx pin of all parallel channels using nonparallel diodes, as shown in Figure 7-12. This connection allows the parallel channels to respond and recovery from bootstrap undervoltage fault when operating at low PWM dimming duty cycles.