Typical application circuit of CP2131

CP2131 is a parallel white LED driver chip that can adaptively select the 1x voltage or 1.5x voltage operating mode based on the power supply voltage and the conduction voltage drop of the white LED to ensure that the chip operates within the entire lithium-ion battery operating voltage range. high efficiency. The new Auto-Mirror technology makes the current matching degree of each parallel white LED almost unchanged with the difference in the conduction voltage drop of the white LED. Under typical circumstances, the current matching of white LEDs can be as high as 0.5%. Using CP2131 to form a white LED drive circuit only requires four ceramic capacitors, which is very suitable for battery power applications in portable electronic devices. CP2131 adopts non-shutdown mode PWM dimming method to set the brightness of white LED, and the dimming rate can be as high as 50kHz. At the same time, in startup and dimming modes, CP2131 can ensure relatively small input current fluctuation and low EMI. CP2131 has a shutdown mode, and the shutdown current is less than 0.1 microampere. The main technical characteristics of CP2131 are as follows.
① Drive up to 3 LEDs, the maximum current of each LED is 30mA.
②Current matching accuracy is 0.5% (typical value).
③Using Auto-Mirror technology to ensure improved current matching when the conduction voltage difference between parallel white LEDs is large.
④ The high-efficiency 1x voltage and 1.5x voltage modes can be adaptively switched according to the input voltage and load conditions, with efficiency as high as 90%.
⑤Supports PWM (frequency range: 0~50kHz) brightness adjustment method.
⑥Small input current fluctuation and low EMI.
⑦ No external inductor is required.
⑧The switching frequency is 1MHz.
⑨With overcurrent protection and overheating protection functions.
⑩The operating voltage range is 2.7~5.5V, and it is packaged in a tiny 3∏m×3mrn QFN 1 6L package.
Regarding the efficiency issue of concern, CP2130, CP2131 and CP2133 implement adaptive dynamic switching of two working modes (i.e. judged based on the battery voltage and the actual LED conduction voltage drop) instead of fixed voltage point switching (i.e. only considering the battery voltage). It is possible to make the charge pump work in 1x voltage mode, thus significantly improving efficiency.