PL5501 module

 PL5501 module technical parameters

Rated input voltage: 24V

Rated output current: 10A

Output mode: four-tube boost and buck

Control mode: digital given, analog control

1. PL5501 module technology path

1. Buck-boost implementation    PL5501 is a synchronous 4-switch buck-boost controller launched by Baoli Microelectronics, which can adjust the output voltage to be higher or lower than the input voltage. The PL5501 operates over a wide input voltage range of 3.6V to 32V (36V maximum) to support a variety of applications; the PL5501 uses constant on-time control in buck, boost and buck-boost operating modes for excellent load and line regulation. Depending on the resistor value between the FREQ pin and the GND pin, the switching frequency can be set to 150kHz, 300kHz, 600kHz or 1200kHz. The device also features programmable soft-start and offers various protection features including cycle-by-cycle current limit, input undervoltage lockout (UVLO), output overvoltage protection (OVP), input overvoltage protection, thermal shutdown and output Short circuit protection, etc.; VADJ and IADJ pins are used to program the output VBUS voltage and output current limit, providing voltage control loop, constant current loop, thermal regulation loop, temperature sensing and other functions. The main topology uses AON6144 MOS tubes, flat copper-wound inductors, and solid capacitors to achieve better parameters in a smaller volume and control the temperature rise under high current to a reasonable limit.

2. Analog control    This design uses a current sensing resistor to sample the input and output current to achieve closed-loop control of the current; the output voltage uses a combination of voltage dividing resistor + mirror constant current source to achieve virtual adjustment of the lower voltage dividing resistor, making the output The voltage can be adjusted as needed, the duty cycle control is implemented using the chip's internal regulator, and the control part is purely analog mode.

3. The digital reference     controls the voltage reference pin of the mirror constant current source through a high-precision DAC, causing the feedback voltage of the voltage dividing resistor + mirror constant current source adjustment combination to change, thereby achieving voltage regulation; the microcontroller collects the output at the V2 node through the ADC The voltage is compared with the given value, and the error is sent to the digital PID regulator. The regulator output controls the DAC to realize the digital given output voltage and digital closed loop; since the fixed voltage dividing node V2 is compared with the given value, this structure It has extremely high readback characteristics, which greatly optimizes the load regulation rate.

2. Test conclusion

        When the input voltage is 24V, a 10A constant current load is connected, and the test output voltage is set to 3.3V. After continuous operation for 1 hour, there is no obvious overheating phenomenon. The output voltage drift is not measured when using a three-and-a-half-digit digital multimeter at the 6V voltage range. output drift. Using a digital oscilloscope with 100MHz bandwidth and 1G/s sampling rate, and the test channel settings are: AC coupling, X1, 20MHz bandwidth limit, 20mV/div, the measured power supply ripple is less than 20mVpp.

Figure 1 Output ripple of the module

Figure 2 Switch tube waveform

Figure 3 Static power consumption