Introduction
FP5207B is a non-synchronous boost control IC. It controls the external NMOS through EXT Pin, input low start-up voltage 2.8V and wide working voltage 5V~24V, single-cell lithium battery 3V~4.2V application, connect Vout to HVDD Pin; precise feedback The voltage is 1.2V, the soft start time is adjusted by an external capacitor, and the operating frequency is adjusted by an external resistor; overcurrent protection, the peak current of the inductor is detected, and the detection resistor Rcs is connected between the NMOS Source terminal of the switch and the ground.
1. Features
➢ Starting voltage 2.8V
➢ Working voltage range 5V~24V
➢ Feedback voltage 1.2V (±2%)
➢ Shutdown current consumption is less than 3μA
➢ Adjustable working frequency 100kHz~1000kHz
➢ Adjustable soft start time
➢ Input undervoltage protection (UVP)
➢ Adjustable over-current protection (OCP)
➢ Over Temperature Protection (OTP)
➢ Package DFN-10L(EP)
2. Market application
1. Application scope
➢ Bluetooth audio
➢ Charger
➢ Mobile power
➢ Portable products
2. Application circuit
Application components
➢ C1, C7: Input and output voltage stabilizing capacitors.
➢ C2, C6, C8: high-frequency noise filter capacitors.
➢ C3: Connect the input power supply to HVDD and generate 8V through the internal voltage regulator tube to VDS. This voltage will provide the internal circuit and EXT Pin
To drive the gate of the external Q2, a voltage stabilizing capacitor is required.
➢ C4, C5, C13, R1, R5: the compensation loop of the system, which is related to the stability of the system.
➢ C17: Soft-start capacitor, change the capacitor value to adjust the start-up time.
➢ L1: The inductance has the functions of energy storage and filtering. The larger the inductance value, the smaller the inductance ripple, and the smaller the relative inductance value, the larger the ripple. Choose inductance
Pay attention to whether the inductor is suitable for high-frequency operation, and the rated saturation current value of the inductor.
➢ D1: When Q2 is cut off, the D1 Schottky transistor is turned on to provide an inductor discharge circuit.
➢ Q2: Use NMOS with low internal resistance, the high voltage of the Drain terminal is equal to the output 19V, and the withstand voltage is 1.5 times of 19V.
➢ R3: Connect 200kΩ between Vin and EN to start the IC automatically.
➢ R6: Adjust the working frequency resistor.
➢ R11, R12: divider resistors to set the output voltage.
➢ R8: Reserved as an EMI countermeasure.
➢ Rcs: inductor peak current detection and overcurrent protection resistor.
Layout suggestion
Precautions:
➢ The wiring of the high current path should be thick, and the copper laying wiring is the best.
➢ Switch the connection point L1, Drain terminal of Q2 and D1, the wiring should be short and thick, copper laying wiring is the best.
➢ The input capacitor C6 is close to the HVDD and GND pins to achieve voltage regulation and filtering.
➢ The voltage divider resistor R11/R12 is close to the FB and GND pins.
➢ Keep the FB Pin away from the Drain and D1 of the switching points L1 and Q2 to avoid interference.
➢ The ground of the input capacitor C1/C2, the ground of the output capacitor C7/C8 and Rcs, lay copper wires, and connect the upper and lower layers with holes.
➢ The ground of the output capacitor C7/C8 must be close to the ground of Rcs, which can reduce the switching surge and output high-frequency noise.
➢ Rcs is close to CS and GND pins.
➢ It is recommended to pave the excess space on the board.