VPS8701B

VPS8701B is a transformer driver specifically designed for micro-power isolated power supplies with small form factor and low standby power consumption. With only simple input/output filter capacitors, an isolation transformer, and a rectifier circuit as external components, it can implement an isolated power supply supporting 6~30V input voltage, multiple output voltages, and 1~2W output power. VPS8701B integrates two N-channel power MOSFETs and two P-channel power MOSFETs internally, configured in a full-bridge connection. The on-chip oscillator provides a pair of high-precision complementary signals, ensuring high symmetry of the two power MOSFET drive paths and preventing magnetic flux imbalance during operation. VPS8701B integrates frequency synchronization and multiple protection features. When an external clock signal is applied to the CLK pin, VPS8701B outputs two complementary drive signals at half the external clock frequency. An internal high-precision dead-time control circuit ensures shoot-through is prevented under all operating conditions. Integrated overcurrent protection and over-temperature protection safeguard the device against damage caused by output short circuits and other abnormal conditions. VPS8701B is a full-bridge topology DCDC isolated switching power supply integrated controller. The full-bridge drive configuration requires fewer transformer windings and reduces cost. It supports 6V~30V applications with strong compatibility. When the current is excessive, a clamp limits the power transistor current, ensuring the chip operates within its safe operating area while protecting peripheral components from high-current stress. The operating frequency can be selected via the CLK pin: left floating for low-frequency fSW0, pulled to GND for high-frequency fSW1. The CLK pin also accepts an external synchronization clock signal, in which case the output frequency is half the clock frequency. A dead-time tBBM is implemented between the two drive outputs to prevent shoot-through while reducing the drain-source voltage at power transistor turn-on and minimizing switching losses. The chip can be enabled or disabled via the EN pin. When EN is pulled high (internally pulled high when floating), the chip operates normally. When EN is pulled low, the chip shuts down, achieving ultra-low standby power consumption.

Applications

• Low-power isolated power supply for CAN/RS-485/RS-232/SPI/I²C
• Process control
• Precision instruments/medical instruments
• Distributed power/radio power/telecom power
• Low-noise isolated USB power supply
• Low-noise filament power supply
• IGBT gate drive power supply

Key features

• Full-bridge topology
• High integration, minimal external components
• Integrated 30V / 0.25Ω NMOS
• Integrated 30V / 0.60Ω PMOS
• 0.45A current clamp limit
• 6 - 30V input voltage range
• Input transient voltage up to 38V
• Frequency synchronization and built-in selectable frequency
• Enable shutdown function
• Built-in soft-start
• Continuous short-circuit protection, over-temperature protection, auto-recovery
• Operating temperature range: -40°C ~ +125°C