BL BA7755

The BA7755 IC is the core metering chip for electronic energy meters. Its design employs oversampling and digital signal processing techniques, which significantly improves measurement accuracy. All data following A/D conversion is processed and computed by digital circuitry, ensuring long-term stability. Electronic energy meters designed around this chip feature simple peripheral circuitry, high accuracy, and excellent stability, making them suitable for energy metering in single-phase two-wire power consumers. The BA7755 can measure both forward and reverse active power. It converts reverse active power into pulse outputs aligned with the forward active power direction, while simultaneously providing a reverse power consumption indicator on Pin20. As a result, electronic energy meters built with the BA7755 offer strong anti-tamper and anti-theft capabilities. The BA7755 provides two pulse outputs at different frequencies. Pin22 outputs high-frequency pulses for calibration and computer data processing, while Pin23 and Pin24 output a set of lower-frequency pulses for directly driving a stepper motor to actuate the register for cumulative energy measurement. The BA7755 fully addresses the conflicting requirements of creep prevention and starting performance in energy meters. A well-designed digital anti-creep threshold is implemented to reliably prevent creeping while ensuring the starting current remains well below the standard requirement.

• High accuracy: non-linearity measurement error less than 0.1% over input dynamic range (500:1)
• High stability during meter calibration: output frequency fluctuation less than 0.1%
• Precise measurement of active power in both positive and negative directions, with energy calculated in the same direction
• Variable current channel gain; small shunt resistors can be used at the current channel input
• Slow output pulses for direct motor drive; fast output pulses for computer data processing
• Anti-tamper function: logic output pin REVP indicates reverse or incorrect power consumption
• On-chip voltage detection circuit for power-loss detection
• Anti-creep function
• On-chip reference voltage source 2.42V ±8% (typical temperature coefficient 30ppm/°C); external voltage source also supported
• Single supply voltage 5V
• Low power consumption 15mW (typical)
• 0.35um CMOS process for improved batch consistency and product reliability