BL0937B

BL0937  FEATURES            Single Phase Energy Meter IC with Integrated Oscillator for plug  DESCRIPTION High accuracy, less than ± 0.5% error over a dynamic range of 2500: 1 High stability of large signal, in the condition of signal 300mA, less than ± 0.2% error in the output frequency fluctuation (CF). High stability of small signal, in the condition of signal 50mA, less than ± 0.3% error in the output frequency fluctuation (CF). Current and voltage RMS, current measurement range (4mA ~ 30A) @ 1mohm On-Chip anti-creep protection On-Chip power supply detector On-Chip voltage reference of 1.2V On-chip oscillator as clock source, 2MHz Single 3.3V supply, low power (6 mW typical) SOP8 BL0937 is a wide range of single-phase multi-function energy meter IC for single-phase plug, Smart Appliance, with a low cost and high accuracy. BL0937 integrates two high-accuracy Sigma-Delta ADC, voltage reference, power management and other analog circuit modules, and digital signal processing circuit to calculate active power, IRMS, VRMS etc. High frequency CF1 is provided for indicating IRMS/VRMS and high frequency CF for energy metering. BL0937 can measure the single-phase active energy, active power, current and voltage RMS and other parameters to fully meet the needs of the socket, plug row, smart appliances and others. Interrelated patents are pending. BLOCK DIAGRAM VDD Power On/Reset Internal Clock 1 IP 2 IN 3 VP 4 BL0937 VDD 8 SEL 7 CF1 6 CF 5 GND IP IN PGA ADC RMS DSP VP PGA Reference Voltage SOP8 WATT ADC Voltage to Frequency Converter SEL CF1 CF 1.25V BL0937 GND  PIN DESCRIPTIONS Pin Symbol DESCRIPTIONS 1 VDD Power Supply (+3.3V). Provides the supply voltage for BL0937 It should be maintained at 3.0V~3.6V when IC is working http://www.belling.com.cn -1Total 6 Pages 12/14/2016 BL0937 Single Phase Energy Meter IC with Integrated Oscillator for plug IP,IN Inputs for Current Channel. These inputs are fully differential voltage inputs with a maximum signal range of ±50 mV. Because of the internal ESD protection circuit, If the voltage exceeds ±1.5V the IC will not be damaged badly. 4 VP Positive Input for Voltage Channel. The Voltage Inputs is differential voltage inputs with a maximum signal range of ±200 mV. Because of the internal ESD protection circuit, If the voltage exceeds ±1.5V the IC will not be damaged badly. 5 GND 2,3 Ground Reference. CF High frequency pulse output for active power, the pulse width is fixed to 38uS; the frequency is proportional to the active power value. Over-current indication pin; If over-current occurs, the pin output 6.78KHz pulse. 7 CF1 SEL=0, the output is current RMS, pulse width is fixed to 38uS, The frequency is proportional to the current RMS value; SEL=1, the output is voltage RMS, pulse width is fixed to 38uS, The frequency is proportional to the voltage RMS value; 8 SEL RMS output select. 6  Package Dimensions SOP8  ABSOLUTE MAXIMUM RATINGS ( T = 25 ℃ ) Parameter Symbol Value Unit Power Voltage VDD VDD -0.3 ~ +4 V Analog Input Voltage to GND IP、IN、VP -4 ~ +4 V Digital Input Voltage to GND SEL -0.3 ~ VDD+0.3 V Digital Output Voltage to GND CF、CF1 -0.3 ~ VDD+0.3 V http://www.belling.com.cn -2Total 6 Pages 12/14/2016 Single Phase Energy Meter IC with Integrated Oscillator for plug BL0937 Operating Temperature Range Topr -40 ~ +85 ℃ Storage Temperature Range Tstr -55~+150 ℃ Power Dissipation(SOP8) P 10 mW  ELECTRONIC CHARACTERISTIC PARAMETER (VDD=3.3V,GND=0V,On-Chip voltage reference, 2MHz crystal oscillator, Room temperature) Parameter Power Supply Power Dissipation Symbol Test Condition Measure Pin Typical Value 3.0 VDD Iop Min Value VDD=3.3V Max Value Unit 3.6 V 3 mA Measure Error on Active Power(Absolute error) WATTerr a dynamic range 2500 to 1 CF 0.3 0.5 % Measure fluctuation error on Active Power(Large signal) Δ@6%Ib, 300mA@1mohm, CF 0.1 0.2 % Measure fluctuation error on Active Power(Small signal) Δ@1%Ib, 50mA@1mohm, CF 0.15 0.3 % 0.5 % 0.5 % Ib=5A Ib=5A Phase error when PF=0.8 Capacitive PF08err Phase error when PF=0.5Inductive PF05err Current lead 37°（PF=0.8） Current lags 60°（PF=0.5） AC PSRR ACPSRR IP/N=100mV 0.1 % DC PSRR DCPSRR VP/N=100mV 0.1 % Vrms measurement Error VRMSerr CF1 0.3 % Irms measurement Error IRMSer CF1 0.3 % Analog Input Voltage(current) Current differential 50 mV 200 mV input (peak) Analog Input Voltage(voltage) voltage differential input (peak) Analog Input Impedance VP/IP/IN 370 kΩ SEL pull-down resistance SEL(pull-down) 80 kΩ Input Signal Bandwidth (-3dB) 3.5 kHz 1.218 V On-chip voltage reference VREF Vref Input High Voltage VDD=3.3V± 5% Input Low Voltage VDD=3.3V± 5% Output High Voltage VDD=3.3V± 5% 2.6 V 0.8 V V VDD-0.5 IOH=5mA Output Low Voltage VDD=3.3V± 5% 0.5 V IOH=5mA Over-current threshold http://www.belling.com.cn Current sampling -3Total 6 Pages 36 A 12/14/2016 BL0937 Single Phase Energy Meter IC with Integrated Oscillator for plug resistor 1mΩ the frequency of over-current 6.7 kHz response time of Over-current 200  THEORY OF OPERATION  Principle of Energy Measure In energy measure, the power information varying with time is calculated by a direct multiplication of the voltage signal and the current signal. Assume that the current signal and the voltage signal are cosine functions; V and I are the peak values of the voltage signal and the current signal; ω is the angle frequency of the input signals; the phase difference between the current signal and the voltage signal is expressed asФ. Then the power is given as follows: p(t )  V cos(wt )  I cos(wt  )  =0: p(t )    0: VI (1  c o s2(wt ) 2 p(t )  V cos( wt )  I cos( wt  )  V cos( wt )  I cos( wt ) cos()  sin( wt ) sin() VI (1  cos(2wt )) cos()  VI cos( wt ) sin( wt ) sin() 2 VI VI  (1  cos(2wt )) cos()  sin( 2wt ) sin() 2 2  p(t) is called as the instantaneous power signal. The ideal p(t) consists of the dc component and ac component whose frequency is 2ω . The current and voltage signals are sampled with high precision and converted from analog signals to digital signals. The instantaneous power signal p(t) is obtained after the digital signals are calculated by digital multiplier. In order to extract the real power component (i.e., the dc component), the instantaneous power signal is low-pass filtered, and then accumulated (e.g., by a counter) to generate real energy information. These information is sent to the digital-to-frequency converter module, and converted to a pulse signal of the certain frequency which is proportional to the real power. Similarly, the voltage and current RMS are calculated and then sent to the digital-to-frequency converter module, converted to a pulse signal of the certain frequency which is proportional to the voltage and current RMS.  Power Supply Monitor BL0937 contains an on-chip power supply monitor. The power supply (VDD) is continuously monitored by BL0937. if the supply is less than 2.7V±5%, BL0937 will be reset. This is useful to ensure correct device startup at power-up and power-down. The power supply monitor has built in http://www.belling.com.cn -4Total 6 Pages 12/14/2016 ms BL0937 Single Phase Energy Meter IC with Integrated Oscillator for plug hysteresis and filtering. This gives a high degree of immunity to false triggering due to noisy supplies. Under normal circumstances, the decoupling part of power supply should ensure that the ripple on VDD does not exceed 3.3V ±5%.  CHIP APPLICATIONS  Typical Application BL0937 Typical application block diagram is shown below. Single 3.3V supply. The current signal is sampled through the alloy resistor connected to the IP and IN pins of BL0937. The voltage signal is sampled through the resistor divider network connected to the VP pin of BL0937. CF, CF1, SEL directly access to the MCU pin. CF/CF1 pulse cycle is measured to calculate the power, current RMS and voltage RMS. N L 220V  3.3V  DC AC 510 VDD IP 68nF IN 510 68nF VP SEL CF1 MCU CF GND 330k 6800P 330k 330k 22nF 330k 330k http://www.belling.com.cn 510 330k LOAD BL0937 Alloy resistor 1mΩ -5Total 6 Pages 12/14/2016 BL0937 Single Phase Energy Meter IC with Integrated Oscillator for plug  CF、CF1 frequency BL0937 calculates the product of two voltage signals (on current channel and voltage channel) and then low-pass filters this product to extract real power information. This real power information is then converted to a frequency. The frequency information is output on CF in the form of active high pulses. At the same time current RMS and voltage RMS are calculated and converted to a frequency, and output on CF1 in the form of active high pulses. （1）active power pulse frequency formula： FCF = 1721506 * V(V)*V(I) Vref2 （2）voltage RMS pulse frequency formula： FCFU = 15397 * V(V) Vref （3）current RMS pulse frequency formula： FCFI = 94638 * V(I) Vref V(V)——the voltage RMS of the voltage channel V(I)——the voltage RMS of the current channel Vref——reference voltage（1.218V）  Anti-creep BL0937 has a patented anti-creep design with a reasonable external hardware design to ensure that the noise power is not included in the energy pulse in the absence of current. The anti-creep threshold is 0.0035% of the active power corresponding to the full-scale input signal.  Over-current detection BL0937 has fast over-current detection function. BL0937 can detect the over-current within 200ms. The pin CF would output over-current signal when over-current occurs. This function helps to design the over-current protection circuit.  Current/voltage RMS output The current / voltage RMS is output from the pin CF1. When SEL = 0, the CF1 outputs a high frequency pulse of the current RMS; When SEL = 1, the CF1 outputs a high frequency pulse of the voltage RMS. The current and voltage RMS calculation modules of BL0937 are separate internally. SEL switching time < 10uS. http://www.belling.com.cn -6Total 6 Pages 12/14/2016