Maxim > Design Support > Technical Documents > Subsystem Boards > APP 5827 Keywords: Petaluma MAXREFDES30, 16-bit 8-channel simultaneous-sampling analog front end SUBSYSTEM BOARD 5827 Petaluma (MAXREFDES30 ): 8-Channel Simultaneous- Sampling Analog Front End Apr 28, 2014 Abstract: The Petaluma (MAXREFDES30 ) subsystem reference design is a cost optimized, high-speed and high-accuracy analog measurement solution for three-phase power monitoring applications. Hardware, firmware, design files, and lab measurements provide complete system information for rapid prototyping and development. Introduction Three-phase power measurement applications require multiple analog inputs for voltage and current measurements on each line of the three-phase system. A power monitoring system must sample all of the analog inputs simultaneously to accurately calculate the instantaneous power consumption. The Petaluma (MAXREFDES30 ) subsystem reference design provides eight high-speed, 250ksps, 16-bit simultaneous-sampling analog input channels that accept 10V input signals. The Petaluma design utilizes two quadruple ultra-precision, ultra-low-noise input buffers (MAX44252) an 8-channel, 16-bit simultaneous-sampling ADC (MAX11046B) an ultra- high precision 4.096V voltage reference (MAX6126) and regulated +10V, -10V, and +5V power rails (MAX1659, MAX765/LM337, MAX8881). In addition to three-phase power measurement applications, this subsystem also performs well in any application that requires multiple More detailed image (JPG) simultaneous sampling of analog inputs, such as multiphase motor control and industrial vibration sensing. Page 1 of 10Figure 1. The Petaluma subsystem design block diagram. Features Competitive Advantages High precision, 8-channel, simultaneous-sampling inputs High-performance energy measurement subsystem Cost optimized High-speed 250ksps sampling rate Energy efficient High-accuracy 16-bit resolution Device drivers Example C source code Configuration files for ZedBoard platform FMC-compatible Applications Three-phase power measurement Power grid protection Multiphase motor control Vibration and waveform analysis Detailed Description of Hardware The Petaluma subsystem is optimized for applications that use multiple high-speed, high-accuracy, simultaneous-sampling analog inputs. Figure 1 shows the block diagram of the Petaluma reference design. The MAX44252 devices (U1 and U2) are quadruple ultra-precision, low-noise op amps. The op amps attenuate and buffer the 10V input signals to match the input range of the ADC (MAX11046). The MAX44252 devices are set up in the inverting configuration, so the polarity of the signal is reversed at the input of the ADC. The formula to convert the ADC code to voltage is: 10-CODE/65536*20. Page 2 of 10