Si8935/36/37 Data Sheet
Delta-Sigma Modulator for Voltage Measurement
KEY FEATURES The Si8935/36/37 is a galvanically isolated delta-sigma modulator optimized for voltage sensing. Its 2.5 V input range is ideal for isolated voltage sensing applications. The Si8935/36/37
provides excellent linearity with low offset and gain drift to ensure that accuracy is maintained
over the entire operating temperature range. Exceptionally high common-mode transient immunity means that the Si8935/36/37 delivers accurate measurements even in the presence of
high-power switching as is found in motor drive systems and inverters.
The output of the Si8935/36/37 comes from a second-order, delta-sigma modulator. The modulator can be clocked either from an onboard oscillator (Si8936/37) or from an external clock
(Si8935). The output is typically digitally filtered by a MCU or FPGA in the system.
The Si8935/36/37 isolated delta-sigma modulator utilizes Silicon Labs’ proprietary isolation
technology. It supports up to 5.0 kVrms withstand voltage per UL1577. This technology enables
higher performance, reduced variation with temperature and age, tighter part-to-part matching,
and longer lifetimes compared to other isolation technologies. • 0 to 2.5 V nominal input voltage
• Modulator clock options
• External clock up to 25 MHz
(Si8935)
• 10 MHz internal clock (Si8936)
• 20 MHz internal clock (Si8937)
• Typical input offset: ±0.6 mV
• Typical gain error: ±0.1%
• Excellent drift specifications
• 1 µV/°C typical offset drift
• 30 ppm/°C typical gain drift
• Typical nonlinearity: 0.02% …
