This page introduces Si89xx series analog isolation (Isolation Amp) products with built-in isolation and amplifier functions.
Product Summary
The Si89xx series is a series of isolation devices that can transfer analog signals (current/voltage values) on the primary (input) side to the secondary (output) side while maintaining isolation. This allows the HOST IC to safely monitor analog signals (current/voltage values) on the primary (input) side through isolation. There are IsoAmp (Si892x) that outputs an analog signal with a fixed magnification, and an isolated sigma-delta modulator (Si894x) that sends an analog signal digitized by a sigma-delta ADC. We have a lineup for both single-ended and differential input types.
Accurate current and voltage measurements are essential for the correct operation of power control systems such as motors and power supplies. Applications that need to maximize system efficiency and respond quickly to faults and load changes call for these products.
Product features
Compared to other insulation products such as photocouplers, it minimizes the number of external parts, reduces characteristic fluctuations such as gain error due to temperature characteristics and aging, and can stably send signals to the secondary side. .
- Small offset and gain errors Small temperature drift Easy to design
- High dielectric strength UL1577 5Kvrms ±10KV surge withstand
- High Common Mode Rejection Ratio (CMTI) 50kV/us (min) 75KV/us (typ)
- Compact and highly compatible package lineup with few external devices: stretch SO8 package (Si893x, Si894x) and Gall-wing Dip8 WB SOIC16 (Si892x)
- Compatible ±62.5mV and ±250mV input ranges for current measurements and wide 2.25V input range for voltage measurements
- It has a Fail Safe function that can detect power loss on the input side.
- Short delay time (IsoAmp si893x: 1us typ)
- high SNR
Product lineup
Differential Input Isolated Amplifier Si892x
There are differential input/differential output type isolation amplifiers (Si8920, Si8921) and differential input single-ended output isolation amplifier Si8922 that can be used to detect motor phase currents.
±100mV, ±200mV input
Gull-Wing DIP-8
±62.5mV, ±250mV input
WB stretched SOIC-8/NB SOIC-8
8 - 62.5mV/ 30 - 250mV single-ended output
WB stretched SOIC-8/NB SOIC-8
Single-ended input type isolation amplifier Si893x
Single-ended input isolation amplifier. Since the input impedance is high, a high resistance value of ≤10KΩ can be used for the detection resistor. The output line-up includes differential output (Si8931) and single-ended output (Si8932).
Single-Ended Input Sigma-Delta Module Si893x
This is a single-ended input delta-sigma modulator. There are external clock synchronous type (Si8935) and internal clock type (Si8936, Si8937).
External CLK input (~20MHz)
Internal clock 10MHz
Internal clock 20MHz
Differential Input Sigma-Delta Module Si894x
This is a differential input delta-sigma modulator. There are external clock synchronous (Si8941) and internal clock (Si8946, Si8947) types.
External CLK input (~20MHz)
Internal clock 10MHz
Internal clock 20MHz
| part number | input | output | Input range | Insulation rating | Package |
| Si8920 | 1ch differential input | Differential analog output | ±100/±200mV | 3.75/5kVrms | Gull-wing DIP-8 /WB SOIC-16 |
| Si8921 | 1ch differential input | Differential analog output | ±62.5/±250mV | 2.5/5kV rms | NB SOIC-8/WB Stretched SOIC-8 |
| Si8922 | 1ch differential input | Single-ended analog output | 8 to 62.5mV/ 30 to 250mV | 2.5/5kV rms | NB SOIC-8/WB Stretched SOIC-8 |
| Si8931 | 1ch single-ended input | Differential analog output | 0~2.5V | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| Si8932 | 1ch single-ended input | Single-ended analog output | 0~2.5V | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| Si8935 | 1ch single-ended input + clock input | ΣΔ digital output | 0~2.5V | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| Si8936 | 1ch single-ended input | ΣΔ digital output + 10MHz clock output | 0~2.5V | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| Si8937 | 1ch single-ended input | ΣΔ digital output + 20MHz clock output | 0~2.5V | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| Si8941 | 1ch differential input + clock input | ΣΔ digital output | ±62.5/250mV | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| SI8946 | 1ch differential input | ΣΔ digital output + 10MHz clock output | ±62.5/250mV | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
| SI8947 | 1ch differential input | ΣΔ digital output + 20MHz clock output | ±62.5/250mV | 2.5/5kV rms | NB SOIC-8 /WB Stretched SOIC-8 |
Please refer to each data sheet for details.
application
Can be used for BMS (battery monitoring system) voltage monitor and current monitor. In the figure on the left, the blue boxes are the voltage monitor Iso Amp, SI8931, 32, etc. The orange boxes are the current monitor Iso Amp Si892x.
It can be used for input and output voltage monitor and current monitor in On-Board Charger System (OBC).
It can be used for accurate detection using a detection resistor in a motor driver such as a servo motor or a monitor of each phase current such as a power supply circuit.
Related information
Brochure: Isolation in Electric Vehicle Systems
Isolation Product Selector Guide
Application Note:
AN1270: Estimating Total Static Error for Skyworks Si89xx Isolated Amplifiers and Delta-Sigma Modulators
AN1215: SINC3 Filter for DSM Applications
Datasheet:
Si8920: Isolated Amplifier for Current Shunt Measurement
Si8921/22: Isolated Amplifier for Current Shunt Measurement
Si8931/32: Isolated Amplifier for Voltage Measurement
Si8935/36/37: Delta-Sigma Modulator for Voltage Measurement
Si8941/46/47: Isolated Delta-Sigma Modulator for Current Shunt Measurement
User Guide
UG383: Si89xx-EVB User's Guide
Tools & Software
ISOLATION BOOSTRAP CAPACITOR: A web-based calculator for bootstrap capacitors.
ISOLATOR POWER CONSUMPTION CALCULATOR: A web-based power loss calculator for isolator devices.
Evaluation Board
Si8921 Isolated Amplifier Evaluation Kit
si8921iso-kit: Si8921 Isolated Amplifier Evaluation Kit
Similarly, there are evaluation boards for the Si8922, Si8931, Si8932, Si8935, Si8936, Si8941, Si8946, and Si8947.
See UG383 (Si89xx-EVB User's Guide) for more information on the evaluation board.
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