SI8900-1 SILABS [Silicon Laboratories], SI8900-1 Datasheet - Page 22

• Manufacturer Part Number: SI8900-1
• Description: ISOLATED MONITORING ADC
• Manufacturer: SILABS [Silicon Laboratories]

Si8900/1/2
6.3. Application Example
Figure 17 shows the Si8900 operating as a single-phase ac line voltage and current monitor. The VDDA dc bias
circuit uses a low-cost 3.3 V linear regulator referenced to the neutral (white wire). The ac current is measured on
ADC input AIN0. The ac line voltage is scaled by resistors R17 and R18 and level-shifted by the 1.5 V VREF. AC
line current is measured using differential amplifier U1 connected across shunt resistor R1. Data is transferred to
the external controller or processor via the isolated UART.
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Single‐Phase
AC Line
R17
C1
R1
R18
R2
R7
R5
1.5 V
R12
R13
R8
D1
C4
R9
Figure 17. AC Line Monitor Application Example
R3
Dual OpAmp
Low Cost
3.3 V
R4
LDO
U2
U1
R10
1.5 V
C5
R14
R6
R11
R15
1.5 V
C3
C2
Rev. 1.0
AIN0
VDDA
GNDA
AIN1
Si8900
GNDB
VDDB
R
T
X
X
Master Controller
Output Side
Bias Supply
External