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PDF Si8920 Data sheet ( Hoja de datos )
| Número de pieza | Si8920 | |
| Descripción | ISOLATED AMPLIFIER | |
| Fabricantes | Silicon Laboratories | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de Si8920 (archivo pdf) en la parte inferior de esta página. Total 22 Páginas | ||
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Si8920
ISOLATED AMPLIFIER FOR CURRENT SHUNT MEASUREMENT
Features
Low voltage differential input
±100 mV and ±200 mV options
Low signal delay: 0.75 µs
Input offset: 0.2 mV
Gain error: <0.5%
Excellent drift specifications
1 µV/°C offset drift
60 ppm/°C gain drift
Nonlinearity: 0.1% full-scale
Low noise: 0.10 mVrms over
100 kHz bandwidth
High common-mode transient
immunity: 75 kV/µs
Compact packages
16-pin wide body SOIC
8-pin surface mount DIP
–40 to 125 °C
AEC-Q100
Applications
Industrial, HEV and renewable
energy inverters
AC, Brushless, and DC motor
controls and drives
Variable speed motor control in
consumer white goods
Isolated switch mode and UPS
power supplies
Safety Approvals (Pending)
UL 1577 recognized
Up to 5000 Vrms for 1 minute
CSA component notice 5A
approval
VDE certification conformity
VDE0884 Part 10
(basic/reinforced insulation)
CQC certification approval
GB4943.1
Description
The Si8920 is a galvanically isolated analog amplifier. The low-voltage
differential input is ideal for measuring voltage across a current shunt
resistor or for any place where a sensor must be isolated from the control
system. The output is a differential analog signal amplified by either 8.1x
or 16.2x.
The very low signal delay of the Si8920 allows control systems to respond
quickly to fault conditions or changes in load. Low offset and gain drift
ensure that accuracy is maintained over the entire operating temperature
range. Exceptionally high common-mode transient immunity means that
the Si8920 delivers accurate measurements even in the presence of high-
power switching as is found in motor drive systems and inverters.
The Si8920 isolated amplifier 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.
Ordering Information:
See page 14.
Pin Assignments
VDDA 1
AIP 2
AIN 3
GNDA 4
Si8920
8 VDDB
7 AOP
6 AON
5 GNDB
VDDA 1
AIP 2
AIN 3
GNDA 4
NC 5
NC 6
NC 7
GNDA 8
16 GNDB
15 NC
14 VDDB
13 AOP
Si8920
12 NC
11 AON
10 NC
9 GNDB
Patents pending
Preliminary Rev. 0.5 8/15
Copyright © 2015 by Silicon Laboratories
Si8920
This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
1 page  
2. Electrical Specifications
Si8920
Table 1. Electrical Specifications
VDDA, VDDB = 5 V, TA = –40 to +125 °C; typical specs at 25 °C
Parameter
Input Side Supply Voltage
Input Supply Current
Output Side Supply Voltage
Output Supply Current
VDD Undervoltage Threshold
Symbol
VDDA
IVDDA
VDDB
IVDDB
VDDUV+
Test Condition
Min Typ Max
3.0 5.5
VAIP = VAIN @ 3.3 V
3.2
3.0
4.2
5.5
5.5
VAIP = VAIN @ 3.3 V
VDDA, VDDB rising
2.3
3.2
2.7
4.1
VDD Undervoltage Threshold
VDDUV–
VDDA, VDDB falling
2.6
VDD Undervoltage Hysteresis
Amplifier Bandwidth
VDDHYS
100
750
Amplifier Input
Specified Full Scale Si8920A
Input Amplitude
Si8920B
VAIP – VAIN
–100
–200
100
200
Maximum Input Volt- Si8920A
age Before Clipping Si8920B
VAIP – VAIN
±125
±250
Common-Mode Operating
Range
VCM
–0.2 1
Input referred offset
VOS
0.2 1.5
Input offset drift
Differential Input
impedance
Si8920A
Si8920B
VOST
RIN
1.0
20
37.2
Amplifier Output
Full-scale Output
VAOP – VAON
1.58 1.62 1.65
Gain
Si8920A
16.2
Si8920B
8.1
Gain Error
Gain Error Drift
TA = 25 °C
–0.5
60
0.5
Output Common Mode Voltage (VAOP + VAON)/2
1.02 1.1
1.17
Output Noise
Si8920A
100 kHz bandwidth
0.14 0.28
Si8920B
100 kHz bandwidth
0.10 0.20
Nonlinearity
Si8920A
Si8920B
0.15 0.50
0.10 0.30
Output Resistive Load
Output Capacitive Load
Timing
RLOAD
CLOAD
5
100
Signal Delay
tPD 50% to 50%
50% to 99%
10% to 90%
0.75
1.85
0.42
Common-Mode Transient
Immunity*
CMTI
AIP = AIN = AGND,
VCM = 1500 V
50
75
*Note: An analog CMTI failure is defined as an output error of more than 100 mV persisting for at least 1 µs.
Units
V
mA
V
mA
V
V
mV
kHz
mV
mV
mV
mV
V
mV
µV/°C
k
k
Vpk
%
ppm/°C
V
mVrms
mVrms
%
%
k
pF
µs
kV/µs
Preliminary Rev. 0.5
5
5 Page 
Si8920
4. Functional Description
The input to the Si8920 is tuned for low-voltage, differential signals. This is ideal for connection to low resistance
current shunt measurement resistors. The Si8920A has a full scale input of ±100 mV, and the Si8920B has a full
scale input of ±200 mV. In both cases, the internal gain is set so that the full scale output is 1.6 V.
The Si8920 modulates the analog signal in a unique way for transmission across the semiconductor based
isolation barrier. The input signal is first converted to a pulse-width modulated digital signal. For transmission
across the isolation barrier, the signal is further modulated with a high frequency carrier. On the other side of the
isolation barrier, the signal is demodulated and the carrier portion is removed. The resulting PWM signal is then
used to faithfully reproduce the analog signal. This solution provides exceptional signal bandwidth and accuracy.
5. Current Sense Application
High Voltage
Bus
Floating
Low Side
Gate Driver Gate Driver
24V Supply Supply
3.3 to 5V
Supply
Q1
RSENSE
Load
Q2
R3
1.82K
Q3
C3
0.1uF
D1
5.6V
C2
0.1uF
R1 20
C1
10nF
R2 20
VDDA
VOA
GNDA
VDDB
VOB
GNDB
PWM
VDDI
GNDI
DISABLE
DT
VDDI
Si8234
C5
0.1uF
R6
1
VDDA
2
AIP
3 AIN
4 GNDA
Si8920
VDDB
AOP
AON
GNDB
8
7
6
5
C4
0.1uF
R4
C6
R5
To
Controller
+
ADC
‐
Figure 9. Current Sense Application
In the driver circuit presented in Figure 9, the Si8920 is used to amplify the voltage across the sense resistor,
RSENSE, and transmit the analog signal to the low voltage domain across an isolation barrier. Isolation is needed
as the voltage of RSENSE with respect to ground will swing between 0 V and the high voltage rail connected to the
drain of Q1.
The load in this application can be a motor winding or a similar inductive winding. In a three phase motor drive
application, this circuit would be repeated three times, one for each phase. RSENSE should be a small resistor
value to reduce power loss. However, too low a resistance will reduce the signal-to-noise of the measurement.
Si8920 offers two specified full scale input options, ±100 mV (Si8920A) and ±200 mV (Si8920B) for optimizing the
value of RSENSE.
AIP and AIN connections to the RSENSE resistor should be made as close as possible to each end of the
RSENSE resistor as trace resistance will add error to the measurement. The input to the Si8920 is differential, and
the PCB traces back to the input pins should run in parallel. This ensures that any large noise transients that occur
on the high voltage side are coupled equally to the AIP and AIN pins and will be rejected by the Si8920 as a
common-mode signal.
Preliminary Rev. 0.5
11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet Si8920.PDF ] | |
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