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3.2 Bill of materials
Table 3.1 shows a bill of materials for the voltage-sensing circuit using the TLP7820
Table 3.1 Bill of materials for the voltage-sensing circuit using the TLP7820
No.
Ref.
1
IC1
2
IC2
R1
３
4
R2
R3
５
6
R4, R5, R6, R7
7
R8, R9
8
C1
9
C2, C3, C6
10
C4, C5
11
C7
4. Guidelines for designing a voltage-sensing circuit
4.1 Voltage-sensing resistors in a voltage-sensing circuit
For the voltage-sensing purpose, the voltage applied across R1+R2+R3 in Figure 3.1 is detected.
Even if HV is much higher than the input voltage range of an isolation amplifier, it is possible for
TLP7820 to detect divided voltage with a divider. The voltage-sensing error is determined
considering the tolerances of R1, R2, and R3 and the error of the equivalent input resistance R
kΩ) across Pin 2 and GND of TLP7820. The followings are calculation examples of voltage-sensing
resistors.
Eexample 1:
Sensing error : below 0.5%
Equivalent input resistor of TLP7820 (R
R1:R1 // R
0.995 = 80kΩ/(R1+80kΩ)
0.995 × R1 + 0.995 × 80kΩ = 80 kΩ
When R1 is selected from E24 series, R1 = 390 Ω.
Applied voltage : 400 V
Detecting voltage : 200 mV
© 2018
Toshiba Electronic Devices & Storage Corporation
Qty
Value
Part Number
1
̶
TLP7820
1
̶
OPA237UA
1
750Ω
1
750 kΩ
1
750 kΩ
4
10 kΩ
2
1 kΩ
1
0.5 pF
100 nF
３
2
75 pF
1
10 μF
= R1:(R1×80kΩ) / (R1+80kΩ) = 1:0.995
i
Manufacturer
Description
TOSHIBA
TI
0.25 W, ±5%
800 V, 0.25 W,
±0.5%
800 V, 0.25 W,
±0.5%
0.25 W, ±0.5%
0.25 W, ±0.5%
Ceramic, 50 V, ±10%
Ceramic, 25V, ±10%
Ceramic, 100V, ±5%
Ceramic, 16V, ±10%
) : 80 kΩ
i
∴R1 ≈ 402 Ω
10 / 19
RD014-RGUIDE-01
Typical
Packaging
Dimensions in
mm (inches)
SO8L
11.05 x 5.85
SOIC
6.0 x 4.9
3.2 x 1.6
3216
(1206)
6.3 x 3.1
6331
(2512)
6.3 x 3.1
6331
(2512)
2.0 x 1.25
2012
(0805)
2.0 x 1.25
2012
(0805)
1.0 x 0.5
1005
(0402)
2.0 x 1.25
2012
(0805)
1.6 x 0.8
1608
(0603)
2.0 x 1.25
2012
(0805)
(80
i
2018-03-15
Rev. 1
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