Toshiba TLP7820, Reference Manual

Page: 10 / 19

RD014-RGUIDE-01
2018-03-15
Rev. 1
10 / 19
© 2018
Toshiba Electronic Devices & Storage Corporation
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
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
i
(80
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
i
) : 80 kΩ
R1:R1 // R
i
= R1:(R1×80kΩ) / (R1+80kΩ) = 1:0.995
0.995 = 80kΩ/(R1+80kΩ)
0.995 × R1 + 0.995 × 80kΩ = 80 kΩ ∴R1 ≈ 402 Ω
When R1 is selected from E24 series, R1 = 390 Ω.
Applied voltage : 400 V
Detecting voltage : 200 mV
No. Ref. Qty Value Part Number Manufacturer Description Packaging
Typical
Dimensions in
mm (inches)
1 IC1 1 ̶ TLP7820 TOSHIBA SO8L 11.05 x 5.85
2 IC2 1 ̶ OPA237UA TI SOIC 6.0 x 4.9
３
R1 1 750Ω 0.25 W, ±5% 3216
3.2 x 1.6
(1206)
4 R2 1 750 kΩ
800 V, 0.25 W,
±0.5%
6331
6.3 x 3.1
(2512)
５
R3 1 750 kΩ
800 V, 0.25 W,
±0.5%
6331
6.3 x 3.1
(2512)
6 R4, R5, R6, R7 4 10 kΩ 0.25 W, ±0.5% 2012
2.0 x 1.25
(0805)
7 R8, R9 2 1 kΩ 0.25 W, ±0.5% 2012
2.0 x 1.25
(0805)
8 C1 1 0.5 pF Ceramic, 50 V, ±10% 1005
1.0 x 0.5
(0402)
9 C2, C3, C6
３
100 nF Ceramic, 25V, ±10% 2012
2.0 x 1.25
(0805)
10 C4, C5 2 75 pF Ceramic, 100V, ±5% 1608
1.6 x 0.8
(0603)
11 C7 1 10 μF Ceramic, 16V, ±10% 2012
2.0 x 1.25
(0805)