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RD014-RGUIDE-01

2018-03-15

Rev. 1

Toshiba Electronic Devices & Storage Corporation

6.4 Output voltages for different primary- and secondary-side power supply

combinations

Table 6.1 shows the output voltages obtained from different primary- and secondary-side power

supply combinations.

Table 6.1 Output voltages for different power supply combinations

∎ V

OUT+

output ∎ V

OUT-

output

Primary-Side Power

Supply, V

DD1

Primary-Side Power

Supply, V

DD1

OFF

Secondary-

Side Power

Supply

DD2

x Gain/2

+1.25 (V)

GND

Secondary-

Side Power

Supply

DD2

x Gain/2

+1.25 (V)

+2.5 V

OFF

GND

OFF

GND

Содержание TLP7820

Страница 1: ...RD014 RGUIDE 01 2018 03 15 Rev 1 1 19 2018 Toshiba Electronic Devices Storage Corporation Isolation Amplifier Application Circuits Voltage Sensing of the TLP7820 Reference Guide RD014 RGUIDE 01 ...

Страница 2: ...sing 9 3 2 Bill of materials 10 4 GUIDELINES FOR DESIGNING A VOLTAGE SENSING CIRCUIT 10 4 1 Voltage sensing resistors in a voltage sensing circuit 10 4 2 Test mode considerations 11 5 SIMULATION 11 5 1 Basic operation 11 5 2 Noise superimposed on the input voltage 13 5 3 Circuit with filters 14 6 PRODUCT OVERVIEW 16 6 1 Overview 16 6 2 External view and pin assignment 17 6 3 Internal block diagram...

Страница 3: ... sides of the TLP7820 isolation amplifier are optically coupled using an LED and a photodiode to provide electrical isolation and internal signal transfer of optical transfer with digital signal realizes high accuracy signal transfer The delta sigma AD converter at the primary side encodes an input analog signal into digital data then optically transmitted to the secondary side by an LED At the se...

Страница 4: ...noise from outside A common mode noise generates a displacement current to flow through the internal coupling capacitance between the primary input and secondary output sides of a photocoupler and if a displacement current excees a given level into coupling capacitor the photocoupler has malfunction then resulting in faulty system operation A displacement current generated by transient common mode...

Страница 5: ...GBTs have rise and fall times tr and tf of roughly 100ns when switching Under these conditions the slew rate dV dt of VCM is calculated to be 4kV μs at a supply voltage of 400V and 8kV μs at 800V Figure 2 2 shows examples of output waveforms of the TLP7820 when common mode voltages VCM with 4 kV μs and 8 kV μs slew rates are applied As shown in Figure 2 2 VOUT does not have much noise which proves...

Страница 6: ...eristics to control system properly The output of an isolation amplifier with bad linearity characteristics does not respond accurately with specific input so there are lacking of the stability and accuracy of a system In the trend of increasing speed accurate control is required for inverters and it is important for isolation amplifier to minimize the output errors Although an electronic circuit ...

Страница 7: ... The sum of the absolute values of the maximum and minimum deviations dev_max dev_min is calculated 4 The ratio of this sum to the full scale differential output voltage VOH VOL is calculated Figure 2 5 shows the relationship between the input voltage and the output voltage deviation from the line of the best fit Figure 2 5 Input voltage vs output voltage deviation from the line of best fit NL200 ...

Страница 8: ...commend operating range 0 2 to 0 2 V This contributes reduction of the maximum circuit current simplifying the design of a primary side power supply A Competitor A B TLP7820 Figure 2 6 Relationships between the input voltage and the primary side supply current of isolation amplifiers Figure 2 7 B shows the changes in the primary side supply current in response to input voltage changes at a given f...

Страница 9: ... reduce the circuit size Obviously the constant supply current of the TLP7820 contributes power supply consumption reduction and the circuit size reduction In the trend of increasing system speed this also contributes suppress electromagnetic interference EMI caused by large supply voltage fluctuations 3 Application circuit example and its bill of materials 3 1 Example of an application circuit fo...

Страница 10: ...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 Ri 80 kΩ R1 R1 Ri 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 D...

Страница 11: ... 750Ω 750Ω 200mV R2 R3 200mV 750Ω 400V 750Ω R2 R3 1 5 MΩ When R2 and R3 are selected from E24 series R2 750 Ω and R3 750 Ω R2 and R3 are connected in series to ensure creepage distance of resistors The tolerances of R1 R2 and R3 should be considered to calculate actual voltage sensing error 4 2 Test mode considerations The TLP7820 enters test mode when either the VIN or VIN pin exceeds VDD1 2 volt...

Страница 12: ...has x8 2 as large an amplitude as the input signal 10kHz sine wave with 0 2Vp p This is equal to the specified typical gain of x8 2 of the TLP7820 indicating that simulation ran properly Figure 5 2 Simulation results Vin Vout Time 0s 50us 100us 150us 200us 250us 300us 1 V Vin 2 V Vout 250mV 200mV 150mV 100mV 50mV 0mV 50mV 100mV 150mV 200mV 250mV V i n 0 6V 0 8V 1 0V 1 2V 1 4V 1 6V 1 8V 2 0V 2 2V 2...

Страница 13: ... 5 3 shows the circuit simulated Figure 5 3 Simulation circuit superimposing a noise Figure 5 4 shows the simulation results which indicate that the output waveform was not measured properly due to the influence of the noise Figure 5 4 Simulation waveforms with noise Vin Vout V_noise is superimposed on Vin1 Time 0s 50us 100us 150us 200us 250us 300us 1 V Vin 2 V Vout 250mV 200mV 150mV 100mV 50mV 0m...

Страница 14: ...put line Noise filter frequency 230kHz Amplitude adjustment gain 0 dB Input series resistors 10 kΩ Input bypass capacitors C4 C5 68 pF Figure 5 5 shows the simulation circuit Figure 5 5 Circuit with filters simulated Figure 5 6 provides the simulation results which show that the filters removed a noise from the output waveform The output is a 10kHz sine wave with 1 64Vp p which has x8 2 as large a...

Страница 15: ...ation Figure 5 6 Results of simulation of a circuit with filters Time 0s 50us 100us 150us 200us 250us 300us 1 V Vin 2 V Vout 250mV 200mV 150mV 100mV 50mV 0mV 50mV 100mV 150mV 200mV 250mV V i n 0 6V 0 8V 1 0V 1 2V 1 4V 1 6V 1 8V 2 0V 2 2V 2 4V 2 6V V o u t 1 64 Vp p Vout Vin Vin1 V_noise ...

Страница 16: ...sumption Primary supply current 8 6 mA typical Secondary supply current 6 2 mA typical Thin package SO8L contributes flexible PCB designs Excellent output nonlinearity characteristics NL200 0 02 typical at Vin 200mV to 200mV NL100 0 015 typical at Vin 100mV to 100mV Excellent temperature stability Input offset drift 2μV C typical Gain drift 0 00012V V C typical VOUT nonlinearity drift 0 00007 C ty...

Страница 17: ... diagram Note Add 0 1μF bypass capacitors between Pin 1 and Pin 4 and between Pin 5 and Pin 8 Figure 6 2 Internal block diagram of the TLP7820 External view and marking Pin assignment Pin No Symbol Description 1 VDD1 Input side supply voltage 2 VIN Positive input 3 VIN Negative input 4 GND1 Input side ground 5 GND2 Output side ground 6 VOUT Negative output 7 VOUT Positive output 8 VDD2 Output side...

Страница 18: ...tput voltages obtained from different primary and secondary side power supply combinations Table 6 1 Output voltages for different power supply combinations VOUT output VOUT output Primary Side Power Supply VDD1 Primary Side Power Supply VDD1 ON OFF ON OFF Secondary Side Power Supply VDD2 ON VIN x Gain 2 1 25 V GND Secondary Side Power Supply VDD2 ON VIN x Gain 2 1 25 V 2 5 V OFF GND GND OFF GND G...

Страница 19: ...s which minimize risk and avoid situations in which a malfunction or failure of semiconductor devices could cause loss of human life bodily injury or damage to property including data loss or corruption Customers must also refer to and comply with the latest versions of all relevant our information including without limitation specifications data sheets and application notes for semiconductor devi...

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