RD014-RGUIDE-01
2018-03-15
Rev. 1
3
/
19
© 2018
Toshiba Electronic Devices & Storage Corporation
1. Overview
Factory Automation (FA) market has AC servo, General Purpose Inverter, Solar Power Generation
and Wind Power Generation areas and those applicationʼs key design point is to accurate current
sense, voltage sense so that each application can realize high accuracy and stability of motions and
controls and isolation performance between input and output signals. In order to realize such kind
of high accuracy motions and controls, system has to monitor motorʼs current and voltage and
feedback them to microcontroller (MCU) more properly.
The TLP7820 is an isolation amplifier which has optical coupled isolation feature in order to meet
above requirement with 0.02% (typical) linearity accuracy. The TLP7820 also provides a common-
mode transient immunity (CMTI) of 20 kV/μs (typical), therefore stable even in noisy motor control
environments. In addition, the guaranteed isolation voltage of 5000 Vrms (minimum) makes the
TLP7820 suit various industrial applications.
In order to achieve those characteristics, the TLP7820 has a high-precision delta-sigma AD
converter at the primary side and DA converter at the secondary side. The primary and secondary
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 secondary side, the optical signal
is received by a photodiode, decoded by a decoder circuit, converted back to an analog signal by a
DA converter, filtered internal conversion noise by a lowpass filter (LPF), then output analog signal
properly.
This reference guide provides the unique features and characteristics of the TLP7820, focusing on
common-mode transient immunity, nonlinearity characteristic, and power consumption, as well as
design guidelines for typical voltage-sensing applications. For details of other features and functions
of the TLP7820, see its datasheet.
To download the datasheet for the TLP7820 →
1.1 Target applications
Voltage sensing for industrial motor applications, including inverters, servo amplifiers, robots,
machine tools, and high-capacity power supplies
Voltage sensing for wind power and PV inverters, and industrial storage battery systems
Voltage sensing for office and housing equipment, including uninterruptible power supplies
(UPS), server power supplies, home storage battery systems, and air conditioners
