Datasheet > ACNT-H79B

ACNT-H79B

更新时间： 2022-02-26 12:18:35

品牌	Logo	应用领域
博通 - BOARDCOM		/
页数	文件大小	规格书
16页	979K
描述
Optical Isolation Amplifier in 15 mm Stretched SO-8 Package

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ACNT-H79B 数据手册

ACNT-H79B, ACNT-H79A, ACNT-H790

Data Sheet

Application Information

Figure 23 Motor Output Horsepower vs. Motor Phase Current and

Supply Voltage

Shunt Resistor Connections

The typical method for connecting the ACNT-H79B/H79A/H790

to the current sensing resistor is shown in Figure 21. V (pin 2)

IN+

440 V

is connected to the positive terminal of the sense resistor, while

380 V

(pin ±) is shorted to GND1 (pin 4), with the power-supply

220 V

IN–

120 V

return path functioning as the sense line to the negative

terminal of the current sense resistor.

This allows a single pair of wires or PC board traces to connect

the isolation amplifier circuit to the sense resistor. By

referencing the input circuit to the negative side of the sense

resistor, any load current induced noise transients on the

resistor are seen as a common-mode signal and will not

interfere with the current-sense signal. This is important

because the large load currents flowing through the motor

drive, along with the parasitic inductances inherent in the

wiring of the circuit, can generate both noise spikes and offsets

that are relatively large compared to the small voltages that are

being measured across the current sensing resistor.

MOTOR PHASE CURRENT - A (rms)

Output Side

The op-amp used in the external post-amplifier circuit should

be of sufficiently high precision so that it does not contribute a

significant amount of offset or offset drift relative to the

contribution from the isolation amplifier. Generally, op-amps

with bipolar input stages exhibit better offset performance

than op-amps with JFET or MOSFET input stages.

If the same power supply is used both for the gate drive circuit

and for the current sensing circuit, it is very important that the

connection from GND1 of the ACNT-H79B/H79A/H790 to the

sense resistor be the only return path for supply current to the

gate drive power supply in order to eliminate potential ground

loop problems. The only direct connection between the

ACNT-H79B/H79A/H790 circuit and the gate drive circuit

should be the positive power supply line.

In addition, the op-amp should also have enough bandwidth

and slew rate so that it does not adversely affect the response

speed of the overall circuit. The post-amplifier circuit includes a

pair of capacitors (C5 and C6) that form a single-pole low-pass

filter; these capacitors allow the bandwidth of the post-amp to

be adjusted independently of the gain and are useful for

reducing the output noise from the isolation amplifier.

Differential Input Connection

The differential analog inputs of the ACNT-H79B/H79A/H790

are implemented with a fully-differential, switched-capacitor

circuit. In the typical application circuit (Figure 21), the isolation

amplifier is connected in a single-ended input mode. Given the

fully differential input structure, a differential input connection

method (balanced input mode as shown in Figure 24) is

recommended to achieve better performance. The input

currents created by the switching actions on both of the pins

are balanced on the filter resistors and cancelled out each

other. Any noise induced on one pin will be coupled to the

other pin by the capacitor C and creates only common mode

noise that is rejected by the device. Typical value for Ra and Rb

is 10  and 22 nF for C.

The gain-setting resistors in the post-amp should have a

tolerance of 1% or better to ensure adequate CMRR and

adequate gain tolerance for the overall circuit. Resistor

networks can be used that have much better ratio tolerances

than can be achieved using discrete resistors. A resistor

network also reduces the total number of components for the

circuit as well as the required board space.

Broadcom

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与ACNT-H79B相关器件

型号	品牌	获取价格	描述	数据表
ACNT-H870	BOARDCOM	获取价格	Precision Optically Isolated Voltage Sensor in a 15-mm Stretched SO-8 Package
ACNT-H87A	BOARDCOM	获取价格	Precision Optically Isolated Voltage Sensor in a 15-mm Stretched SO-8 Package
ACNT-H87B	BOARDCOM	获取价格	Precision Optically Isolated Voltage Sensor in a 15-mm Stretched SO-8 Package
ACNV2601	AVAGO	获取价格	High Insulation Voltage 10 MBd Digital Optocoupler
ACNV2601-000E	AVAGO	获取价格	1 CHANNEL LOGIC OUTPUT OPTOCOUPLER, 10Mbps, 0.500 INCH, ROHS COMPLIANT, PLASTIC, WIDE BODY
ACNV2601-300E	AVAGO	获取价格	High Insulation Voltage 10 MBd Digital Optocoupler
ACNV2601-500E	AVAGO	获取价格	1 CHANNEL LOGIC OUTPUT OPTOCOUPLER, 10Mbps, 0.500 INCH, ROHS COMPLIANT, PLASTIC, WIDE BODY
ACNV260E	AVAGO	获取价格	2mm DTI, 10MBd Digital Optocoupler 13mm creepage and clearance
ACNV260E-300E	AVAGO	获取价格	1 CHANNEL LOGIC OUTPUT OPTOCOUPLER, 10Mbps, 0.500 INCH, ROHS COMPLIANT, SURFACE MOUNT, DIP
ACNV260E-500E	AVAGO	获取价格	1 CHANNEL LOGIC OUTPUT OPTOCOUPLER, 10Mbps, 0.500 INCH, ROHS COMPLIANT, SURFACE MOUNT, DIP

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