a7860光电耦合器可用a7840代换吗

虽然脚位有相似的，但应用还是有区别的，最好不要直接代换。如实在没办法买到7840那就改一下参数试试吧！

A7860:

12-bit Linearity

200 ns Conversion Time

(Pre-Trigger Mode 2 with HCPL-0872)

12-bit Effective Resolution with 5 s Signal Delay

(14-bit with 102 s) (with HCPL-0872)

Fast 3 s Over-Range Detection (with HCPL-0872)

± 200 mV Input Range with Single 5 V Supply

1% Internal Reference Voltage Matching

Offset Calibration (with HCPL-0872)

-40°C to +85°C Operating Temperature Range

15 kV/s Isolation Transient Immunity

Safety Approval: UL 1577, CSA and IEC/EN/DIN EN

60747-5-2

The HCPL-7860/HCPL-786J Optically Isolated Modulator

and HCPL-0872 Digital Interface IC or digital filter together

form an isolated programmable two-chip analog-to-digital

converter. The isolated modulator allows direct measurement

of motor phase currents in power inverters.

Symbol Description Symbol Description

1: VDD1 Supply voltage input (4.5 V to 5.5 V)

2: VIN+ Positive input (± 200 mV recommended)

3: VIN- Negative input (normally connected to GND1)

4: GND1 Input ground

5: GND2 Output ground

6: MDAT Serial data output

7: MCLK Clock output (10 MHz typical)

8: VDD2 Supply voltage input (4.5 V to 5.5 V)

A8740:

The HCPL-7860/HCPL-786J Optically Isolated Modulator

and HCPL-0872 Digital Interface IC or digital filter together

form an isolated programmable two-chip analog-to-digital

converter. The isolated modulator allows direct measurement

of motor phase currents in power inverters.

1: VDD1 Supply voltage input (4.5 V to 5.5 V)

2: VIN+ Positive input (± 200 mV recommended)

3: VIN- Negative input (normally connected to GND1)

4: GND1 Input ground

5: GND2 Output ground

6: V0UT+

7: VOUT-

8: VDD2 Supply voltage input (4.5 V to 5.5 V)

Supply Voltages VDD1, VDD2 0.0 5.5 V

Steady-State Input Voltage VIN+, VIN- -2.0 VDD1 +0.5 V

2 Second Transient Input Voltage -6.0

Output Voltages VOUT+, VOUT- -0.5

VDD2 +0.5 V

采用霍尔电流传感器（LEM模块）采样电流，线性度好、功耗小，温度稳定性好，精度普遍较高，是较为理想的电流传感器，但是成本较高；HCPL-7860的隔离型A/D转换器能直接将模拟量转化为数字量输出，从而避免了某些场合下所需要附加的A/D转换器，可靠性高，抗干扰能力强；而采用HCPL-7840采样电流，同样具有较高的精度，且抗共模抑制比的能力较强，跟LEM模块比较，它更适合于电机电流的检测；后两种方案成本较低，具有很高的性价比，但是，这两种方案都需要精确度高、温漂小的四端采样电阻为条件，才能实现精确测量的目的，普通的两端采样电阻会极大影响采样的准确性，而且采样电阻的取值要考虑最小的功率损耗和最大的准确性的折中点，较难掌握。所以，伺服电机控制系统中电流采集方案的选择。

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