ADM2582EBRWZ-REEL7(2009) 查看數據表（PDF） - Analog Devices

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ADM2582EBRWZ-REEL7
(Rev.:2009)

Signal and Power Isolated RS-485 Transceiver with ±15 kV ESD Protection

Analog Devices 

ADM2582E/ADM2587E

In the case of unipolar ac or dc voltage, the stress on the insulation

is significantly lower. This allows operation at higher working

voltages while still achieving a 50-year service life. The working

voltages listed in Table 9 can be applied while maintaining the

50-year minimum lifetime, provided the voltage conforms to either

the unipolar ac or dc voltage cases. Any crossinsulation voltage

waveform that does not conform to Figure 37 or Figure 38 should

be treated as a bipolar ac waveform, and its peak voltage should

be limited to the 50-year lifetime voltage value listed in Table 9.

RATED PEAK VOLTAGE

0V

ISOLATED POWER SUPPLY CONSIDERATIONS

The typical output voltage of the integrated isoPower dc-to-dc

isolated supply is 3.3 V. The isolated supply in the ADM2587E

is capable of supplying a current of 55 mA when the junction

temperature of the device is kept below 120°C. It is important

to note that the current available on the VISOOUT pin is the total

current available and includes the current required to supply the

internal RS-485 circuitry.

The ADM2587E can typically supply 15 mA externally on

VISOOUT when the driver is switching at 500 kbps loaded with 54 Ω,

while the junction temperature of the part is less than 120°C.

Figure 36. Bipolar AC Waveform

RATED PEAK VOLTAGE

0V

Figure 37. DC Waveform

RATED PEAK VOLTAGE

Table 14. Typical Maximum External Current Available

on VISOOUT

External Load

Current (mA)

RT

System Configuration

15

54 Ω

Double terminated bus with

RT = 110 Ω

29

120 Ω

Single terminated bus

46

Unloaded Unterminated bus

0V

NOTES

1. THE VOLTAGE IS SHOWN AS SINUSODIAL FOR ILLUSTRATION

PURPOSES ONLY. IT IS MEANT TO REPRESENT ANY VOLTAGE

WAVEFORM VARYING BETWEEN 0 AND SOME LIMITING VALUE.

THE LIMITING VALUE CAN BE POSITIVE OR NEGATIVE, BUT THE

VOLTAGE CANNOT CROSS 0V.

Figure 38. Unipolar AC Waveform

VCC

VCC

The ADM2582E typically has no current available externally

on VISOOUT.

When external current is drawn from the VISOOUT pin, there is

an increased risk of generating radiated emissions due to the

high frequency switching elements used in the isoPower dc to-

dc converter. Special care must be taken during PCB layout to

meet emissions standards. See Application Note AN-0971,

Control of Radiated Emissions with isoPower Devices, for details

on board layout considerations.

VISOOUT

EXTERNAL

LOAD

GND1

isoPower DC-TO-DC CONVERTER

OSCILLATOR

RECTIFIER

GND

GND2

REGULATOR

VISOIN

TxD

500kbps

DIGITAL ISOLATION iCoupler

ENCODE

DECODE

TRANSCEIVER

Y

D

Z

VCC

DE

ENCODE

DECODE

RT

RxD

DECODE

ENCODE

A

R

B

RE

ADM2582E/ADM2587E

GND1

ISOLATION

BARRIER

GND2

Figure 39. ADM2587E Typical Maximum External Current Measurements

Rev. 0 | Page 17 of 20

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