LTC2879X

3

Rev 0

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ELECTRICAL CHARACTERISTICS The

l

denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C. VCC = 5V unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Δ|VOD(485)|,

Δ|VOD(422)|

RS485, RS422 Change in Magnitude of

Driver Differential Output Voltage

RL = 27Ω (RS485) or

RL = 50Ω (RS422) (Figure 1)

l

0.2

V

VOC(485),

VOC(422)

RS485, RS422 Driver Common-Mode

Output Voltage

RL = 27Ω (RS485) or

RL = 50Ω (RS422) (Figure 1)

l

3

V

Δ|VOC(485)|,

Δ|VOC(422)|

RS485, RS422 Change in Magnitude of

Driver Common-Mode Output Voltage

RL = 27Ω (RS485) or

RL = 50Ω (RS422) (Figure 1)

l

0.2

V

VOD(PP)

Differential Bus Output Voltage (B´–A´)

with PROFIBUS Load

PROFIBUS LOAD (Figure 2)

RCABLE = 0Ω, VCC = 4.5V to 5.5V

RCABLE = 5.5Ω, VCC = 4.5V to 5.5V

RCABLE = 11Ω, VCC = 4.75V to 5.5V

l

l

l

4

4

4

7

7

7

VP-P(DIFF)

VP-P(DIFF)

VP-P(DIFF)

VBPP-APP

Single-Ended Bus Output Amplitude

Difference (B´PP – A´PP)

All of the Conditions Above

l

0.5

V

VBPP+APP

Single-Ended Bus Output Amplitude

Sum |B´PP + A´PP|

All of the Conditions Above

l

4

V

Differential Capacitance (A to B)

(Note 3)

Powered, VCC = 5V

Unpowered, VCC = 0V

7

12

pF

pF

IOSD

Maximum Driver Short-Circuit Current

–60V ≤ (A or B) ≤ 60V (Figure 3)

l

±150

±250

mA

Receiver

IIN

Input Current (A, B)

VCC = 0V or 5V, VBUS = 12V (Figure 4)

VCC = 0V or 5V, VBUS = –7V (Figure 4)

l

l

–194

333

µA

µA

RIN

Input Resistance

VBUS = –25V or 25V (Figure 4)

l

36

112

135

kΩ

VCM

Common Mode Input Voltage

(A+B)/2 for Data Reception

l

±25

V

VTS+

Differential Input Signal Threshold

Voltage (A–B) Rising

–25V ≤ VCM ≤ 25V, Edge Rates > 100mV/µs

(Note 4) (Figure 12)

l

40

120

200

mV

VTS–

Differential Input Signal Threshold

Voltage (A–B) Falling

–25V ≤ VCM ≤ 25V, Edge Rates > 100mV/µs

(Note 4) (Figure 12)

l

–40

–120

–200

mV

ΔVTS

Differential Input Signal Hysteresis

Edge Rates > 100mV/µs (Note 4) (Figure 12)

240

mV

VTFS+

Differential Input Failsafe Threshold

Voltage (A–B) Rising

–25V ≤ VCM ≤ 25V, DC Bus Voltages

(Figure 12)

l

–10

–75

–200

mV

VTFS–

Differential Input Failsafe Threshold

Voltage (A–B) Falling

–25V ≤ VCM ≤ 25V, DC Bus Voltages

(Figure 12)

l

–40

–120

–200

mV

ΔVTFS

Differential Input Failsafe Hysteresis

DC Bus Voltages (Figure 12)

45

mV

VOH

Receiver Output High Voltage

VCC ≥ 3.0V, I(RO) = –3mA

l

VCC – 0.4V

V

VOL

Receiver Output Low Voltage

VCC ≥ 3.0V, I(RO) = 3mA

l

0.4

V

Receiver Three-State (High Impedance)

Output Current on RO

RE = High, RO = 0V

l

–20

–40

µA

Receiver Three-State (High Impedance)

Output Current on RO

RE = High, RO = VCC

l

0

5

µA

Receiver Short-Circuit Current

RE = Low, RO = 0V or VCC

l

±12

±20

mA

Logic

Low Level Input Voltage (DE, DI, RE)

3.0 ≤ VCC ≤ 5.5V

l

0.25 • VCC

V

High Level Input Voltage (DE, DI, RE)

3.0 ≤ VCC ≤ 5.5V

l

0.75 • VCC

V

Logic Input Current Low (DE)

DE = 0V

l

0

–5

µA

Logic Input Current Low (DI, RE)

DI or RE = 0V

l

–3

–10

–20

µA

Logic Input Current High (DE)

DE = VCC

l

3

10

20

µA

Logic Input Current High (DI, RE)

(DI, RE) = VCC

l

0

5

µA