LTC1387 View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LTC1387 Datasheet PDF : 12 Pages
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LTC1387
AC ELECTRICAL CHARACTERISTICS
TA = 25°C, VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF (Notes 2, 3), unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
RS485 Mode (Fast Slew Rate, ON = DXEN = High, 485/232 = High, SLEW = High)
tZL
Driver Enable to Output Low
Figures 3, 8, CL = 100pF, S1 Closed
tZH
Driver Enable to Output High
Figures 3, 8, CL = 100pF, S2 Closed
tLZ
Driver Disable from Low
Figures 3, 8, CL = 15pF, S1 Closed
tHZ
Driver Disable from High
Figures 3, 8, CL = 15pF, S2 Closed
RS485 Mode (Slow Slew Rate, ON = DXEN = High, 485/232 = High, SLEW = Low)
t PLH
Driver Input to Output
t PHL
Driver Input to Output
tSKEW
Driver Output to Output
tr, tf
Driver Rise or Fall Time
tZL
Driver Enable to Output Low
tZH
Driver Enable to Output High
tLZ
Driver Disable from Low
tHZ
Driver Disable from High
RS485 Mode (ON = RXEN = High, 485/232 = High)
Figures 2, 7, RL = 54Ω, CL = 100pF
Figures 2, 7, RL = 54Ω, CL = 100pF
Figures 2, 7, RL = 54Ω, CL = 100pF
Figures 2, 7, RL = 54Ω, CL = 100pF
Figures 3, 8, CL = 100pF, S1 Closed
Figures 3, 8, CL = 100pF, S2 Closed
Figures 3, 8, CL = 15pF, S1 Closed
Figures 3, 8, CL = 15pF, S2 Closed
MIN TYP MAX UNITS
q
50
90
ns
q
50
90
ns
q
50
90
ns
q
60
90
ns
q 100
700 1500
ns
q 100
700 1500
ns
q
200 750
ns
q 150
300 1500
ns
q
600 1500
ns
q
600 1500
ns
q
100 200
ns
q
100 200
ns
t PLH
Receiver Input to Output
t PHL
Receiver Input to Output
tSKEW
Differential Receiver Skew, tPLH – tPHL
Receiver Output Enable/Disable (ON = High)
tZL
Receiver Enable to Output Low
tZH
Receiver Enable to Output High
tLZ
Receiver Disable from Low
tHZ
Receiver Disable from High
Figures 2, 9, RL = 54Ω, CL = 100pF
Figures 2, 9, RL = 54Ω, CL = 100pF
Figures 2, 9, RL = 54Ω, CL = 100pF
Figures 6, 12, CL = 15pF, S1 Closed
Figures 6, 12, CL = 15pF, S2 Closed
Figures 6, 12, CL = 15pF, S1 Closed
Figures 6, 12, CL = 15pF, S2 Closed
q 20
70
140
ns
q 20
70
140
ns
10
ns
q
40
90
ns
q
40
90
ns
q
40
90
ns
q
40
90
ns
The q denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 3: All typicals are given at VCC = 5V, C1 = C2 = C3 = C4 = 0.1µF
and TA = 25°C.
Note 4: Short-circuit current for RS485 driver output low state folds back
above VCC. Peak current occurs around VO = 3V.
Note 5: SLEW includes an internal pull-up in RS485 mode.
PIN FUNCTIONS
C1+ (Pin 1): Commutating Capacitor C1 Positive Terminal.
Requires an external 0.1µF capacitor between Pins 1 and 2.
C1– (Pin 2): Commutating Capacitor C1 Negative Terminal.
VDD (Pin 3): Charge Pump Positive Supply Output.
Requires an external 0.1µF capacitor to ground.
A (Pin 4): Receiver Input A. Inverting input of RS232
receiver A in RS232 mode; inverting RS485 receiver input
in RS485 mode.
B (Pin 5): Receiver Input B. Inverting input of RS232
receiver B in RS232 mode; noninverting RS485 receiver
input in RS485 mode.
Y (Pin 6): Driver Output Y. Inverting RS232 driver Y output
in RS232 mode; inverting RS485 driver output in RS485
mode.
Z (Pin 7): Driver Output Z. Inverting RS232 driver Z output
in RS232 mode; noninverting RS485 driver output in
RS485 mode.
4
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