SP485EN-L Datasheet, PDF (6/11 Pages) Exar Corporation – Low Power Half-Duplex RS-485 Transceivers

A
V_OD
B
R
R ^VOC
Figure 1. Driver DC Test Load Circuit
PIN FUNCTION
Pin 1 - RO - Receiver Output
Pin 2 - RE - Receiver Output Enable Active LOW
Pin 3 - DE - Driver Output Enable Active HIGH
Pin 4 - DI - Driver Input
Pin 5 - GND - Ground Connection
Pin 6 - A - Driver Output / Receiver input
Non-Inverting
Pin 7 - B - Driver Output / Receiver Input Inverting
Pin 8 - Vcc - Positive Supply 4.75V ≤ Vcc ≤ 5.25V
Test Circuits
Receiver
Output
Test Point
1kΩ
S₁
V_CC
C_RL
1kΩ
S₂
Figure 2. Receiver Timing Test Load Circuit
C_L1
DI
A
R_L
B
C_L2
A
RO
B
15pF
Figure 3. RS-485 Driver/Receiver Timing Test
Output
500Ω
Under
Test _CL
S₁
V_CC
S₂
Figure 4. Driver Timing Test Load #2 Circuit
fSP485 = 1MHz; fSP483 = 100kHz; t_R ≤10ns; t_F ≤10ns
+3V
DRIVER INPUT
0V
B
DRIVER
OUTPUT _A
DIFFERENTIAL ^VO⁺
OUTPUT 0V
V_A –V_B ^VO^–
1.5V
V_O ^1/2VO
t _SKEW = |t _DPLH - t_DPHL|
Figure 5. Driver Propagation Delays
t _PLH
t _DPLH
t_R
t _PHL
t _DPHL
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com

1.5V
1/2V_O
t_F
SP483_485_100_071410