MAX487CUA+T Maxim Integrated Products, MAX487CUA+T Datasheet - Page 11

• Manufacturer Part Number: MAX487CUA+T
• Description: IC TXRX RS485/RS422 8-UMAX
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX487CUA+T

• Number Of Drivers/receivers: 1/1
• Protocol: RS422, RS485
• Voltage - Supply: 4.75 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A low-power shutdown mode is initiated by bringing
both RE high and DE low. The devices will not shut
down unless both the driver and receiver are disabled.
In shutdown, the devices typically draw only 0.1µA of
supply current.
RE and DE may be driven simultaneously; the parts are
guaranteed not to enter shutdown if RE is high and DE
is low for less than 50ns. If the inputs are in this state
for at least 600ns, the parts are guaranteed to enter
shutdown.
For the MAX481, MAX483, and MAX487, the t
t
power shutdown state (the MAX485/MAX488–MAX491
and MAX1487 can not be shut down). The t
and t
down (see Electrical Characteristics ).
It takes the drivers and receivers longer to become
enabled from the low-power shutdown state
(t
(t
DE inputs equal a logical 0,1 or 1,1 or 0, 0.)
Figure 12. Driver Output Waveform and FFT Plot of MAX481/
MAX485/MAX490/MAX491/MAX1487 Transmitting a 150kHz
Signal
ZL
ZH
ZH(SHDN
10dB/div
enable times assume the part was not in the low-
, t
ZL(SHDN)
ZL
). (The parts are in operating mode if the
0Hz
), t
ZL(SHDN)
enable times assume the parts were shut
______________________________________________________________________________________
Low-Power Shutdown Mode
(MAX481/MAX483/MAX487)
) than from the operating mode
500kHz/div
Low-Power, Slew-Rate-Limited
5MHz
ZH(SHDN)
RS-485/RS-422 Transceivers
ZH
and
–
R
—
E
–
,
Excessive output current and power dissipation caused
by faults or by bus contention are prevented by two
mechanisms. A foldback current limit on the output
stage provides immediate protection against short cir-
cuits over the whole common-mode voltage range (see
Typical Operating Characteristics ). In addition, a ther-
mal shutdown circuit forces the driver outputs into a
high-impedance state if the die temperature rises
excessively.
Many digital encoding schemes depend on the differ-
ence between the driver and receiver propagation
delay times. Typical propagation delays are shown in
Figures 15–18 using Figure 14’s test circuit.
The difference in receiver delay times, | t
typically under 13ns for the MAX481, MAX485,
MAX490, MAX491, and MAX1487 and is typically less
than 100ns for the MAX483 and MAX487–MAX489.
The driver skew times are typically 5ns (10ns max) for
the MAX481, MAX485, MAX490, MAX491, and
MAX1487, and are typically 100ns (800ns max) for the
MAX483 and MAX487–MAX489.
Figure 13. Driver Output Waveform and FFT Plot of MAX483/
MAX487–MAX489 Transmitting a 150kHz Signal
10dB/div
0Hz
Driver Output Protection
500kHz/div
Propagation Delay
PLH
5MHz
- t
PHL
|, is
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