SP3070-3078E Datasheet, PDF (15/19 Pages) Sipex Corporation – 15kV ESD-Protected, 3.3V, 1/8 Load, Failsafe RS-485/RS422 Transceivers

eration, shutdown, and powered down. After
an ESD event, the SP3070E - SP3078E keep
working without latchup or damage.
ESD protection can be tested in various ways.
The transmitter outputs and receiver inputs of
the SP3070E - SP3078E are characterized
for protection to the following limits:
■ ±15kV using the Human Body Model
■ ±8kV using the Contact Discharge
method specified in IEC 1000-4-2
■ ±15kV Airgap
ESD TEST CONDITIONS
ESD performance depends on a variety of
conditions. Contact Sipex for a reliability
report that documents test setup, method-
ology and results.
IEC 1000-4-2
The IEC 1000-4-2 standard covers ESD
testing and performance of finished equip-
ment. However, it does not specifically refer
to integrated circuits. The SP3070E family
of devices helps you design equipment to
meet IEC 1000-4-2, without the need for
additional ESD-protection components.
The major difference between tests done
using the Human Body Model and IEC 1000-
4-2 is higher peak current in IEC 1000-4-2,
because series resistance is lower in the
IEC 1000-4-2 model. Hence, the ESD with-
stand voltage measured to EC 1000-4-2 is
generally lower than that measured using
the human body model.
The air-gap test involves approaching the
device with a charged probe. The contact-
discharge method connects the probe to the
device before the probe is energized.
MACHINE MODEL
The machine model for ESD tests all pins
using a 200pF storage capacitor and zero
discharge resistance. The objective is to
emulate the stress caused when I/O pins are
contacted by handling equipment during test
and assembly.
DETAILED DESCRIPTION
256 TRANSCEIVERS ON THE BUS
The standard RS-485 receiver input imped-
ance is 12kΩ (1 unit load), and the standard
driver can drive up to 32 unit loads. The
SP3070E family of transceivers has a 1/8-
unit load receiver input impedance (96Ω),
allowing up to 256 transceivers to be con-
nected in parallel on one communication
line. Any combination of these devices as
well as other RS-485 transceivers with a
total of 32 unit loads or fewer can be con-
nected to the line.
REDUCED EMI AND REFLECTIONS
The SP3070E, SP3071E and SP3072E fea-
ture reduced slew-rate drivers that minimize
EMI and reduce reflections caused by im-
properly terminated cables, allowing error-
free data transmission up to 250kbps. The
SP3073, SP3074 and SP3075 offer higher
driver output slew-rate limits, allowing trans-
mit speeds up to 500kbps.
LOW POWER SHUTDOWN MODE
Low-power shutdown mode is initiated by
bringing both RE high and DE low. In shut-
down, the devices typically draw only 50nA
of supply current.
RE and DE can be driven simultaneously;
the parts are guaranteed not to enter shut-
down 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.
Enable times t_ZH and t_ZL assume the part
was not in a low-power shutdown state.
Enable times t_ZH(SHDN) and t_ZL(SHDN) assume
the parts were shut down. It takes drivers
and receivers longer to become enabled
from low-power shutdown mode t_ZH(SHDN)
and t_ZL(SHDN) than from driver/receiver-dis-
able mode (t_ZH, t_ZL)
Date: 03/28/05
SP3070E - SP3078E Family, ±15kV ESD-Protected, Failsafe RS-485/RS422 Transceivers
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© Copyright 2005 Sipex Corporation