CPC7594MC IXYS, CPC7594MC Datasheet - Page 16

• Manufacturer Part Number: CPC7594MC
• Manufacturer: IXYS

Specifications of CPC7594MC

• Lead Free Status / RoHS Status: Supplier Unconfirmed

CPC7594
As an input, the T
CPC7594 into the “All-Off” state by simply pulling the
input to a logic low. For applications using low-voltage
logic devices (lower than V
use of an open-collector or an open-drain type output
to control T
current to ground during normal operation when the
all-off state is not required. In general, Clare
recommends all applications use an open-collector or
open-drain type device to drive this pin.
Unlike the CPC7584, driving T
this pin to V
thermal shutdown circuitry inside the CPC7594. As a
result the T
However, the CPC7594 T
recommended operating states when it is used as an
input control. A logic 0, which forces the device to the
all-off state and a high impedance (Z) state for normal
operation. This requires the use of an open-collector
or open-drain type buffer.
2.6 Ringing Switch Zero-Cross Current Turn Off
After the application of a logic input to turn SW4 off,
the ringing switch is designed to delay the change in
state until the next zero-crossing. Once on, the switch
requires a zero-current cross to turn off, and therefore
should not be used to switch a pure DC signal. The
switch will remain in the on state no matter the logic
input until the next zero crossing. These switching
characteristics will reduce and possibly eliminate
overall system impulse noise normally associated with
ringing switches. See Clare’s application note AN-144,
Impulse Noise Benefits of Line Card Access Switches
more information. The attributes of ringing switch SW4
may make it possible to eliminate the need for a
zero-cross switching scheme. A minimum impedance
of 300 Ω in series with the ringing generator is
recommended.
2.7 Power Supplies
Both a +5 V supply and battery voltage are connected
to the CPC7594. Switch state control is powered
exclusively by the +5 V supply. As a result, the
CPC7594 exhibits extremely low power consumption
during active and idle states.
Although battery power is not used for switch control, it
is required to supply trigger current for the integrated
internal protection circuitry SCR during fault
conditions. This integrated SCR is designed to
activate whenever the voltage at T
to 4 V below the applied voltage on the V
16
SD
SD
CC
. This avoids sinking the T
pin may be held at a logic high.
will not prevent normal operation of the
SD
pin is utilized to place the
SD
DD
pin has only two
), Clare recommends the
SD
to a logic 1 or tying
BAT
or R
SD
BAT
BAT
pull up bias
pin.
drops 2
for
www.clare.com
Because the battery supply at this pin is required to
source trigger current during negative overvoltage
fault conditions at tip and ring, it is important that the
net supplying this current be a low impedance path for
high speed transients such as lightning. This will
permit trigger currents to flow enabling the SCR to
activate and thereby prevent a fault induced negative
overvoltage event at the T
2.8 Battery Voltage Monitor
The CPC7594 also uses the V
battery voltage. If system battery voltage is lost, the
CPC7594 immediately enters the all-off state. It
remains in this state until the battery voltage is
restored. The device also enters the all-off state if the
battery voltage rises more positive than about –10 V
with respect to ground and remains in the all-off state
until the battery voltage drops below approximately
–15 V with respect to ground. This battery monitor
feature draws a small current from the battery (less
than 1 µA typical) and will add slightly to the device’s
overall power dissipation.
This monitor function performs properly if the
CPC7594 and SLIC share a common battery supply
origin. Otherwise, if battery is lost to the CPC7594 but
not to the SLIC, then the V
biased by the potential applied at the T
pins via the internal protection circuitry SCR trigger
current path.
2.9 Protection
The CPC7594 uses a combination of current limited
break switches, a diode bridge/SCR clamping circuit,
and a thermal shutdown mechanism to protect the
SLIC device or other associated circuitry from damage
during line transient events such as lightning. During a
positive transient condition, the fault current is
conducted through the diode bridge to ground via
F
ground. During a negative transient of 2 to 4 V more
negative than the voltage source at V
conducts and faults are shunted to F
or the diode bridge.
GND
2.9.1 Diode Bridge/SCR
. Voltage is clamped to a diode drop above
BAT
BAT
or R
BAT
pin will be internally
BAT
voltage to monitor
GND
BAT
nodes.
BAT
, the SCR
via the SCR
or R
BAT
R01.1