CPC7592BC Datasheet CPC7592BA, CPC7592BCTR, CPC7592BB | P16-P18

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CPC7592

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 IXYS IC Division’s application

note AN-144, Impulse Noise Benefits of Line Card Access

Switches for 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 in series with the ringing

generator is recommended.

2.7 Power Supplies

Both a +5 V supply and battery voltage are connected

to the CPC7592. Switch state control is powered

exclusively by the +5 V supply. As a result, the

CPC7592 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

BAT

or R

BAT

drops 2

to 4 V below the applied voltage on the V

BAT

pin.

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

BAT

or R

BAT

nodes.

2.8 Battery Voltage Monitor

The CPC7592 also uses the V

BAT

voltage to monitor

battery voltage. If system battery voltage is lost, the

CPC7592 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 A typical) and will add slightly to the device’s

overall power dissipation.

This monitor function performs properly if the

CPC7592 and SLIC share a common battery supply

origin. Otherwise, if battery is lost to the CPC7592 but

not to the SLIC, then the V

BAT

pin will be internally

biased by the potential applied at the T

BAT

or R

BAT

pins via the internal protection circuitry SCR trigger

current path.

2.9 Protection

2.9.1 Diode Bridge/SCR

The CPC7592 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

GND

. Voltage is clamped to a diode drop above

ground. During a negative transient of 2 to 4 V more

negative than the voltage source at V

BAT

, the SCR

conducts and faults are shunted to F

GND

via the SCR

or the diode bridge.

In order for the SCR to crowbar (or foldback), the

SCR’s on-voltage (see “Protection Circuitry Electrical

Specifications” on page 9) must be less than the applied

voltage at the V

BAT

pin. If the V

BAT

voltage is less

negative than the SCR on-voltage or if the V

BAT

supply

is unable to source the trigger current, the SCR will not

crowbar.

For power induction or power-cross fault conditions,

the positive cycle of the transient is clamped to a diode

drop above ground and the fault current directed to

ground. The negative cycle of the transient will cause

the SCR to conduct when the voltage exceeds the

BAT

reference voltage by two to four volts, steering

the fault current to ground.

Note: The CPC7592xB does not contain the

protection SCR but instead uses diodes to clamp both

polarities of a transient fault. These diodes direct the

negative potential’s fault current to the V

BAT

pin.

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2.9.2 Current Limiting function

If a lightning strike transient occurs when the device is

in the talk state, the current is passed along the line to

the integrated protection circuitry and restricted by the

dynamic current limit response of the active switches.

During the talk state, when a 1000V 10x1000 s

lightning pulse (GR-1089-CORE) is applied to the line

though a properly clamped external protector, the

current seen at T

LINE

and R

LINE

will be a pulse with a

typical magnitude of 2.5 A and a duration less than

0.5 s.

If a power-cross fault occurs with the device in the talk

state, the current is passed though break switches

SW1 and SW2 on to the integrated protection circuit

but is limited by the dynamic DC current limit response

of the two break switches. The DC current limit

specified over temperature is between 80 mA and

425 mA and the circuitry has a negative temperature

coefficient. As a result, if the device is subjected to

extended heating due to a power cross fault condition,

the measured current at T

LINE

and R

LINE

will decrease

as the device temperature increases. If the device

temperature rises sufficiently, the temperature

shutdown mechanism will activate and the device will

enter the all-off state.

2.10 Thermal Shutdown

The thermal shutdown mechanism activates when the

device die temperature reaches a minimum of 110 C,

placing the device in the all-off state regardless of

logic input. During thermal shutdown events the T

pin will output a logic low with a nominal 0 V level. A

logic high is output from the T

pin during normal

operation with a typical output level equal to V

If presented with a short duration transient such as a

lightning event, the thermal shutdown feature will

typically not activate. But in an extended power-cross

event, the device temperature will rise and the thermal

shutdown mechanism will activate forcing the switches

to the all-off state. At this point the current measured

into T

LINE

or R

LINE

will drop to zero. Once the device

enters thermal shutdown it will remain in the all-off

state until the temperature of the device drops below

the de-activation level of the thermal shutdown circuit.

This permits the device to autonomously return to

normal operation. If the transient has not passed,

current will again flow up to the value allowed by the

dynamic DC current limiting of the switches and

heating will resume, reactivating the thermal shutdown

mechanism. This cycle of entering and exiting the

thermal shutdown mode will continue as long as the

fault condition persists. If the magnitude of the fault

condition is great enough, the external secondary

protector will activate shunting the fault current to

ground.

2.11 External Protection Elements

The CPC7592 requires only over voltage secondary

protection on the loop side of the device. The

integrated protection feature described above negates

the need for additional external protection on the SLIC

side. The secondary protector must limit voltage

transients to levels that do not exceed the breakdown

voltage or input-output isolation barrier of the

CPC7592. A foldback or crowbar type protector is

recommended to minimize stresses on the CPC7592.

Consult IXYS IC Division’s application note, AN-100,

“Designing Surge and Power Fault Protection Circuits for

Solid State Subscriber Line Interfaces” for equations

related to the specifications of external secondary

protectors, fused resistors and PTCs.

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CPC7592

3 Manufacturing Information

3.1 Moisture Sensitivity

All plastic encapsulated semiconductor packages are susceptible to moisture ingression. IXYS Integrated

Circuits Division classified all of its plastic encapsulated devices for moisture sensitivity according to the

latest version of the joint industry standard, IPC/JEDEC J-STD-020, in force at the time of product

evaluation. We test all of our products to the maximum conditions set forth in the standard, and guarantee

proper operation of our devices when handled according to the limitations and information in that standard as well as

to any limitations set forth in the information or standards referenced below.

Failure to adhere to the warnings or limitations as established by the listed specifications could result in reduced

product performance, reduction of operable life, and/or reduction of overall reliability.

This product carries a Moisture Sensitivity Level (MSL) rating as shown below, and should be handled according to

the requirements of the latest version of the joint industry standard IPC/JEDEC J-STD-033.

3.2 ESD Sensitivity

This product is ESD Sensitive, and should be handled according to the industry standard

JESD-625.

3.3 Reflow Profile

This product has a maximum body temperature and time rating as shown below. All other guidelines of

J-STD-020 must be observed.

3.4 Board Wash

IXYS Integrated Circuits Division recommends the use of no-clean flux formulations. However, board washing to

remove flux residue is acceptable, and the use of a short drying bake may be necessary. Chlorine-based or

Fluorine-based solvents or fluxes should not be used. Cleaning methods that employ ultrasonic energy should not be

used.

Device Moisture Sensitivity Level (MSL) Rating

CPC7592BA / CPC7592BB / CPC7592BC MSL 1

Device Maximum Temperature x Time

CPC7592BA / CPC7592BB / CPC7592BC 260°C for 30 seconds

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P19

CPC7592BC

Mfr. #:

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Manufacturer:

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Switch ICs - Various 6-pole SOIC LCAS extra logic

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