STLC5412FN datasheet(36/74 Pages) STMICROELECTRONICS

36 / 74 page

GCI: when GCI ”NT master of the clocks”configura-

tion is selected, UID provides the GCI clocks

needed for control channel transfer; PUP control in-

struction is provided to the UID by pulling low the

Bx data input; STLC5412 then reacts sending GCI

clocks. It is possible to operate an automatic power

up of the UID when a wake up tone is detected

from the line by connecting the LSD output directly

to the Bx input.

GCI: when NT1-2 or LT configuration is selected

(M0 = 0), the UID is powered up after configura-

tion setting by the PUP code (0000) on C/I Chan-

nel.

Power down control

A control instruction PDN in ACT register is re-

quired to power down the device after a period of

activity. PDN forces directly the device to the low

power state without sequencing through any of

the de-activation states. It should therefore only

be used after the UID has been put in the line de-

activated state. PDN has no influence on the con-

tent of the internal registers, but immediately

stops the output clocks when UID is in master

mode and in

µW/DSI mode.

In GCI mode, UID send first two times code

DI(1111) on C/I channel before powering down at

the end of the assigned GCI channel.

The DI code purpose is similar to PDN code but

power down state is entered only when the line is

entirely deactivated (state H1 or J1). The DI com-

mand is recommended.

Power up state

Power up transition enables all analog and digital

circuitry, starts the crystal oscillator and internal

clocks. The LSD output is in the high impedance

state even if a tone is detected from the line. As

for PDN, PUP has no influence on the content of

the internal registers

Power down state

Following a period of activity in the power up

state, the power down state may be re-entered as

described above. Configuration Registers remain in

their current state. PDN and DI have no influence

on the content of the internal registers: it is then

possible, for instance, after a normal deactivation

procedure followed by a power down command, to

power up again the device in order to operate di-

rectly a Warm Start procedure.

ACTIVATION/DEACTIVATION SEQUENCING

Activation/deactivation signals onto the line are in

accordance with the activation/deactivation state

matrix given in Appendix A.

CASE OF RESTRICTED ACTIVATION

The standard specifies a mode where the U inter-

face can be turned on without the need to activate

the S/T interface provided this function is supported

at both ends of the loop. In this condition Mainte-

nance channel is available, typically for setting

loop-backs in the NT for error rate testing and other

diagnostics.

When this mode is enabled, bit M47 on the line in

LT to NT direction becomes the uoa bit. Setting

UAR activation command in the LT chip will set

uoa bit equal zero on the line. Detection of uoa bit

equal zero by the NT will inhibit activation of the

S/T interface. This results in SN3 signal in the NT

to LT direction, which causes generation of UAI

indication by the LT U device when superframe

synchronized.

If during restricted activation operation, a TE

starts to try activate the S/T interface by sending

info 1, the NT can pass this request to the LT via

M47 bit, the sai bit. This bit is set equal one by

writing AR command to the Activation Control

eration of an AP indication by the LT U device.

RESET OF ACTIVATION/DEACTIVATION STATE

MACHINE

When the device is either powered-up or down, a

control instruction RES resets the activation con-

troller ready for a cold start. That feature can be

used if the far-end equipment fails to warm start,

for example if the line card or NT has been re-

placed or if in a regenerator, the loss of synchro-

nisation of the second section imply the reset of

the first section for a further cold start. The con-

figuration registers remain in their selected value.

HARDWARE RESET

When GCI configuration is selected, pin RES acts

as a logical hardware Reset. The device is en-

tirely reset including activation/deactivation state

machine and configuration registers. Configura-

tion pins bias excluding MW define the eventual

new configuration. Pin MW must be maintained at

the 0 Volt for GCI configuration setting.

It is possible to operate a similar ”complete reset”

of UID by setting high bit RST in the RXOH com-

mand register. In this last case the Control inter-

face remains enabled. Refer to User guide for

Software reset procedure.

QUIET MODE

It is possible to force the device in a quiet mode in

which UID does not react to any line wake-up

tone and LSD pin remains high. There are two

STLC5412

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