SI3230 SILABS [Silicon Laboratories], SI3230 Datasheet - Page 19

• Manufacturer Part Number: SI3230
• Manufacturer: SILABS [Silicon Laboratories]

order to monitor the linefeed current. R
R
sense circuitry is calibrated on-chip to guarantee
measurement
component
Calibration" on page 23 for details.
2.1.3. Linefeed Operation States
The ProSLIC linefeed has eight states of operation as
shown in Table 20. The state of operation is controlled
using the Linefeed Control register (direct Register 64).
The open state turns off all currents into the external
bipolar transistors and can be used in the presence of
fault conditions on the line and to generate Open Switch
Intervals (OSIs). TIP and RING are effectively tri-stated
with a dc output impedance of about 150 kΩ. The
ProSLIC can also automatically enter the open state if it
detects excessive power being consumed in the
external
Monitoring and Line Fault Detection" on page 20 for
more details.
In the forward active and reverse active states, linefeed
circuitry is on and the audio signal paths are powered
down.
In the forward and reverse on-hook transmission states
audio signal paths are powered up to provide data
transmission during an on-hook loop condition.
Note: The Linefeed register (LF) is located in direct Register 64.
BAT
LF[2:0]*
000
001
010
100
101
011
110
111
provide access to these measuring points. The
bipolar
tolerances.
accuracy
Forward On-Hook Transmission
Reverse On-Hook Transmission
transistors.
Linefeed State
Forward Active
Reverse Active
Ring Open
TIP Open
with
See
Ringing
Open
See
Table 20. ProSLIC Linefeed Operations
standard
"2.1.9.
"2.1.5.
DC
, R
Preliminary Rev. 0.96
Linefeed
external
SE
Power
, and
TIP and RING tri-stated.
V
V
TIP tri-stated, RING active; used for ground start.
Ringing waveform applied to TIP and RING.
V
V
RING tri-stated, TIP active.
TIP
TIP
RING
RING
The TIP Open state turns off all control currents to the
external bipolar devices connected to TIP and provides
an active linefeed on RING for ground start operation.
The RING Open state provides similar operation with
the RING drivers off and TIP active.
The
waveforms onto the line.
2.1.4. Loop Voltage and Current Monitoring
The ProSLIC continuously monitors the TIP and RING
voltages and external BJT currents. These values are
available in registers 78–89. Table 21 on page 20 lists
the values that are measured and their associated
registers. An internal A/D converter samples the
measured voltages and currents from the analog sense
circuitry and translates them into the digital domain. The
A/D updates the samples at an 800 Hz rate. Two
derived values are also reported—loop voltage and loop
current. The loop voltage, V
1-bit sign, 6-bit magnitude format. For ground start
operation the reported value is the RING voltage. The
loop current, (I
bit sign, 6-bit magnitude format. In RING open and TIP
open states the loop current is reported as (I
(I
Q5
> V
> V
> V
> V
–I
RING
RING
Q6
ringing
TIP
TIP
).
.
.
; audio signal paths powered on.
; audio signal paths powered on.
Q1
state
– I
Description
Q2
drives
+ I
Q5
TIP
–I
– V
Q6
programmable
)/2, is reported in a 1-
RING
, is reported as a
Si3230
Q1
– I
ringing
Q2
) +
19