SI3225-G-GQ Silicon Laboratories Inc, SI3225-G-GQ Datasheet - Page 57

• Manufacturer Part Number: SI3225-G-GQ
• Description: IC PROSLIC/CODEC DUAL 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3225-G-GQ

• Function: Subscriber Line Interface Concept (SLIC), CODEC
• Interface: GCI, PCM, SPI
• Number Of Circuits: 2
• Voltage - Supply: 3.3V, 5V
• Current - Supply: 65mA
• Power (watts): 941mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-TQFP, 64-VQFP
• Includes: Battery Switching, BORSCHT Functions, DTMF Generation and Decoding, FSK Tone Generation, Modem and Fax Tone Detection
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The Si3220 can also add a dc offset component to the
ringing signal and detect a ring trip event by monitoring
the dc loop current flowing once the terminal equipment
transitions to the off-hook state. Although adding dc
offset reduces the maximum available ringing amplitude
(using the same ringing supply), this method is required
to reliably detect a valid ring trip event when sourcing
longer loop lengths. The dc offset can be programmed
from 0 to 64.32 V in the RINGOF RAM address as
required to produce adequate dc loop current in the off-
hook state. Depending on the loop length and the ring
trip method, the ac or dc ring trip detection circuits are
disabled by setting their respective ring trip thresholds,
RTACTH or RTDCTH, sufficiently high so that they do
not trip under any condition.
3.15.5. Si3225 Ring Trip Detection
The Si3225 implements an external ring trip detection
scheme when using a standard battery-backed external
ringing generator. In this application, the centralized
ringing generator produces an unbalanced ringing
signal that is distributed to individual TIP/RING pairs. A
per-channel ringing relay is required to disconnect the
Si3225 from the TIP/RING pair and apply the ringing
signal. By monitoring the ringing feed path across a ring
feed sense resistor (R
series with the ringing source, the Si3225 can detect the
dc current path created when the hook switch inside the
terminal equipment closes. The internal ring trip
detection circuitry is identical to that illustrated in
Figure 27. Figure 31 illustrates the typical external ring
trip circuitry required for the Si3225. Because of the
long loop nature of these applications, a dc ring trip
detection scheme is typically used. The user can
disable the ac ring trip detection circuitry by setting the
RTACTH threshold sufficiently high so it does not trip
under any condition.
3.16. Relay Driver Considerations
The Dual ProSLIC devices include up to three
dedicated relay drivers to drive external ringing and/or
test relays. Test relay drivers TRD1a, TRD1b, TRD2a,
and TRD2b are provided in all product versions, and
ringing relay drivers RRDa and RRDb are included for
the Si3225 only. In most applications, the relay can be
driven directly from the Dual ProSLIC with no external
relay drive circuitry required. Figure 28 illustrates the
internal relay driver circuitry using a 3 V or 5 V relay.
RING
in Figure 31 on page 60) in
Rev. 1.3
The internal driver logic and drive circuitry are powered
by the same V
(V
a V
diode network provides protection against overvoltage
conditions from flyback spikes when the relay is
opened. Either 3 V or 5 V relays can be used in the
configuration shown in Figure 28, and either polarized
or non-polarized relays are acceptable if the V
V
the relay driver pins is a constant 11 Ω while sinking
less than the maximum rated 85 mA into the pin.
If the operating voltage of the relay (V
the Dual ProSLIC V
circuit is required to eliminate leakage from V
through
configuration, a polarized relay will provide optimal
overvoltage
components. Figure 29 illustrates the required external
drive circuit, and Table 32 provides recommended
values for R
supplies. The output impedance, R
driver pins is a constant 63 Ω while sourcing less than
the maximum rated 28 mA out of the pin.
DD
Figure 28. Dual ProSLIC Internal Relay Drive
DD1
Si3220/
Si3225
CC
supplies are identical. The input impedance, R
–V
Driver
Relay
Logic
supply equal to the chip’s V
DD4
Si3220/25 Si3200/02
the
DRV
pins). When operating external relays from
DD
protection
internal
for typical relay characteristics and V
supply as the chip’s main V
GDD
V
DD
DD
Circuitry
supply voltage, an external drive
protection
and
TRD1a/b
TRD2a/b
RRDa/b
DD
minimal
supply, an internal
OUT
CC
V
diode.
CC
) is higher than
, of the relay
non-polarized)
3 V/5 V Relay
(polarized or
CC
DD
In
external
CC
to V
supply
IN
and
this
, of
DD
CC
57