ia3222 integration, ia3222 Datasheet - Page 20

• Manufacturer Part Number: ia3222
• Description: Ia3222/ia3223 Ez Daa? Chipset With Analog Interface
• Manufacturer: integration

Threshold Register
Note: The parallel-pickup threshold must be selected based on line usage and history. Depending on the application, selecting too
sensitive a threshold may falsely detect a parallel pickup in the presence of large signals. Setting 0 or 1 is recommended for voice
applications. Modem applications, where transmitted levels and frequency envelopes are well controlled, may benefit from using a
more sensitive setting. Refer to Figure 6, which indicates the sensitivity of the detection circuit for signals of different frequencies for
various settings. Note that the “high” headroom setting, (because of the reduced receiver gain), reduces the sensitivity of the
parallel-pickup function by 3 dB. Each setting is approximately twice as sensitive as the previous setting.
Line Status Register (Read Only)
Note: Writing any value to this register will reset all registers to their default values.
Notes:
Mnemonic
RNG [Note 1]
PPU [Note 1]
LIU [Note 1]
LD [Note 1]
LACT [Note 2]
LP [Note 1]
LTH1
RTH1
0
0
1
1
0
0
1
1
1.
2.
This bit is multiplexed to a digital output pin of the IA3223A.
In the on-hook state, LACT will become high if the line voltage change is at least 10 to 20V in either direction.
RTH0
LTH0
1
0
1
0
1
0
1
0
Definition
Ring signal
Parallel pickup
Line In Use
Line Drop
Line activity
Line polarity
No-Detection Ring Threshold (Vrms)
Line-disconnect detection (~2.5 V)
Line-in-Use Threshold (VDC)
22.5 ±7.5 V (reset state)
10 (reset state)
30 ±10V
15 ±5V
Applicability
On hook
Off hook
On hook
Off hook
On hook
Off hook
On hook and off hook
12.5
15
20
0: least sensitive (reset state)
Parallel-Pickup Threshold
Status When Bit is Low
Voltage below ring threshold
No loop-current drop
Voltage above LIU threshold
Line active
No change in line-in-use status
No parallel-pickup event
Line reversed
Ring Threshold (Vrms)
3: most sensitive
20 (reset state)
25
30
40
1
2
Change in line-in-use status
Parallel-pickup event
Status When Bit is High
Voltage above ring threshold
Loop-current drop
Voltage below LIU threshold
Line disconnected or line fault
Line direct
IA3222/IA3223
20