PBL38640-2 데이터 시트보기 (PDF) - Ericsson

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PBL38640-2

Subscriber Line Interface Circuit

Ericsson  

PBL 386 40/2

R

S TIPX

VBExt

PBL 386 40/2

RLRTo

RINGX

Figure 7. Tipx voltage.

Notes

1. The overhead voltage can be adjusted with the ROV

resistor for higher levels e.g. min 3.1 VPeak and is specified

at the two-wire port with the signal source at the four-wire

receive port.

2. The two-wire impedance is programmable by selection of

external component values according to:

ZTRX = ZT/|G2-4S α RSN| where:

ZTRX = impedance between the TIPX and RINGX

terminals

Z = programming network between the VTX and RSN

T

terminals

G2-4S = transmit gain, nominally = 1 (or 0.5 see pin PTG)

α RSN = receive current gain, nominally = 200 (current

defined as positive flowing into the receive summ-

ing node, RSN, and when flowing from ring to tip).

3. Higher return loss values can be achieved by adding a

reactive component to RT, the two-wire terminating

impedance programming resistance, e.g. by dividing RT

into two equal halves and connecting a capacitor from the

common point to ground.

4. The overhead voltage can be adjusted with the ROV

resistor for higher levels e.g. min 3.1 VPeak and is specified

at the four-wire transmit port, VTX, with the signal source

at the two-wire port. Note that the gain from the two-wire

port to the four-wire transmit port is G2-4S = 1 (or 0.5 see

pin PTG)

5. Pin PTG = Open sets transmit gain to nom. 0.0dB

Pin PTG = AGND sets transmit gain to nom. -6.02 dB

Secondary protection resistors RF impact the insertion

loss as explained in the text, section Transmission. The

specified insertion loss is for RF = 0.

6. The specified insertion loss tolerance does not include

errors caused by external components.

7. The level is specified at the two-wire port.

8. The two-wire idle noise is specified with the port

terminated in 600 Ω (RL) and with the four-wire receive

port grounded (ERX = 0; see figure 6).

The four-wire idle noise at VTX is specified with the two-

wire port terminated in 600 Ω (RL). The noise

specification is referenced to a 600 Ω programmed two-

wire impedance level at VTX. The four-wire receive port is

grounded (ERX = 0).

9. Previous state must be active - loop or ground key

detector.

10. If |VBExt| ≥ |VBat + 2 V|, where VBat is the voltage at VBAT pin,

the current ILeak is limited to ≈ 5mA.

7

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