L7556, L7557 Low-Power SLICs
with Battery Switch
Data Sheet
January 2000
Electrical Characteristics (continued)
Table 5. 2-Wire Port
Parameter
Min
Typ
Max
Tip or Ring Drive Current:
= dc + Longitudinal + Signal Currents
65
—
—
Signal Current
15
—
—
Longitudinal Current Capability per Wire1
8.5
15
—
dc Loop Current Limit2:
RLOOP = 100 Ω
Programmability Range
Accuracy (20 mA < ILIM < 40 mA)
—
ILIM
—
5
—
45
—
—
±12
Powerup Open Loop Voltage Levels (includes external diode):
Differential Voltage
|VBAT + 8.4| |VBAT + 7.9| |VBAT + 7.4|
Disconnect State:
PT Resistance (VBAT < VPT < 0 V)
PR Resistance (VBAT < VPR < 0 V)
100
143
—
100
133
—
Ground Start State:
PT Resistance
100
143
—
dc Feed Resistance (for ILOOP below regulation level)
95
115
135
Loop Resistance Range (–3.17 dBm overload into 600 Ω; not
including protection):
ILOOP = 20 mA at VBAT2 = –48 V
1885
—
—
ILOOP = 20 mA at VBAT2 = –24 V
685
—
—
Longitudinal to Metallic Balance—IEEE 3 Std. 455 (See
Figure 6.)4:
50 Hz to 1 kHz
1 kHz to 3 kHz
64
75
—
60
70
—
Metallic to Longitudinal Balance:
200 Hz to 4 kHz
46
—
—
RFI Rejection (See Figure 7.)5:
0.5 Vrms, 50 Ω Source, 30% AM Mod 1 kHz
500 kHz to 100 MHz
—
–55
–45
Unit
mA
mArms
mArms
mA
mA
%
V
kΩ
kΩ
kΩ
Ω
Ω
Ω
dB
dB
dB
dBV
1. The longitudinal current is independent of dc loop current.
2. Current-limit ILIM is programmed by a resistor, RPROG, from pin IPROG to DCOUT. ILIM is specified at the loop resistance where current limiting
begins (see Figure 19). Select RPROG (kΩ) =1.67 x ILIM (mA).
3. IEEE is a registered trademark of The Institute of Electrical and Electronics Engineers, Inc.
4. Longitudinal balance of circuit card will depend on loop series resistance matching (see Figure 23 and Figure 24).
5. This parameter is not tested in production. It is guaranteed by design and device characterization.
8
Lucent Technologies Inc.