UBA1707 Ver la hoja de datos (PDF) - Philips Electronics
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UBA1707 Datasheet PDF : 36 Pages
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Philips Semiconductors
Cordless telephone, answering machine
line interface
Product specification
UBA1707
The UBA1707 offers the possibility to choose two kinds of
regulations for the DC characteristic between the line
terminals LN+ and LN− (see Fig.7):
• Voltage regulation mode
• Current regulation mode.
handbook, halfpage
Vline
(1)
(2)
(3)
Iline
Ilow
Iknee
Iprot (4)
MGK710
(1) Low voltage area.
(2) Small slope (determined by RSLPE).
(3) Small slope (dashed line; determined by RSLPE) in voltage
regulation mode.
High slope (full line; determined by RSLPE, RLVI and RRGL) in
current regulation mode.
(4) Current limitation.
Fig.7 General form of the DC mask as a function
of regulation mode.
Therefore VCE (TNSW) ≅ RLVI × ILVIV = 200 mV in typical
application (see Fig.18).
The slope ∆Vline/∆Iline of the Vline, Iline characteristic is
RREGV ≅ RSLPE.
Current regulation mode
In current regulation mode (bit CRC at logic 1), when the
line current is lower than Iknee = 35 mA (with
ZSET = 619 Ω), VCE (TNSW) is fixed by means of a 200 nA
DC constant current ILVIV flowing through RLVI. When the
line current is higher than 35 mA, an additional current
(proportional to the line current) flows through RLVI. As a
result, TNSW works as a DC voltage source increasing with
the line current. VCE (TNSW) can be calculated as follows:
VCE
( TNSW)
≅ RLVI ×
R--R---S-R--L-G--P--L-E-
×
( Iline
– Iknee)
+
ILVIV
Where:
Iline = line current
RRGL = resistor connected at pin RGL.
The slope ∆Vline/∆Iline of the Vline, Iline characteristic is
determined by the ratio of resistors connected at
pins SLPE, LVI and RGL, and can be calculated as
follows: RREGC ≅ RSLPE + RLVI × R--R---S-R--L-G--P--L-E- = 1400 Ω in
typical application (see Fig.18).
Current limitation
Whatever the selected mode is, the line current is limited
to approximately 145 mA. This current is sensed on SLPE,
for this purpose the external zener diode must be
connected between pins LN and SLPE. The speech
function no longer operates in this condition.
The regulation mode is selected by the bit CRC via the
serial interface.
The DC mask regulation is realised by adjusting the DC
voltage VCE (TNSW) between pin GND and line terminal
LN− as a function of the line current.
Voltage regulation mode
In voltage regulation mode (bit CRC at logic 0),
VCE (TNSW) voltage is fixed by means of a 200 nA DC
constant current ILVIV flowing through RLVI.
ELECTRONIC HOOK SWITCH CONTROL (PIN EHI)
The electronic hook switch input (EHI) controls the state of
TPDARL transistor. When the voltage applied at pin EHI is
LOW, TPDARL transistor is turned off. Voltage at pin LCC is
pulled up to supply voltage (VCC). TNSW and TNON-HOOK
transistors are also turned off by means of a pull-down
resistor (RPLD). When the voltage applied at pin EHI is
HIGH, TPDARL transistor is driven by the operational
amplifier at pin LCC and the regulation mode selected is
operating. An internal 165 kΩ pull-up resistor is connected
between pins LCC and VCC.
1999 Feb 17
10
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