U4080B Datasheet, PDF (11/15 Pages) TEMIC Semiconductors – Voice-Switched Circuit for Handsfree Operation

40
30
T_amb = 25 °C
20
10
100 mW
80 mW
50 mW
20 mW
5 mW
U4080B
40
30
T_amb = 25 °C
20
Allowable operating
voltage range
10
0
4
6
8
10
12
94 7878 e
V₁₆ ( V )
Figure 13.
" ^{VCC (Pin 20) is a regulated output voltage of}
5.4 V 0.5 V. Regulation will be maintained as long as
V+ is (typically) 80 mV greater than the regulated value
x ^{of VCC. Up to 3 mA can be sourced from this supply for}
external use. The output impedance is 20 Ω. The 47 µF
capacitor indicated for connection to Pin 20 is essential
for stability reasons. It must be located adjacent to the IC.
If the circuit is deselected (see the section on chip select),
the V_CC voltage will go to 0 V.
If the integrated circuit, U4080B, is to be powered from
a regulated supply (not the Tip and Ring lines) of less than
6.5 V, the configuration of figure 14 may be used so as to
ensure that V_CC is regulated. The regulated voltage is
applied to both V+ and V_CC, with CS held at a logic 1 so
as to turn off the internal regulator (the Chip Select
function is not available when the circuit is used in this
manner). Figure 15 indicates the supply current by this
configuration, with no signal at the speaker. When a
signal is sent to the speaker the curves of figure 13 apply.
0
4
5
6
7
8
94 7879 e
V+ ( V )
Figure 15.
V_B
" ^{VB is a regulated output voltage with a nominal value of}
2.9 V 0.4 V. It is derived from V_CC and tracks it,
holding a value of approximately 54% of V_CC. 1.5 mA
can be sourced from this supply at a typical output
impedance of 250 Ω. The 47 µF capacitor indicated for
connection to the V_B pin is required for stability reasons,
and must be adjacent to the IC. If the circuit is deselected
(see section on chip select), the V_B voltage will go to 0 V.
Chip Select
The Chip Select pin (Pin 18) allows the chip to be pow-
ered down anytime its functions are not required. A logic
1 level in the range of 1.6 to 11 V deselects the chip, and
y ^{the resulting supply current (at V+) is shown in figure 12}
The input resistance at Pin 18 is 75 kΩ. The V_CC and
the V_B regulated voltages go to zero when the chip is
deselected. Leaving Pin 18 open is equivalent to a logic
O (chip enabled).
U 4080 B
22 20 18 16
V+
200 mF
94 7883 e
Figure 14. Regulated power supply
TELEFUNKEN Semiconductors
Rev. A1, 20-May-96
Preliminary Information
11 (15)