U4078B Datasheet, PDF (4/5 Pages) TEMIC Semiconductors – Tone Ringer Interface with DC/DC Converter

U4078B
TELEFUNKEN Semiconductors
Time Sequence
Internal clock frequency without RC tolerance
t_clock
t_pulse
During this time, a clock signal is given at
Pin 5 (ST).Pin 4 is open or ST is high ohmic.
(MS=GND)
By every polarity change of the call signal and MS
open, the clock signal is interrupted for a time
duration
t_pulse = 32/f_clock. During interruption, the signal at
ST (Pin5) is of such a value that the coil is critically
attenuated (damped).
[ I_S (PNP) = I_ST 10 µA
x A current of I_ST 150 µA is drawn from Pin 5 (ST) by
every polarity change whereby MS is grounded.
Call signal
ST
MS = open
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ST
MS = 0
t_cycle t_puls
92 7461 e
e
t
ST
1. Phase
2. Phase
1
f_cycle
t
92 7471 e
Current sequence at Pin 5 with an external PNP transistor connected as shown in figure 1. (f_clock = 38 kHz)
Ordering Information
Package
SO8
Type
U4078B-FP
Dimensions in mm
Package: SO8
4