
1996 Sep 04
11
Philips Semiconductors
Product specication
Light position controller
TDA3629
Application diagrams and additional information
Two possible application diagrams are shown. The first
(see Fig.9) shows the best case: the lowest component
count. The second (see Fig.10) shows additional
components which may be necessary. Two capacitors are
added to meet EMC requirements (one on the VP pins, the
second one between the set and feedback input pins).
A third capacitor has been added across the motor to
suppress current spikes. The given values of these
capacitors have to be optimized by experiments carried
out on the total application. The resistors do not have to
have the same value. The voltage hysteresis is set by
means of RSET.
The resistor in the feedback input line (RFB) is present to
limit the current during the transients as illustrated in Figs 7
and 8. This resistor should have a value larger than 2 k
.
RSET can be chosen freely but must also be larger than
2 k
. A diode is placed in series with the supply line in both
applications to protect the device from reverse polarity
switching and from damage caused by pulses 1 and 3 in
Figs 7 and 8. In the present application a varistor is
included in the motor. The electrolytic capacitor of 47
F
should have a very low ESR, for instance as low as 5
at
a temperature of
40 °C. An extra ceramic capacitor
(approximately 100 nF) parallel to it is obligatory when this
can not be guaranteed.
Fig.9 Best case application diagram.
handbook, full pagewidth
MGE640
INPUT
STAGE
SHORT-CIRCUIT
SUPPLY
BROKEN WIRE
PROTECTION
- OVER VOLTAGE
- UNDER VOLTAGE
- TEMPERATURE
WINDOWS
AND
COMPARATORS
VP
VP1
VP2
VP
OUT1
OUTPUT
STAGES
OUT2
SET
1 k
2.2 k
FB
ISET
RSET
RFB
ISET
TDA3629
+Vb
VSET
+
VFB
+
M
Vm
+
MECHANICAL
TRANSMISSION
43 V
47
F
Im
Iref