U2350B-FP
TELEFUNKEN Semiconductors
Rev. A1, 29-May-96
1 (9)
PWM Speed Control for Permanent Excited DC Motors
Description
The monolithic integrated bipolar circuit U2350B is a
MOSFET or IGBT - control circuit which works on the
principle of pulse width modulation (PWM). The overall
concept enables the construction of a power controller
with mains voltage compensation where intermittent
operation is also possible. In addition, the circuit also
enables mains-voltage compensated current control,
which maintains the power supplied at a constant level
after the preset threshold has been exceeded.
Features
D Pulse width control up to 30 kHz clock frequency
D Mains supply compensation
D Current regulation
D Temperature monitoring with indicator
D Active operation indicator
D Blink-warn indicator
D Switchable to interval operation
D Push-pull output stage for separate supply
D Supply voltage monitoring
D Temperature compensated supply voltage limitation
Applications
D Domestic equipment
D Tools
Package: SO16
Block Diagram
Temperature
monitoring
Push pull
output
Output
control
PWM Control
Program
logic
Current
limitation
Temperature
monitoring
LED control
Tristate
Oscillator
Voltage limitation
8
6
7
5
12
15
14
13
10
9
11
GND
2
1
16
95 10873
+V
S
4
Figure 1. Block diagram
U2350B-FP
TELEFUNKEN Semiconductors
Rev. A1, 29-May-96
2 (9)
Normal
Stop
Multi
+V
S
open
Progr
.
logic
Oscillator
+
+
420 mV
350 mV
80%
100%
V
oltage
monitoring
Q
S
Q
R
S
3
Impedance
converter
Output
stage logic
Push
pull
stage
LED logic
Supply voltage
limitation
S
2
S
1
Comparator 1
+
+
+V
S
16
15
14
13
11
Comparator 2
1.2 V/
1.5 V
12
10
9
1
2
3
4
5
6
7
8
red
D
3
green
D
2
R
10
R
12
82 k
W
T
ristate switch
C
7
10 F/
35 V
R
11
120 k
W
C
3
220 nF
C
4
220 nF
R
13
NTC
R
5
100 k
W
C
5
680 nF
R
14
47 k
W
R
15
10 k
W
R
12
10 k
W
T
1
GND
R
8
0.22
W/
4 W
IGBT
M
D
1
BYT86
800
R
1
56 k
W/
2 W
47 F/
350 V
C
6
C
2
22 nF
R
7
5.6 M
W
R
6
180 k
W
R
9
120 k
W
C
1
10 nF
R
3
220 k
W
R
4
7.5 k
W
V
M
=
230 V~
95 10868
Speed
m
m
Figure 2. Block diagram with external circuit
U2350B-FP
TELEFUNKEN Semiconductors
Rev. A1, 29-May-96
3 (9)
Pin Description
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
n.c.
NTC
95 11409
Progr.
R
osc
C
osc
Contr.
LED1
LED2
OUT
OUT
GND
I
Contr.
S
1
V
Contr.
+V
S
OUT+
Pin
Symbol
Function
1
LED1
LED output 1
2
LED2
LED output 2
3
n.c.
Not connected
4
NTC
Monitoring input
5
Progr.
Tristate programing
6
R
osc
Resistor for oscillator
7
C
osc
Capacitor for oscillator
8
Contr.
Control input
9
V
Contr.
Voltage regulation input
10
S
1
Switching output, output S1
11
I
Contr.
Current regulation input
12
GND
Ground
13
OUT
supply for output stage
14
OUT
Output
15
OUT+
+ supply for output stage
16
+V
S
Supply voltage
Supply, Pin 16
The internal voltage limiter in the U2350B enables a
simple supply from the rectified line voltage. The supply
voltage between Pin 16 (+V
S
) and Pin 12 (ground) is built
up via R
1
and is smoothed by C
7
. The typically 5 mA
supply current is simultaneously used to operate the two
LEDs D
2
, D
3
, which can both be bridged internally. The
supply current therefore reaches Pin 16 either via LEDs
or the internal switches (V
sat
1.2 V).
Series resistor, R
1,
can be calculated as follows:
R
1max
+
V
Mmin
V
Smax
I
tot
whereas
V
Mmin
+ V
mains
15%
V
Smax
+ maximum supply voltage
I
tot
+ I
Smax
) I
x
I
Smax
+ Max. current consumption of the IC
I
x
+ Current consumption of the external components
Here, C
6
must be selected in this way that the voltage at
C
7
(figure 2) is not noticeably affected by the load in any
mode of operation. For further information regarding
mains power supply, refer to figures 6 and 7.
Voltage Monitoring
Whilst the operating voltage is being built up or reduced,
uncontrolled output pulses of insufficient amplitude are
suppressed by the internal monitoring circuit. The latch
is also reset, the LED D
2
(operating indicator) between
Pin 2 and Pin 16 is switched off and the control input
"Pin 8" is connected to ground via switch S
3
and a 1 k
W
resistor. In connection with a switching hysteresis of
approximately 2 V, this mode of operation guarantees
fail-safe start-up each time the operating voltage is
switched on, in the same way as after short mains
interruptions.
Connecting the control input Pin 8 with a capacitor can
therefore make a soft start with rapid recovery possible.
Pulse Width Control with Mains Voltage
Compensation, Pins 8, 9, 10
Average value of the voltage over the load is controlled
to an infinitely selectable value by the comparator
Comp.
1
with hysteresis. The rectified mains voltage is
divided by R
3
and R
4
and lead in Pin 10. The capacitor C
1
is charged via R
9
until the voltage V
9
, which is present at
the inverting input of Comp. 1, is more positive than the
control voltage V
8
arriving at the non-inverting input via
an impedance converter. During the charge time, which
is dependent of the mains voltage, the pulse output is at
high potential and the switching output Pin 10 is open. If
V
9
now becomes greater than V
10
, the output from
Comp. 1 switches over the output stage logic via an AND
gate.
U2350B-FP
TELEFUNKEN Semiconductors
Rev. A1, 29-May-96
4 (9)
The output stage logic now brings V
14
to low potential
and closes the switching output Pin 10. This has the effect
of discharging C
1
via R
9
and the switch S
1
until the
approximately 300 mV hysteresis of the comparator is
completed. The discharge time is dependent on the
control voltage V
8
.
Comp. 1 then switches over again and the cycle begins
once more (see figure 3). This two-state controller
compensates the influence of the mains voltage, with the
result that the motor voltage or motor speed is largely
determined by the magnitude of the control voltage.
Current Control, Pin 11
If the current flowing through the IGBT (or MOSFET)
and the shunt resistor R
8
becomes so high that a voltage
higher than 1.5 V arises at Pin 11, a second control loop
formed with the comparator Comp. 2 becomes active,
and overrides the first control loop via an AND gate. This
causes the average value of the current, fed to the motor,
to be controlled to a constant value. This in turn results in
a speed which decreases greatly with the increasing
torque (see figure 4).
V
9
V
10
V
14
t
95 10869
Figure 3. Pulse width control signal characteristics
Speed
(of rotation)
Torque
V
8
I
max
95 10870
Figure 4. Influence of current control on the characteristic
(curve) of a motor
By exceeding the maximum current which is adjustable
with R
8
, the control dependent voltage V
8
(shunt
characteristic) reaches the dotted lines (series
characteristic). By applying a current which depends on
the load voltage across R
6
, the constant value of the
current can be further influenced. In addition, the current
control limits the starting current.
In the case of effective current limiting, alteration of the
rectified mains voltage has an effect on the power taken
up. In order to compensate for this influence, the resistor
R
7
is connected to Pin 11. If dimensioned appropriately,
the consumed power is independent of changes in the
mains voltage within a wide range of this voltage.
Operation Mode Selection, Pin 5
It is possible to program three modes of operation with the
tristate input, as follows:
a)
Intermittent operation (Pin 5 connected to +V
S
)
A signal emitted by an internal oscillator (see
figure 5) switches the output stage ON and OFF
periodically via S
2
. This intermittent operation is
very suitable for certain uses.
b) Stop function (Pin 5 open)
The output is continuously switched off, the motor is
at reset.
c)
Normal function (Pin 5 connected to V
12
)
The motor runs continuously.
Temperature Monitoring, Pin 4
The circuit also has a monitoring input. If a NTC-resistor
is connected to this input, for example, it functions as a
temperature sensor. If the voltage V
4
falls below the first
threshold V
T80
(approximately 420 mV) as a result of the
increasing temperature, an external LED D
3
, which is
connected between Pin 1 and Pin 2, starts to blink. If the
temperature increases further and the voltage V
4
falls
below a second threshold V
T100
(approximately
350 mV), a latch is set. The latch makes this LED light up
continuously, the output stage is blocked. The motor is
switched-OFF and remains switched-OFF until the
temperature has fallen and until the mains voltage is
switched-OFF and switched-ON again (the latch is solely
reset by the voltage monitoring). A second LED D
2
,
which is connected between Pin 2 and Pin 16 and which
is continuously illuminated (switch-ON) during normal
operation, is switched-OFF.
In the event of wire breakage in the sensor branch, Pin 4
is pulled up to +V
S
. After the switch-OFF threshold
V
TOFF
(approximately V
S
1.8 V) has been exceeded, the
circuit ensures that the latch is set here too. This
guarantees safe operation.
U2350B-FP
TELEFUNKEN Semiconductors
Rev. A1, 29-May-96
5 (9)
Absolute Maximum Ratings
Reference point Pin 12, unless otherwise specified.
Parameters
Symbol
Value
Unit
Supply Current
Pin 16
t
10
ms
I
S
i
s
30
60
mA
Push-pull output
V
13
V
14
V
15
, V
15
V
16
, V
13
V
12
Output current
t
2 ms
I
O
i
o
20
200
mA
Signal outputs
Input current
t
10
ms
I
I
i
i
30
60
mA
Input currents
Pin 6, 8
Pin 10
I
I
1
10
mA
Input voltages
Pin 4, 5, 7, 9, 10, 11
V
I
0 V to V
16
Storage temperature range
T
stg
40 to +125
C
Junction temperature
T
j
+125
C
Ambient temperature range
T
amb
10 to +100
C
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient
DIP16
SO16 on PC board
SO16 on ceramic
R
thJA
120
180
100
K/W
K/W
K/W
Electrical Characteristics
V
S
= 15.5 V, T
amb
= 25
C, reference point Pin 12, figure 2, unless otherwise specified.
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Supply voltage limitation
I
S
= 5 mA
Pin 16
I
S
= 20 mA
V
S
16.2
16.3
17.2
17.8
V
Current consumption
I
S
3.5
mA
Voltage monitoring
Pin 16
Switch-on threshold
V
SON
14.0
14.5
V
Switch-off threshold
V
SOFF
12.0
12.5
V
Control input
Pin 8
Input voltage range
V
I
0
7.5
V
Input quiescent current
I
IB
250
nA
Impedance at lower voltage
R
I
1
k
W
Comparator 1
Pin 9
Input voltage range
V
IC
0
7.5
V
Input quiescent current
I
IB
250
nA
Hysteresis
V
8
= 1.5 V
Pin 8 9
V
hys
270
300
330
mV
Delay time
Pin 9 14
t
d
3
ms
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