Features
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Internal Frequency-to-voltage Converter
Externally Controlled Integrated Amplifier
Automatic Soft Start with Minimized “Dead Time”
Voltage and Current Synchronization
Retriggering
Triggering Pulse Typically 155 mA
Internal Supply-voltage Monitoring
Temperature-compensated Reference Source
Current Requirement ≤3 mA
Phase Control
IC for Tacho
Applications
Electrostatic sensitive device.
Observe precautions for handling.
Description
The integrated circuit U209B is designed as a phase-control circuit in bipolar technology with an internal frequency-to-voltage converter. The device includes an internal
open-loop amplifier, which means it can be used for motor speed control with tacho
feedback.
U209B
The U209B is a 14-pin shrink version of the U211B with reduced features. Using the
U209B, the designer is able to realize sophisticated as well as economic motor control
systems.
Figure 1. Block Diagram
14(16)
1(1)
Automatic
retriggering
Voltage/Current
detector
4(4)
Output
pulse
5(5)
10(10)
+
6(6)
Control
amplifier
Phase
3(3)
9(9)
ϕ = f (V11)
-
-VS
Supply
voltage
limitation
control unit
Reference
voltage
2(2)
GND
13(15)
Voltage
monitoring
Soft start
Frequencyto-voltage
converter
U209B
-VS
11(11)
12(12)
8(8)
7(7)
Pin numbers in brackets refer to SO16 Package
Rev. 4765A–INDCO–01/04
2
R 10
56 k Ω
100 kΩ
R12
R9
47 k Ω
Actual
speed
voltage
2.2 µF/16 V
C9
R 11
100 k Ω
C6
9
10
100 nF
Set speed
voltage
R8
R6
68 k Ω
C7
2.2 µF
16 V
Control
amplifier
R4
-V s
22 k Ω
R7
220 nF
2.2 µF
16 V
C5
8
7
Frequencyto-voltage
converter
1 nF
C3
12
Soft start
Phase
control unit
ϕ = f (V 11)
Automatic
retriggering
C8
470 k W
11
1
Voltage/Current
detector
2 MΩ
-
+
14
R3
220 kΩ
R5
1 kΩ
C4
220 nF
U209B
Voltage
monitoring
Reference
voltage
Supply
voltage
limitation
Output
pulse
13
220 Ω
R13
C2
Speed sensor
GND
C1
C 10
3.3 nF
R 2 680 k Ω
2 -V S
3
6
5
4
18 k Ω
2W
2.2 µF
16 V
22 µ F
25 V
R1
D1
M
N
VM =
230 V ~
L
Figure 2. Block Diagram with Typical Circuitry for Speed Regulation
U209B
4765A–INDCO–01/04
U209B
Pin Configuration
Figure 3. Pinning DIP14
Isync
GND
-VS
Output
VRP
CP
F/V
1
2
3
4
5
6
7
14
13
12
11
10
9
8
Vsync
VRef
Csoft
CTR/OPO
OP+
OPCRV
Pin Description
Pin
Symbol
Function
1
Isync
2
GND
3
-VS
4
Output
Trigger pulse output
5
VRP
Ramp current adjust
6
CP
Ramp voltage
7
F/V
Frequency-to-voltage converter
8
CRV
Charge pump
9
OP-
OP inverting input
Current synchronization
Ground
Supply voltage
10
OP+
OP non-inverting input
11
CTR/OPO
Control input/OP output
12
Csoft
Soft start
13
VRef
Reference voltage
14
Vsync
Voltage synchronization
3
4765A–INDCO–01/04
Figure 4. Pinning SO16
Isync
GND
-VS
Output
VRP
CP
F/V
CRV
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
Vsync
VRef
OVL
Isense
Csoft
CTR/OPO
OP+
OP-
Pin Description
4
Pin
Symbol
Function
1
Isync
Current synchronization
2
GND
Ground
Supply voltage
3
-VS
4
Output
Trigger pulse output
5
VRP
Ramp current adjust
6
CP
Ramp voltage
7
F/V
Frequency-to-voltage converter
8
CRV
Charge pump
9
OP-
OP inverting input
10
OP+
OP non-inverting input
11
CTR/OPO
Control input/OP output
12
Csoft
Soft start
13
Isense
Load-current sensing
14
OVL
Overload adjust
15
VRef
Reference voltage
16
Vsync
Voltage synchronization
U209B
4765A–INDCO–01/04
U209B
Description
Mains Supply
The U209B is equipped with voltage limiting and can therefore be supplied directly from
the mains. The supply voltage between pin 2 (+ pol/⊥) and pin 3 builds up across D1 and
R1, and is smoothed by C1. The value of the series resistance can be approximated
using:
VM – V S
R 1 = -------------------2 IS
Further information regarding the design of the mains supply can be found in the section
“Design Calculations for Mains Supply” on page 9. The reference voltage source on
pin 13 of typically -8.9 V is derived from the supply voltage and represents the reference
level of the control unit.
Operation using an externally stabilized DC voltage is not recommended.
If the supply cannot be taken directly from the mains because the power dissipation in
R1 would be too large, the circuit as shown in Figure 5 should be used.
Figure 5. Supply Voltage for High Current Requirements
~
U209B
24 V~
1
R1
Phase Control
2
3
4
5
C1
The function of the phase control is largely identical to that of the well known integrated
circuit U2008B. The phase angle of the trigger pulse is derived by comparing the ramp
voltage (which is mains synchronized by the voltage detector) with the set value on the
control input pin 4. The slope of the ramp is determined by C2 and its charging current.
The charging current can be varied using R2 on pin 5. The maximum phase angle αmax
can also be adjusted by using R2.
When the potential on pin 6 reaches the nominal value predetermined at pin 11, a trigger pulse is generated whose width tp is determined by the value of C2 (the value of C2
and hence the pulse width can be evaluated by assuming 8 µs/nF).
The current sensor on pin 1 ensures that, for operation with inductive loads, no pulse is
generated in a new half cycle as long as a current from the previous half cycle is still
flowing in the opposite direction to the supply voltage at that instant. This makes sure
that “gaps” in the load current are prevented.
The control signal on pin 11 can be in the range 0 V to -7 V (reference point pin 2).
If V11 = -7 V, the phase angle is at maximum = αmax, i.e., the current flow angle is at
minimum. The minimum phase angle αmin is when V11 = Vpin 2.
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4765A–INDCO–01/04
Voltage Monitoring
As the voltage is built up, uncontrolled output pulses are avoided by internal voltage surveillance. At the same time, all latches in the circuit (phase control, soft start) are reset
and the soft-start capacitor is short-circuited. Used with a switching hysteresis of
300 mV, this system guarantees defined start-up behavior each time the supply voltage
is switched on or after short interruptions of the mains supply.
Soft Start
As soon as the supply voltage builds up (t1), the integrated soft start is initiated. Figure
6 shows the behavior of the voltage across the soft-start capacitor, which is identical
with the voltage on the phase control input on pin 11. This behavior guarantees a gentle
start-up for the motor and automatically ensures the optimum run-up time.
C3 is first charged up to the starting voltage Vo with typically 30 µA current (t2). By reducing the charging current to approximately 4 µA, the slope of the charging function is also
substantially reduced, so that the rotational speed of the motor only slowly increases.
The charging current then increases as the voltage across C3 increases giving a progressively rising charging function which accelerates the motor with increasing
rotational speed. The charging function determines the acceleration up to the set-point.
The charging current can have a maximum value of 50 mA.
Figure 6. Soft Start
VC3
V12
V0
t
t1
t3
t2
t tot
t1
t2
t1 + t2
t3
ttot
6
= build-up of supply voltage
= charging of C3 to starting voltage
= dead time
= run-up time
= total start-up time to required speed
U209B
4765A–INDCO–01/04
U209B
Frequency-to-voltage
Converter
The internal frequency-to-voltage converter (f/V converter) generates a DC signal on
pin 9 which is proportional to the rotational speed, using an AC signal from a tacho generator or a light beam whose frequency is in turn dependent on the rotational speed. The
high impedance input with a switch-on threshold of typically -100 mV gives very reliable
operation even when relatively simple tacho generators are employed. The tacho frequency is given by:
n
f = ------ p(Hz)
60
n = revolution per minute
p = number of pulses per revolution
The converter is based on the charge pumping principle. With each negative half wave
of the input signal, a quantity of charge determined by C5 is internally amplified and then
integrated by C6 at the converter output on pin 9. The conversion constant is determined
by C5, its charging voltage of Vch, R6 (pin 9) and the internally adjusted charge amplification Gi.
k = Gi × C5 × R6 × Vch
The analog output voltage is given by
where:
Vo = k × f
Vch = 6.7 V
Gi = 8.3
The values of C5 and C6 must be such that for the highest possible input frequency, the
maximum output voltage V0 does not exceed 6 V. The Ri on pin 8 is approximately 6 kΩ
while C5 is charging up. To obtain good linearity of the f/V converter the time constant
resulting from Ri and C5 should be considerably less (1/5) than the time span of the negative half cycle for the highest possible input frequency. The amount of remaining ripple
on the output voltage on pin 9 is dependent on C 5 , C 6 and the internal charge
amplification.
G i × V ch × C 5
∆V O = -----------------------------------C6
The ripple ∆Vo can be reduced by using larger values of C6, however, the maximum conversion speed will then also be reduced.
The value of this capacitor should be chosen to fit the particular control loop where it is
going to be used.
Control Amplifier
The integrated control amplifier with differential input compares the set value (pin 10)
with the instantaneous value on pin 9, and generates a regulating voltage on the output
pin 11 (together with external circuitry on pin 12). This pin always tries to keep the real
voltage at the value of the set voltages. The amplifier has a transmittance of typically
110 µA/V and a bipolar current source output on pin 11 which operates with typically
±100 µA. The amplification and frequency response are determined by R7, C7, C8 and
R8 (can be left out). For operation as a power divider, C4, C5, R6, C6, R7, C7, C8 and R8
can be left out. Pin 9 should be connected with pin 11 and pin 7 with pin 2. The phase
angle of the triggering pulse can be adjusted using the voltage on pin 10. An internal limiting circuit prevents the voltage on pin 11 from becoming more negative than V13 + 1 V.
7
4765A–INDCO–01/04
Pulse-output Stage
The pulse-output stage is short-circuit protected and can typically deliver currents of
125 mA. For the design of smaller triggering currents, the function IGT = f (RGT) can be
taken from Figure 15 on page 15.
Automatic Retriggering
The automatic retriggering prevents half cycles without current flow, even if the triacs
have been turned off earlier, e.g., due to not exactly centered collector (brush lifter) or in
the event of unsuccessful triggering. If necessary, another triggering pulse is generated
after a time lapse of tPP = 4.5 tP and this is repeated until either the triac fires or the half
cycle finishes.
General Hints and
Explanation of Terms
To ensure safe and trouble-free operation, the following points should be taken into consideration when circuits are being constructed or in the design of printed circuit boards.
The connecting lines from C2 to pin 6 and pin 2 should be as short as possible, and the
connection to pin 2 should not carry any additional high current such as the load current.
When selecting C2, a low temperature coefficient is desirable.
The common (earth) connections of the set-point generator, the tacho generator and the
final interference suppression capacitor C4 of the f/V converter should not carry load
current.
The tacho generator should be mounted without influence by strong stray fields from the
motor.
Figure 7. Explanation of Terms in Phase Relationship
V
Mains
Supply
π/2
π
3/2π
2π
VGT
Trigger
Pulse
tp
tpp = 4.5 tp
VL
Load
Voltage
ϕ
IL
Load
Current
Φ
8
U209B
4765A–INDCO–01/04
U209B
Design Calculations for
Mains Supply
The following equations can be used for the evaluation of the series resistor R1 for worst
case conditions:
V Mmin – V Smax
R 1max = 0.85 -------------------------------------2 Itot
V M – V Smin
R 1min = ---------------------------2 I Smax
2
( V Mmax – V Smin )
P ( R1max ) = --------------------------------------------2 R1
where:
VM = Mains voltage 230 V
= Supply voltage on pin 3
VS
= Total DC current requirement of the circuit
Itot
= IS + Ip + Ix
ISmax = Current requirement of the IC in mA
= Average current requirement of the triggering pulse
Ip
= Current requirement of other peripheral components
Ix
R1 can be easily evaluated from Figure 17 on page 16 to Figure 19 on page 16.
9
4765A–INDCO–01/04
Absolute Maximum Ratings
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Reference point pin 2, unless otherwise specified
Parameters
Current requirement
Pins
Symbol
Value
Unit
3
-IS
30
mA
t ≤10 µs
3
-is
100
mA
Synchronization current
1
IsyncI
5
mA
14
IsyncV
5
mA
t < 10 µs
1
±iI
35
mA
t < 10 µs
14
±iV
35
mA
Input current
7
Ieff
3
mA
t