ATMEL U209B User Manual

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Phase-Control IC – Tacho Applications

Description

The integrated circuit U209B is designed as a phase­control circuit in bipolar technology with an internal
frequency-voltage converter. Furthermore, it has an
internal open-loop amplifier which means it can be used
for motor speed control with tacho feedback.

Features

 Internal frequency-to-voltage converter

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.

 Triggering pulse typ. 155 mA

U209B

 Externally controlled integrated amplifier
 Automatic soft start with minimized “dead time”
 Voltage and current synchronization
 Retriggering

Block Diagram

14(16) 1(1)

Voltage / Current

detector

10(10)

9(9)

+

–

Control
amplifier

Automatic

retriggering

Phase

control unit



= f (V11)

 Internal supply-voltage monitoring
 Temperature-compensated reference source
 Current requirement ≤ 3 mA

Output

pulse

Supply
voltage

limitation
Reference

voltage

Voltage

monitoring

4(4)

5(5)

6(6)

3(3)

2(2)

13(15)

–V

GND

S

Frequency-

Soft start

–V

S

11(11) 12(12) 8(8) 7(7)

Figure 1. Block diagram (Pins in brackets refer to SO16)

to-voltage

converter

U209B

Ordering Information

Extended Type Number Package Remarks

U209B-x DIP14 Tube

U209B-xFP SO16 Tube

U209B-xFPG3 SO16 Taped and reeled

Rev. A3, 11-Jan-01 1 (11)

U209B

L

=

M

V

230 V ~

N

M

F

2

C

3

Supply

F

25 V

22

1

C

S

–V

2

voltage

16 V

2.2

10

C

GND

voltage

limitation

Reference

13

Voltage

monitoring

U209B

converter

to voltage

Frequency

220 nF

4

C

5

C

Speed sensor

R

1 k 

1 nF

5

1

1

R

TIC

236N



2 W

18 k

IN4007 D

13

R

4

Output

220 

pulse

680 k

2

3.3 nF

R

6

5

)

11

Automatic

retriggering



4

R

470 k

Phase

= f (V



control unit

Soft start

s

–V

8

C

11 12 8 7

F

3

2.2

C

220 nF

7

R

16 V



22 k

R

3



220 k

14 1

9



R

47 k

detector

Voltage / Current

R

Set speed

voltage

12

R

100 k 

11

10

R



100 k



56 k

Control

amplifier

10

9

C

–

+

9

F

2.2 /16 V

Figure 2. Block diagram with typical circuitry for speed regulation

7

C

F

16 V

2.2



8

R

Actual

2 M

speed

voltage



6

R

68 k

6

C

100 nF

Rev. A3, 11-Jan-012 (11)

Description

Mains Supply

The U209B is designed 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 D
series resistance can be approximated using:

Further information regarding the design of the mains
supply can be found in the chapter “Design Calculations
for Mains Supply”. The reference voltage source on Pin
13 of typ. –8.9 V is derived from the supply voltage and
represents the reference level of the control unit.

Operation using an externally stabilised DC voltage is not
recommended.

If the supply cannot be taken directly from the mains
because the power dissipation in R
then the circuit shown in the following figure 3 should be
employed.

and R1 and is smoothed by C

1

1



VM–V

R

2I

S

S

~

24 V~

12345

U209B

. The value of the

1

would be too large,

1

U209B

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 C
of C2 and hence the pulse width can be evaluated by
assuming 8 s/nF).

The current sensor on Pin 1 ensures that no pulse is gener­ated (for operation with inductive loads) in a new half
cycle as long as the 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 V

= –7 V, the phase angle is at maximum = 

11

the current flow angle is a minimum. The minimum phase
angle 

is when V

min

11

= V

pin2

.

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 behaviour each time the supply
voltage is switched on or after short interruptions of the
mains supply.

Soft Start

(the value

2

, i.e.,

max

As soon as the supply voltage builds up (t1), the integrated
soft start is initiated. Figure 4 shows the behaviour of the

R

1

C

1

voltage across the soft-start capacitor which is identical

Figure 3. Supply voltage for high current requirements

with the voltage on the phase control input on Pin 11. This
behaviour guarantees a gentle start-up for the motor and
automatically ensures the optimum run-up time.

Phase Control

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. This 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 C
current. The charging current can be varied using R
Pin 5. The maximum phase angle 
justed using R2.

and its charging

2

can also be ad-

max

on

2

is first charged up to the starting voltage V

3

typically 30 A current (t2). By then reducing the
charging current to approx. 4 A, the slope of the charging
function is substantially reduced so that the rotational
speed of the motor only slowly increases. The charging
current then increases as the voltage across C
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 A.

with

o

increases

3

C

Rev. A3, 11-Jan-01 3 (11)

U209B

V

C3

V

12

V

0

t

1

t

2

Figure 4. Soft start

t

3

t

tot

t

t1 = build-up of supply voltage
t2 = charging of C3 to starting voltage
t1 + t2 = dead time
t3 = run-up time
t

= total start-up time to required speed

tot

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 typ.
–100 mV gives very reliable operation even when
relatively simple tacho generators are employed. The
tacho frequency is given by:

n

f =

n = revolutions 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 C
amplified and then integrated by C
output on Pin 9. The conversion constant is determined
by C5, its charging voltage of Vch, R
internally adjusted charge amplification Gi.

k = Gi  C5  R

 V

6

The analog output voltage is given by

V

= k  f

where: V

o

= 6.7 V

ch

G

= 8.3

i

p[Hz]

60

is internally

5

at the converter

6

(Pin 9) and the

6

ch

The values of C

and C6 must be such that for the highest

5

possible input frequency, the maximum output voltage V
does not exceed 6 V. The R
C

is charging up. To obtain good linearity of the

5

on Pin 8 is approx. 6 kΩ while

i

f/V converter the time constant resulting from Ri and C
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 C5, C

and the internal

6

charge amplification.

V



O

The ripple ∆V

Gi Vch C

C

can be reduced by using larger values of

o

5

6

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)
which always tries to hold the real voltage at the value of
the set voltages. The amplifier has a transmittance of typi­cally 110 A/V and a bipolar current source output on Pin
11 which operates with typically ±100 A. The
amplification and frequency response are determined by
R7, C7, C
power divider, C4, C5, R6, C6, R7, C7, C

and R8 (can be left out). For operation as a

8

and R8 can be

8

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 V

13

+ 1 V.

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 I

GT

= f (R

GT

) can

be taken from figure 14.

Automatic Retriggering

The automatic retriggering prevents half cycles without
current flow, even if the triacs are 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.

0

5

Rev. A3, 11-Jan-014 (11)