Features
•
•
•
•
•
•
•
•
Full Wave Current Sensing
Compensated Mains Supply Variations
Variable Soft Start or Load-current Sensing
Voltage and Current Synchronization
Switchable Automatic Retriggering
Triggering Pulse Typically 125 mA
Internal Supply-voltage Monitoring
Current Requirement £ 3 mA
Applications
• Low-cost Motor Control
• Domestic Appliance
Description
The U2008B is designed as a phase-control circuit in bipolar technology. It enables
load-current detection as well as mains-compensated phase control. Motor control
with load-current feedback and overload protection are preferred applications.
Low-cost
Phase-control
IC with
Soft Start
U2008B
Figure 1. Block Diagram with Typical Circuit: Load Current Sensing
BYT51K
22 kW/2 W
230 V ~
R1
R2
330 kW
Load
D1
amax
7
Limiting
detector
R8
1 MW
6
Voltage
detector
Mains voltage
compensation
Automatic
retriggering
U2008B
Phase
control unit
Current
detector
TIC
226
R3
j = f(V3)
C1
Supply
voltage
limiting
8
180 W
1
Full wave load
current
detector
+
-
2
4
GND
Reference
voltage
C3
3.3 nF
R14
47 kW
3
R10
R6
22 µF/
25 V
Voltage
monitoring
Soft start
^
V(R6) = ±250 mV
-VS
5
C4
100 nF
100 kW
Set point
Load current
compensation
R7
P1
Rev. 4712A–AUTO–05/03
1
Figure 2. Block Diagram with Typical Circuit: Soft Start
230 V ~
BYT51K
22 kW/2W
L
R1
R2
D1
R8
amax
680 kW
470 kW
Load
7
Limiting
detector
6
Mains voltage
compensation
Voltage
detector
Automatic
retriggering
U2008B
Phase
control unit
Current
detector
TIC
226
R3
5
j = f(V3)
C1
Supply
voltage
limiting
8
180 W
1
Full wave load
current detector
+
-
2
Soft start
4.7 mF/25 V
100 mF/
25 V
4
GND
Reference
voltage
Voltage
monitoring
Soft start
C5
-VS
3
R10
68 kW
Set point
P1
50 kW
C3
10 nF
C4
100 nF
R7
220 kW
N
2
U2008B
4712A–AUTO–05/03
U2008B
Pin Configuration
Figure 3. Pinning
ISENSE
Cj
1
8
OUTPUT
2
7
VSYNC
U2008B
CONTROL
3
6
Rj
GND
4
5
- VS
Pin Description
Pin
Symbol
Function
1
ISENSE
Load current sensing
2
Cj
3
CONTROL
4
GND
Ground
5
-VS
Supply voltage
6
Rj
Ramp current adjustment
7
VSYNC
8
OUTPUT
Mains Supply, Pin 5,
Figure 2
Ramp voltage
Control input/compensation output
Voltage synchronization
Trigger output
The integrated circuit U2008B, which also contains voltage limiting, can be connected
via D1 and R1 to the mains supply. Supply voltage, between Pin 4 (pos., ^) and Pin 5, is
smoothed by C1.
The series resistance R1 can be calculated as follows:
VM – V Smax
R 1max = 0.85 ´ -----------------------------2 ´ I tot
where:
VM
VSmax
Itot
ISmax
Ix
= Mains voltage
= Maximum supply voltage
= ISmax + Ix = Total current compensation
= Maximum current consumption of the IC
= Current consumption of the external components
Operation with externally stabilized DC voltage is not recommended.
3
4712A–AUTO–05/03
Voltage Monitoring
When the voltage is built up, uncontrolled output pulses are avoided by internal voltage
monitoring. Apart from that, all latches of the circuit (phase control, load limit regulation)
are reset and the soft start capacitor is short circuited. This guarantees a specified startup behavior each time the supply voltage is switched on or after short interruptions of
the mains supply. Soft start is initiated after the supply voltage has been built up. This
behavior guarantees a gentle start-up for the motor and automatically ensures the optimum run-up time.
Phase Control, Pin 6
The function of the phase control is identical to that of the well-known IC U211B. The
phase angle of the trigger pulse is derived by comparing the ramp voltage V2 at Pin 2
with the set value on the control input, Pin 3. The slope of the ramp is determined by C3
and its charging current I j.
The charging current can be regulated, changed or altered using R8 at Pin 6. The maximum phase angle, a max, (minimum current flow angle jmin) can also be adjusted by
using R8 (see Figure 5).
When the potential on Pin 2 reaches the set point level of Pin 3, a trigger pulse is generated whose pulse width, tp, is determined from the value of C3 (tp = 9 µs/nF, see Figure
7). At the same time, a latch is set with the output pulse, as long as the automatic retriggering has not been activated, then no more pulses can be generated in that half cycle.
Control input at Pin 3 (with respect to Pin 4) has an active range from -9 V to -2 V. When
V3 = -9 V the phase angle is at its maximum amax, i.e., the current flow angle is minimum. The minimum phase angle amin is set with V3 ³ -1 V.
Automatic Retriggering
The current-detector circuit monitors the state of the triac after triggering by measuring
the voltage drop at the triac gate. A current flow through the triac is recognized when the
voltage drop exceeds a threshold level of typically 40 mV.
If the triac is quenched within the relevant half wave after triggering (for example owing
to low load currents before or after the zero crossing of current wave, or for commutator
motors, owing to brush lifters), the automatic retriggering circuit ensures immediate
retriggering, if necessary with a high repetition rate, tpp/tp, until the triac remains reliably
triggered.
Current Synchronization, Current synchronization fulfils two functions:
Pin 8
• Monitoring the current flow after triggering. In case the triac extinguishes again or it
does not switch on, automatic triggering is activated as long as triggering is
successful.
•
Avoiding triggering due to inductive load. In the case of inductive load operation, the
current synchronization ensures that in the new half wave no pulse is enabled as
long as there is a current available from the previous half wave, which flows from the
opposite polarity to the actual supply voltage.
A special feature of the IC is the realization of current synchronization. The device evaluates the voltage at the pulse output between the gate and reference electrode of the
triac. This results in saving the separate current synchronization input with specified
series resistance.
4
U2008B
4712A–AUTO–05/03
U2008B
Voltage Synchronization
with Mains Voltage
Compensation, Pin 7
The voltage detector synchronizes the reference ramp with the mains supply voltage. At
the same time, the mains-dependent input current at Pin 7 is shaped and rectified internally. This current activates automatic retriggering and at the same time is available at
Pin 3 (see Figure 9). By suitable dimensioning, it is possible to attain the specified compensation effect. Automatic retriggering and mains voltage compensation are not
activated until ½V7 - V4½ increases to 8 V. The resistance Rsync. defines the width of the
zero voltage cross-over pulse, synchronization current, and hence the mains supply
voltage compensation current. If the mains voltage compensation and the automatic
retriggering are not required, both functions can be suppressed by limiting ½V7 - V4½ £ 7
V (see Figure 4).
Figure 4. Suppression of Automatic Retriggering and Mains Voltage Compensation
Mains
R2
7
2x
BZX55
C6V2
U2008B
4
A further feature of the IC is the selection between soft start and load-current compensation. Soft start is possible by connecting a capacitor between Pin 1 and Pin 4 (see
Figure 8). In the case of load-current compensation, Pin 1 is directly connected with
resistance R6, which is used for sensing load current.
Load Current Detection,
Pin 1
The circuit continuously measures the load current as a voltage drop at resistor R6. The
evaluation and use of both half waves results in a quick reaction to load-current change.
Due to voltage at resistor R6, there is an increase of input current at Pin 1. This current
increase controls the internal current source, whose positive current values are available at Pin 3 (see Figure 11). The output current generated at Pin 3 contains the
difference from the load-current detection and the mains-voltage compensation (see
Figure 9).
The effective control voltage is the final current at Pin 3 together with the desired value
network. An increase of mains voltage causes an increase of the control angle a. An
increase of load current results in a decrease of the control angle. This avoids a
decrease in revolution by increasing the load as well as an increase of revolution by the
increment of mains supply voltage.
5
4712A–AUTO–05/03
Absolute Maximum Ratings
VS = 14 V, reference point Pin 4, unless otherwise specified
Parameters
Symbol
Value
Unit
-IS
30
mA
-iS
100
mA
±IsyncV
±isyncV
5
20
mA
mA
Control voltage
-VI
VS to 0
V
Input current
±II
500
mA
-Ijmax
0.5
mA
Input current
II
1
mA
Input voltage
VI
-VS to +2
V
Input voltage Pin 8
+VI
-VI
2
VS
V
V
Storage temperature range
Tstg
-40 to +125
°C
Junction temperature range
Tj
-10 to +125
°C
Symbol
Value
Unit
Current limitation Pin 5
t £ 10 µs
Synchronous currents Pin 7
t £ 10 µs
Phase Control Pin 3
Charge current Pin 6
Load Current Monitoring/Soft Start, Pin 1
Pulse output
Thermal Resistance
Parameters
Junction ambient
6
DIP8
RthJA
110
K/W
SO8 on p.c.
RthJA
220
K/W
So8 on ceramic
RthJA
140
K/W
U2008B
4712A–AUTO–05/03
U2008B
Electrical Characteristics
Parameters
Test Conditions
Symbol
Min.
14.5
14.6
Typ.
Max.
Unit
16.5
16.8
V
V
3.0
mA
11.3
12.3
V
0.15
2
30
mA
µA
8.5
9.0
V
100
µA
2.05
V
Supply (Pin 5)
Supply-voltage limitation
-IS = 3.5 mA
-IS = 30 mA
-VS
-VS
Current requirement
Pins 1, 4 and 7 open
-IS
Voltage Monitoring (Pin 5)
Turn-on threshold
-VTON
Phase Control
Input current
Voltage sync. Pin 7
Current sync. Pin 8
±IsyncV
±IsyncI
3
Voltage limitation
±IL = 2 mA Pin 7
±VsyncV
8.0
Reference Ramp (see Figure 5)
Charge current
Pin 7
Ij
1
Start voltage
Pin 2
-Vmax
1.85
Temperature coefficient of start
voltage
Pin 2
-TCR
Rj - reference voltage
Ij = 10 µA, Pins 6 to 5
VRj
Temperature coefficient
Ij = 10 µA, Pin 6
Ij = 1 µA
1.95
-0.003
0.96
1.02
%/K
1.10
0.03
0.06
TCVRj
TCVRj
V
%/K
%/K
Pulse Output (see Figure 6) (Pin 8)
Output-pulse current
V8 = -1.2, RGT = 0 W
I0
Output-pulse width
C3 = 3.3 nF, VS = Vlimit
tp
100
125
150
30
mA
µs
Automatic Retriggering (Pin 8)
Turn-on threshold voltage
±VION
20
60
mV
I7 ³ 150 µA
tpp
3
5
7.5
tp
Starting current
V1–4 = 8 V
I0
5
10
15
µA
Final current
V1–4 = -2 V
25
40
Repetition rate
Soft Start (see Figure 8) (Pin 1)
Discharge current
Output current
Pin 3
I0
15
-I0
0.5
-I0
0.2
14
µA
mA
2
mA
Mains Voltage Compensation (see Figure 9)
Current transfer gain I7/I3
Pins 7, Pin 3
Pins 1 and 2 open
Gi
Reverse current
V(R6) = V3 = V7 = 0, Pin 3
±IR
17
20
2
µA
Load-current Detection, V7 = 0 (see Figure 11)
Transfer gain
I3/V1
Offset current
V1 = 0, V3 = -8 V,
G
0.28
0.32
0.37
µA/mV
I0
0
3
6
µA
Input voltage
Pin 1
-VI
300
400
mV
Input offset voltage
Pin 1
±V0
6
mV
Pin 3
7
4712A–AUTO–05/03
Figure 5. Ramp Control
Phase Angle a (°)
250
200
33 nF
10 nF 6.8 nF
4.7 nF
3.3 nF
2.2 nF
150
Cj/t = 1.5 nF
100
50
0
0
200
400
600
800
1000
Rj(R8) (kW)
Figure 6. Pulse Output
120
VGT = -1.2 V
100
IGT (mA)
80
60
40
20
0
0
200
400
600
800
1000
RGT (W)
Figure 7. Output Pulse Width
400
Dtp/DCj = 9 ms/nF
tp (ms)
300
200
100
0
0
10
20
30
Cj (nF)
8
U2008B
4712A–AUTO–05/03
U2008B
Figure 8. Option Soft Start
1
C5 = 1 mF
0
V1-4( V )
-1
10 mF
-2
-3
Supply
R1 = 22 kW/2 W
C1 = 100 mF/25 V
4.7 mF
-4
-5
0
1
2
3
4
5
t(s)
Figure 9. Mains Voltage Compensation
0
I3 (mA)
-40
-80
-120
-160
Reference Point
Pin 10
Pins 1
VS = -13 V
-200
-2
-1
0
1
2
I7 (mA)
Figure 10. Maximum Resistance of R1
100
Max. Series Resistance
VM = 230 V
R1max (kW)
80
60
40
20
0
0
2
4
6
8
1
0
IS (mA)
9
4712A–AUTO–05/03
Figure 11. Load-current Detection
200
I5 (mA)
160
V6 = Ref = V8
VS = -13 V
V15 = V10 = 0 V
Reference Point
Pin 8
120
80
40
0
-400
-200
0
200
400
V(R6) (mV)
Figure 12. Power Dissipation of R1
10
Power Dissipation at Series Resistance R1
PV (W)
8
6
4
2
0
0
10
20
30
50
40
R1 (kW)
Figure 13. Power Dissipation of R1 According to Current Consumption
10
Power Dissipation at Series Resistance
PV (W)
8
6
4
2
0
0
3
6
9
12
15
IS (mA)
10
U2008B
4712A–AUTO–05/03
U2008B
Ordering Information
Extended Type Number
Package
U2008B-x
Remarks
DIP8
Tube
U2008B-xFP
SO8
Tube
U2008B-xFPG3
SO8
Taped and reeled
Package Information
Package DIP8
Dimensions in mm
7.77
7.47
9.8
9.5
1.64
1.44
4.8 max
6.4 max
0.5 min 3.3
0.58
0.48
0.36 max
9.8
8.2
2.54
7.62
8
5
technical drawings
according to DIN
specifications
1
4
Package SO8
Dimensions in mm
5.2
4.8
5.00
4.85
3.7
1.4
0.25
0.10
0.4
1.27
6.15
5.85
3.81
8
0.2
3.8
5
technical drawings
according to DIN
specifications
1
4
11
4712A–AUTO–05/03
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© Atmel Corporation 2003.
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Printed on recycled paper.
4712A–AUTO–05/03
xM