U2008B
Low-Cost Phase-Control IC with Soft Start
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.
Features
Full wave current sensing |
|
Internal supply-voltage monitoring |
Mains supply variation compensated |
|
Current requirement 3 mA |
Variable soft-start or load-current sensing |
Applications |
|
Voltage and current synchronization |
||
Automatic retriggering switchable |
|
Low-cost motor control |
Triggering pulse typ. 125 mA |
|
Domestic appliance |
Block Diagram
|
|
|
|
|
22 k /2W |
|
BYT51K |
|
|
|
|
|
230 V ~ |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
R2 |
R1 |
D1 |
R8 |
|
|
|
|
|
|
|
|
|
max |
|
|
|
|
|
|||
|
|
|
|
330 k |
1 M |
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
|
|||
|
Load |
|
|
|
7 |
|
6 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||
|
|
|
Limiting |
Voltage |
|
|
|
Mains voltage |
|
|
|
|
|
|
|
detector |
detector |
|
|
|
compensation |
|
|
|
|
|
|
|
Automatic |
|
|
|
|
|
|
|
|
|
|
|
|
retriggering |
|
|
|
|
|
U2008B |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Phase |
|
|
|
|
5 |
±VS |
|
|
|
|
Current |
control unit |
|
|
|
|
|
|||
|
TIC |
|
|
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
|
|
||
|
|
detector |
|
ö = f (V3) |
|
|
|
|
|
|
C1 |
|
|
226 |
|
|
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
|
|
|
22 mF/ |
|
|
R3 |
|
|
|
|
|
|
|
|
|
|
|
|
8 |
|
|
|
|
|
|
Supply |
|
|
25 V |
|
|
|
|
|
|
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
voltage |
4 |
GND |
|
|
180 |
|
|
|
|
|
|
|
limiting |
|
||
|
|
|
Full wave load |
|
|
|
+ |
± |
Reference |
|
|
|
|
|
|
|
|
|
voltage |
|
|
|
|||
|
|
1 |
|
|
|
|
|
|
|
|||
|
|
current detector |
|
|
|
|
|
|
|
|
|
|
|
|
|
Soft start |
|
|
|
|
|
Voltage |
|
|
R14 |
|
|
|
|
|
|
|
|
monitoring |
|
|
||
|
|
|
|
|
|
|
|
|
|
47 k |
||
|
|
|
|
|
2 |
3 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||
|
|
|
|
|
|
|
R10 |
|
100 k |
Set point |
P1 |
|
|
|
|
|
|
|
|
|
|
|
|||
R6 |
^ |
|
|
|
|
|
|
|
|
|
|
|
|
V(R6) = ±250 mV |
|
C3 |
C4 |
|
Load current |
|
R7 |
|
|||
|
|
|
|
3.3 nF |
100 nF |
|
compensation |
|
|
|
||
|
|
|
|
|
|
|
|
|
|
|
||
Figure 1. Block diagram with typical circuit: Load current sensing
Rev. A4, 12-Jan-01 |
1 (10) |
U2008B
Ordering Information
Extended Type Number |
Package |
Remarks |
U2008B-x |
DIP8 |
Tube |
U2008B-xFP |
SO8 |
Tube |
U2008B-xFPG3 |
SO8 |
Taped and reeled |
230 V ~ |
|
|
|
22 k /2W |
BYT51K |
|
|
|
|
|
|
L |
|
|
R2 |
R1 |
D1 |
R8 |
|
|
|
|
|
|
|
|
|
max |
|
|
|
|
|
||
|
|
|
680 k |
|
|
470 k |
|
|
|
||
Load |
|
|
|
7 |
|
6 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
||
|
|
Limiting |
Voltage |
|
|
|
Mains voltage |
|
|
|
|
|
|
detector |
detector |
|
|
|
compensation |
|
|
|
|
|
|
Automatic |
|
|
|
|
|
|
|
|
|
|
|
retriggering |
|
|
|
|
|
U2008B |
|
|
|
|
|
|
|
Phase |
|
|
|
|
5 |
±VS |
|
|
|
|
control unit |
|
|
|
|
|
|||
TIC |
|
Current |
|
|
|
|
|
|
|
||
|
detector |
|
ö = f (V3) |
|
|
|
|
|
C1 |
||
226 |
|
|
|
|
|
|
|
||||
|
|
|
|
|
|
|
|
|
|
||
R3 |
|
|
|
|
|
|
|
Supply |
|
|
100 mF/ |
8 |
|
|
|
|
|
|
|
|
25 V |
||
|
|
|
|
|
|
|
|
|
|||
|
|
|
|
|
|
|
|
voltage |
|
GND |
|
180 |
|
|
|
|
|
|
|
limiting |
4 |
|
|
|
|
Full wave load |
|
|
|
+ |
± |
Reference |
|
|
|
|
|
|
|
|
voltage |
|
|
|
|||
|
1 |
|
|
|
|
|
|
|
|||
|
current detector |
|
|
|
|
|
|
|
|
|
|
|
|
Soft start |
|
|
|
|
|
Voltage |
|
|
|
|
|
|
|
|
|
|
monitoring |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2 |
3 |
|
|
|
|
|
|
|
|
|
|
|
|
R10 |
|
68 k |
Set point |
P1 |
|
C5 |
Soft start |
|
|
|
|
|
50 k |
||||
C3 |
C4 |
|
|
|
|
|
|
||||
|
4.7mF/ |
25 V |
|
|
|
|
|
R7 |
|
||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10 nF |
100 nF |
|
|
|
|
220 k |
|
|
N |
|
|
|
|
|
|
|
|
|
|
|
Figure 2. Block diagram with typical circuit: Soft start
2 (10) |
Rev. A4, 12-Jan-01 |
U2008B
Pin Description
Isense |
|
|
|
Output |
1 |
|
8 |
||
Cϕ |
|
|
|
Vsync. |
2 |
|
7 |
||
|
|
U2008B |
|
Rϕ |
Control |
|
|
|
|
3 |
|
6 |
||
GND |
|
|
|
VS |
|
|
|
||
4 |
|
5 |
||
|
|
|
|
|
|
|
|
|
|
Figure 3. Pinning
Mains Supply, Pin 5, Figure 2
The integrated circuit U2008B, which also contains voltage limiting, can be connected via D1 and R1 via the mains supply. Supply voltage between Pin 4 (pos., ) and Pin 5 is smoothed by C1.
Series resistance R1 can be calculated as follows:
|
|
VM ± VSmax |
||
|
R1max 0.85 x |
|
|
|
|
2 x Itot |
|||
|
|
|
||
where: |
|
|
|
|
VM |
Mains voltage |
|||
VSmax |
Maximum supply voltage |
|||
Itot |
ISmax Ix = Total current compensation |
|||
ISmax |
= |
Maximum current consumption of the IC |
||
Ix |
= |
Current consumption of the external |
||
|
|
components |
||
An operation with external stabilized DC voltage is not recommended.
Voltage Monitoring
When the voltage is built up, uncontrolled output pulses are avoided by internal voltage monitoring. Apart from that, all latches in the circuit (phase control, load limit regulation) are reset and the soft-start capacitor is short circuited. This guarantees a specified start-up 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.
Pin |
Symbol |
Function |
1 |
Isense |
Load current sensing |
2 |
Cϕ |
Ramp voltage |
3 |
Control |
Control input / compensation |
|
|
output |
4 |
GND |
Ground |
5 |
±VS |
Supply voltage |
6 |
Rϕ |
Ramp current adjustment |
7 |
Vsync. |
Voltage synchronization |
8 |
Output |
Trigger output |
Phase Control, Pin 6
The function of the phase control is largely 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 C and its charging current I ö.
The charging current can be regulated, changed, altered
using R at Pin 6. The maximum phase angle, αmax, (minimum current flow angle ömin) can also be adjusted
by using R (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 C (tp = 9 ms/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,
then the phase angle is at its maximum αmax, i.e., the current flow angle is minimum. The minimum phase
angle αmin is set with V3 ±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 typ. 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.
Rev. A4, 12-Jan-01 |
3 (10) |
Loading...