PWM Power Control for DC Loads
Description
The U2352B bipolar circuit is a PWM device for controlling logic level Power MOSFETs and IGBTs. It allows
simple power control for dc loads. Integrated load current
monitoring with adjustable switch-off threshold also
gives the option of measuring the load current via the
MOS transistor’s on-state resistance, R
shunt resistor.
U2352B
, or via a
DS(on)
Special Features
D
Pulse width control up to 50 kHz clock frequency
D
Load current monitoring via the on-state resistance,
R
D
100 mA push-pull output stage
D
Voltage monitoring
D
Temperature-compensated supply voltage limitation
D
Chip temperature monitoring
, of the FET or via shunt resistor (optional)
DS(on)
V
2 x I
S
1
1
I
S
Oscillator
Applications
D
Battery-operated screwdrivers
D
Battery-operated machine tools
D
Halogen lamp controllers
D
Dimmers
D
Electronic fuses
D
High-performance clock generators
Package: DIP8, SO8
Chip
temperature
monitoring
140°C
Reference
voltage
Voltage
limitation 6.8 V
8
V
S
2
current measurement
3
4
–
K2
+
Load current
monitoring
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
–
K1
+
Time window
Output stage
logic
Q
Q
S
R
POR
S
2
Figure 1. Block diagram
Push-pull
output stage
7
6
GND
5
95 9670
1 (8)
U2352B
B
V
Load
M
1
1
R
D
voltage
Reference
8
Voltage
2
D
S
V
limitation 6.8 V
1
T
3
D
G
R
7
6
Push-pull
output stage
GND
D
*) R
5
95 9671
* Load current can also optionally be measured via shunt resistor
R
°
Chip
S
V
140 C
monitoring
temperature
Oscillator
logic
Output stage
K1
–
+
Q
S
Q
Time window
–
current measurement
K2
+
POR
monitoring
Load current
2
S
2 (8)
2 x I
5
R
2
R
1
S
1
Osc
C
I
2
Control
V
6
R
8
R
7
R
3
2
C
Set
I
3
R
1
C
4
3
C
9
R
4
R
Figure 2. Block diagram with typical circuit
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
Pin Description
U2352B
Osc
V
Contr
I
Set
S2OUT
1
2
3
4
95 9701
8
7
6
5
V
S
Output
GND
IN
S
2
Supply, Pin 8
Internal voltage limitation in the U2352B allows a simple
supply via a series resistor R
. This enables operation of
1
the circuit under different operating voltages. Supply
voltage between Pin 8 (V
and is smoothed by C1.
R
1
The series resistor R
V
*
V
+
Bmin
I
tot
R
1max
) and Pin 6 (GND) builds up via
S
is calculated as follows:
1
Smax
where
V
= Minimum operating voltage
Bmin
= Maximum supply voltage
V
Smax
I
= I
tot
I
= Maximum current consumption of the IS
Smax
I
X
+ I
Smax
X
= Current consumption of the external elements
Various thresholds are derived from an internal reference
voltage source.
Voltage Monitoring
During build-up and reduction of the operating voltage,
uncontrolled output pulses with excessively low amplitude are suppressed by the internal monitoring circuit. All
latches are reset and the output of the load current detection Pin 4 is switched to ground.
Chip Temperature Monitoring
U2352B has integrated chip temperature monitoring
which switches off the output stage when a temperature
of approximately 140°C is reached. The device is not
enabled again until cooling has taken place and the supply
voltage has been switched off and then back on again.
Pin Symbol Function
1 Osc Oscillator
2 V
3 I
Contr
Set
Control voltage input
Setpoint value current
monitoring
4 S2OUT Output, current switch S
5 S2IN Input, current switch S
2
2
6 GND Ground
7 Output Output
8 V
S
Supply voltage
Pulse Width Control, Pins 1 and 2
At the frequency-determining capacitor, C
switching over of two internal current sources gives rise
to a triangular voltage which comparator, K
with the control voltage at Pin 2. If the voltage, V
more negative than the control voltage V
stage is switched on via the output stage logic. When C
is charged, the whole process then runs in reverse order
(see figure 3).
, at Pin 1,
osc
, compares
1
, the output
2
1
, is
osc
Load Current Monitoring, Pins 3, 4, 5
Load current can be measured with the aid of an external
shunt resistor, but this is only appropriate for decreased
loads due to additional power loss and component size
and costs. This involves the shunt voltage being fed
directly to Pin 4 via a protective resistor (see figure 5).
In order to save component costs and additional power
loss, the integrated load current monitoring allows the
load current to be directly measured via the voltage drop
at the on-state resistance, R
additional shunt resistor. The drain voltage of the FET is
supplied via an external protective resistor to Pin 5.
During the off-state of the FET, a diode clamp circuit
protects the detection input, Pin 5. In the on state, the load
current flowing through the FET generates a
corresponding voltage drop at its R
converted into a current at Pin 5 by the protective resistor.
This current reaches the integration element at Pin 4 via
the switch S
, which is only closed in the on-state of the
2
FET . If the voltage at Pin 4 exceeds the setpoint value set
at Pin 3, as a result of a high load current, the shutdown
latch is set and the output stage is blocked. To enable the
circuit again, it is necessary to switch the operating
voltage off and then back on again.
, of the FET, without an
DS(on)
, which is in turn
DS(on)
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
Switch-off behavior is adjusted with the resistors at Pin 4
and Pin 5 and also with the capacitor at Pin 4.
3 (8)
U2352B
A time space, Dt, must be observed between switching the
output stage off and on and switching S
(current
2
measurement enable switch) in order to avoid incorrect
measurement and incorrect switching-off. To create this
V
0.6
V
V
S
2
V
1
V2*
0.3 V
S
V
7
S
2
closed
open
D
t
time window, the control voltage V
about DV
voltage, V
= approximately 300 mV and the resulting
2
*, is compared with the triangular voltage, V
2
(see figure 3).
95 9672
D
t
t
is reduced internally
2
D
V
2
1
Figure 3. Signal characteristics of pulse width control with time window generation
Absolute Maximum Ratings
Reference point Pin 6, unless otherwise specified
Parameters Symbol Value Unit
Power supply
current Pin 8
t < 10 ms Pin 8
Push-pull output stage
Output current Pin 7
t < 2 ms Pin 7
Input currents Pins 4 and 5
Pins 1 and 3
Input voltages Pins 1, 2 and 3 V
Storage temperature range T
Junction temperature T
Ambient temperature T
Thermal Resistance
Parameters Symbol Maximum Unit
Junction ambient
DIP8
SO8 on PC board
SO8 on ceramic
R
I
i
±I
±i
±I
amb
thJA
I
stg
S
S
O
O
I
I
I
40
400
20
100
10
2
0 to V
8
mA
mA
mA
V
–40 to +125 °C
j
+125 °C
–10 to +100 °C
110
220
K/W
140
4 (8)
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
Electrical Characteristics
U2352B
VS = 6 V, T
= 25_C, reference point Pin 6, unless otherwise specified
amb
Parameters Test Conditions / Pins Symbol Min. Typ. Max. Unit
Supply voltage limitation IS = 5 mA Pin 8
I
= 20 mA
S
Current consumption VS = 6 V Pin 8 I
Voltage monitoring
Switch-on threshold
Switch-off threshold
Oscillator
[
f
OSC
kHz][
55
[nF]
C
OSC
Pin 8
Pin 8
Pin 1
[V]
V
S
Upper threshold (0.6 VS)
Lower threshold (0.3 V
)
S
Charge current
Discharge current
Control voltage input
Input voltage range
Input current,
Offset voltage K
1
Window, current
0 V ≤ V
≤ V8Pin 2
2
Pin 2
Pin 2–1
Pin 2–1
measurement
Load current monitoring
Setpoint value input:
Input voltage range
Input current
Offset voltage K
2
0 V ≤ V
≤ 6 V Pin 3
3
Pin 3
Pin 4–3 ±V
Load current detection:
Voltage limitation
Voltage limitation
I5 = 1 mA Pin 5
I
= –1 mA Pin 5
5
Discharge current at POR Pin 4 I
Switch S
2
Pin 5–4
Residual voltage at closed
switch
V4 = 0 V, I5 = 50 mA
V
= 0.1 V, I5 = 50 mA
4
= 0.3 V, I5 = 50 mA
V
4
V
= 0.3 V, I5 = 100 mA
4
Push-pull output stage Pin 7
Upper saturation voltage I7 = –2 mA Pin 7–8 –V
Lower saturation voltage I7 = 10 mA Pin 7 V
Output current
ON state
OFF state
t ≤ 2 ms
t ≤ 2 ms
V
V
SON
V
SOFF
V
V
–I
I
V
±I
±V
–DV
V
±I
V
–V
V
–i
i
S
Tu
Tl
ch
dis
Offs
Offs
L
dis
Sat
Satu
Satl
o
S
6.4
6.5
6.8
6.9
7.2
7.3
V
2.7 3.5 mA
5.2
4.7
3.4
1.7
26
26
I
i
2
I
i
0
260
0 6
5.6
5.1
3.6
1.8
33
33
300
6.0
5.5
3.8
1.9
40
40
V
500
15
340
500
V
V
V
m
A
m
A
8
V
nA
mV
mV
V
nA
15 mV
2.3
L
0.7
V
1 mA
175
mV
150
125
200
1 V
0.3 V
o
100
mA
100
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
5 (8)
U2352B
RD = 20 k
95 9673
1000
V
W
5
S
2
4
R
9
V
OUT
IN
800
600
OUT
V ( mV )
400
200
0
0 200 400 600 800
95 9686
VIN ( mV )
R9=1M
W
Figure 4. Typical circuitry of the current switch S2 with associated transfer characteristics (S2 closed)
R
1
R
2
82 k
R
W
5
33 k
W
D1, T1 and R
are
sh
D
1
M
load dependent
500K
100K
50K
20K
10K
5K
1000
Load
W
W
W
W
W
W
V
B
C
4.7 mF
10 k
R
1k
C
osc
1
8
680 pF
Speed
R
R
47 k
3
6
W
1
R
7
27 k
68 k
W
W
2
R
8
C
2
U2352B
7
470 nF
D
2
D
3
T
1
R
G
W
Torque
C
4
3
4
4
W
C
3
R
1.5 k
9
W
10 nF
95 9674
6
5
R
sh
GND
6 (8)
Figure 5. Speed control with load current monitoring (load current detection via shunt resistor)
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
Dimensions in mm
Package: DIP8
U2352B
94 8873
Package: SO8
94 8862
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
7 (8)
U2352B
Ozone Depleting Substances Policy Statement
It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to
1. Meet all present and future national and international statutory requirements.
2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems
with respect to their impact on the health and safety of our employees and the public, as well as their impact on
the environment.
It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as
ozone depleting substances (ODSs).
The Montreal Protocol ( 1987) and its London Amendments (1990) intend to severely restrict the use of ODSs and
forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban
on these substances.
TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of
continuous improvements to eliminate the use of ODSs listed in the following documents.
1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively
2. Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental
Protection Agency (EPA) in the USA
3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C (transitional substances) respectively.
TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain
such substances.
We reserve the right to make changes to improve technical design and may do so without further notice.
Parameters can vary in different applications. All operating parameters must be validated for each customer
application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized
application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of,
directly or indirectly, any claim of personal damage, injury or death associated with such unintended or
unauthorized use.
8 (8)
TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany
Telephone: 49 (0)7131 67 2831, Fax number: 49 (0)7131 67 2423
TELEFUNKEN Semiconductors
Rev . A1, 29-May-96
Loading...