Datasheet U6081B Datasheet (TEMIC)

U6081B

PWM Power Control with Low Duty Cycle Switch Off

Description

U6081B is a PWM IC in bipolar technology for the control of an N-channel power MOSFET used as a high side switch. The IC is ideal for the use in the brightness

Features

D

Pulse width modulation up to 2 kHz clock frequency

D

Protection against short circuit, load dump overvoltage and reverse V

D

Duty cycle 0 to 100%

D

Output stage for power MOSFET

S

Ordering Information

Extended Type Number Package Remarks

U6081B DIP8

control (dimming) of lamps e.g., in dashboard applications.

D

Interference and damage protection according to VDE 0839 and ISO/TR 7637/1.

D

Ground wire breakage protection

D

Charge pump noise suppressed

Block Diagram

C

1

47 k

C

2

V

C

V

S

1

Current monitoring

+ short circuit detection

RC oscillator

4

W

Control input

3

Duty cycle

range

0/13 to 100 %

2

150

R

W

PWM Logic

Voltage

monitoring

3

5

6

Charge

pump

Output

7

8

95 9752

R

Batt

sh

C

3

47 nF

Ground

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

Figure 1. Block diagram with external circuit

1 (8)

U6081B

Pin Description

Batt

8

7

6

5

Output

2 V

Sense

Delay

Batt

S

< 18.5 V

< 23 V.

V

1

S

GND

V

Osc

2

I

3

4

95 9944

Functional Description

Pin 1, Supply Voltage, Vs or V

Overvoltage Detection

Stage 1: If V switched off and switched on again at V (hysteresis).

Stage 2: If V (load-dump protection). At the same time the voltage limitation of the IC is reduced from V This leads to a hysteresis characteristic so that the loaddump detection is switched off again only at V In this case the short–circuit protection is not in operation.

Undervoltage Detection

> 20 V occurs the external transistor will be

Batt

> 28 V, the external transistor is switched on again

Batt

≈ 26 V to VS ≈ 20 V.

S

Pin Symbol Function

1 V

Supply voltage V

S

2 GND IC ground 3 V

Control input (duty cycle)

I

4 Osc Oscillator 5 Delay Short circuit protection delay 6 Sense Current sensing 7 2 V

Voltage doubler

S

8 Output Output

(see figure 2). Pin 3 is protected against short-circuit

R

2

to V

and ground GND (V

Batt

x

16.5 V).

Output Slope Control

The rise and fall time (t

, tf) of the lamp voltage can be

r

limited to reduce radio interference. This is done with an integrator which controls a power MOSFET as source follower. The slope time is controlled by an external capacitor C4 and the oscillator current (see figure 2).

Calculation:

C

+

t

f

With V

tr+

V

Batt

= 12 V, C4 = 470 pF and I

Batt

4

I

osc

= 40 mA, we thus

osc

obtain a controlled slope of

+

tr+

t

f

12 V

470 pF

40mA

+

141ms

In the event of voltages of approximately V

Batt

< 5.0 V, the external FET is switched off and the latch for shortcircuit detection is reset.

A hysteresis ensures that the FET is switched on again at approximately V

 5.4 V.

Batt

Pin 2, GND

Ground-Wire Breakage

To protect the FET in the case of ground-wire breakage, a 820-kW resistor between gate and source is recommended to provide proper switch-off conditions.

Pin 3, Control Input

The pulse width is controlled by means of an external potentiometer (47 kW). The characteristic (angle of rotation/duty cycle) is linear. The duty cycle can be varied from 0 to 100%. To avoid inadmissibly high filament cold currents, the dimmer is switched off at duty cycles of approximately < 10% or is switched on only at duty cycles of approximately > 13% (hysteresis). It is possible to further restrict the duty cycle with the resistors R

2 (8)

and

1

A 100-W resistor in series to C4 is recomended to damp device oscillations (see figure 2).

Pin 4, Oscillator

The oscillator determines the frequency of the output

. It is

2

a

1

a

2

a

3

voltage. This is defined by an external capacitor, C charged with a constant current, I, until the upper switching threshold is reached. A second current source is then activated which taps a double current, 2 I, from the charging current. The capacitor, C

, is thus discharged

2

by the current, I, until the lower switching threshold is reached. The second source is then switched off again and the procedure starts again.

Example for oscillator frequency calculation:

IS

)

R

3

)

R

3

)

R

3

V

T100

V

T¦100

VTL+

+

VS

a1+(V

a2+(V

a3+(V

Batt

*

IS

*

IS

where

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

+

V

VTL+

a1,

High switching threshold (100% duty cycle)

T100

+

Tt100

High switching threshold(t100% duty cycle)

Low switching threshold

a2 and

a3 are fixed constant.

The above mentioned threshold voltages are calculated for the following values given in the data sheet.

= 12 V, IS = 4 mA, R3 = 150 W ,

V

Batt

= 0.7,

a

1

V

VTL+

a2 = 0.67 and

+(12 V*4mA 150

T100

+

Tt100

11.4 V 0.67+7.6 V

11.4 V 0.28+3.2 V

a3 = 0.28.

W)

0.7[8V

For a duty cycle of 100%, an oscillator frequency, f, is as follows:

U6081B

Pins 5 and 6, Short-Circuit Protection and Current Sensing

1. Short-Circuit Detection and Time Delay, t

The lamp current is monitored by means of an external shunt resistor. If the lamp current exceeds the threshold for the short-circuit detection circuit (V

T2

duty cycle is switched over to 100% and the capacitor C is charged by a current source of 20 m A (Ich – I external FET is switched off after the cut-off threshold

) is reached. Renewed switching on the FET is

(V

T5

possible only after a power-on reset. The current source,

ensures that the capacitor C5 is not charged by

I

dis,

parasitic currents. The capacitor C

is discharged by I

5

to typ. 0.7 V. Time delay, t t

+

C5@(VT5*

d

, is as follows:

d

0.7 V)ń(Ich*

)

I

dis

With C5 = 330 nF and VT5 = 9.8 V, (Ich – I we have

t

+

d

+

150 ms.

330 nF

@(9.8 V*0.7 V)ń20m

A

d

 90 mV), the

). The

dis

) = 20 mA,

dis

5

I

f

+

2

(V

T100

*

osc

)

V

TL

,whereasC2+

C

2

and I

+40m

osc

22 nF

A

Therefore:

f

+

2

(8V*3.2 V)

40mA

22 nF

+

189 Hz

For a duty cycle of less than 100%, the oscillator frequency , f, is as follows:

I

f

+

2

(V

Tt100

*

osc

)

V

C

TL

)4

2

V

C

Batt

4

whereas C4 = 470 pF

40

m

f

+

2

(7.6 V*3.2 V)

+

185 Hz

A

22 nF)4 12 V 470 pF

A selection of different values of C2 and C4, provides a range of oscillator frequency, f, from 10 to 2000 Hz.

2. Current Limitation

The lamp current is limited by a control amplifier to protect the external power transistor. The voltage drop across an external shunt resistor acts as the measured variable. Current limitation takes place for a voltage drop of

[100 mV. Owing to the difference

V

T1

V

T1–VT2

10 mV it is ensured that current limitation

[

occurs only when the short circuit detection circuit has responded.

After a power-on reset, the output is inactive for an half oscillator cycle. During this time, the supply voltage capacitor can be charged so that the current limitation is guaranteed in the event of a short circuit when the IC is switched on for the first time.

Pins 7 and 8, Charge Pump and Output

Output, Pin 8, is suitable for controlling a power MOSFET . During the active integration phase, the supply current of the operational amplifier is mainly supplied by the capacitor C charge is generated by an integrated oscillator



400 kHz) and a voltage doubler circuit. This

(f

7

permits a gate voltage supply at a duty cycle of 100%.

(bootstrapping). Additionally, a trickle

3

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

3 (8)

U6081B

T2 S 6

g

Absolute Maximum Ratings

Parameters Symbol Value Unit Junction temperature T Ambient temperature range T Storage temperature range T

j

amb

stg

Thermal Resistance

Parameters Symbol Maximum Unit Junction ambient R

thJA

Electrical Characteristics

T

= –40 to +110°C, V

amb

ground, unless otherwise specified (see figure 1). All other values refer to Pin GND (Pin 2).

Parameters Test Conditions / Pins Symbol Min Typ Max Unit Current consumption Pin 1 I Supply voltage Overvoltage detection,

Stabilized voltage IS = 10 mA Pin 1 V Battery undervoltage

detection Battery overvoltage detection Pin 2 Stage 1: – on

Stage 2: – on

Stabilized voltage IS = 30 mA Pin 1 V Short-circuit protection Pin 6 Short-circuit current

limitation Short-circuit detection VT2 = VS – V

Delay timer short-circuit detection, V Switched off threshold VT5 = VS – V Charge current I Discharge current I Capacitance current I5 = Ich – I

Voltage doubler Pin 7

Voltage Duty cycle 100% V Oscillator frequency f Internal voltage limitation I7 = 5 mA V

= 9 to 16.5 V, (basic function is guaranteed between 6.0 V to 9.0 V) reference point is

Batt

S

V

Batt

stage 1

24.5 27.0 V

4.4

4.8

18.3

16.7

25.5

19.5

18.5 20.0 21.5 V

85 100 120 mV

75 90 105 mV

T2

3 10 30 mV

9.5 9.8 10.1 V

13 20 27 mA

2 V

S

280 400 520 kHz

26 27.5 30.0 V

V

S+14

ON

V

OFF

V

– off

V

– off

VT1 = VS – V

6

V

VT1 – V

= 12 V Pin 5

Batt

5

dis

V

(whichever is lower) V

Batt

T1

T2

T5

ch

dis

I

5

7

Z

7

7 7

150 °C –40 to +110 °C –55 to +125 °C

120 K/W

5.0

5.4

20.0

18.5

28.5

23.0

23

3

V

S+15

6.8 mA 25 V

5.6

6.0

21.7

20.3

32.5

26.5

V

S+16

V

m

A

m

A

V

4 (8)

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

U6081B

g

8

Upper

Parameters Test Conditions / Pins Symbol Min Typ Max Unit

Switch-off at small duty cycles V Output disabled V3/V Output active V3/V Hysteresis switch-on Gate output Pin 8 Voltage Low level V

V T

High level, duty cycle 100%

Current V8 = Low level I

V8 = High level, I7 > | I8 |

Oscillator

Frequency Pin4 f 10 2000 Hz Threshold cycle

V8+

Lower

a3+

Oscillator current V Frequency tolerance C4 open, C2 = 470 nF,

duty cycle = 50%

= 12 V Pin 3

Batt

= 16.5 V,

Batt

= 110°C, R3 = 150

amb

High,

a1+

Low,

a2+

V

TL

V

S

= 12 V

Batt

V

T100

V

S

Tt100

V

S

0.3 0.32 0.34

0.32 0.34 0.36

0.004 0.032

0.35 0.70 0.95 V

D

V3/V

8

S S

S

1.5 *)

W

V

8

1.0 mA

V

7

–1.0



a

1

a

2

a

3

I

osc

0.68 0.7 0.72

0.65 0.67 0.69

0.26 0.28 0.3

34 45 54

m

f 6.0 9.9 13.5 Hz

A

*) Reference point is battery ground

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

5 (8)

U6081B

Package Information

Package DIP8

Dimensions in mm

9.8

9.5

1.64

1.44

4.8 max

0.5 min

0.58

0.48

85

14

2.54

7.62

3.3

technical drawings according to DIN specifications

7.77

7.47

6.4 max

0.36 max

9.8

8.2

13021

6 (8)

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

Application

U6081B

Batt

V

330 nF

47 nF

sh

R

4

C

470 pF

6

90 mV

S

V

S

V

1

S

V

5

–

+

ch

I

10 mV

Current limiting

V

+

S

doubler

Voltage

dis

I

3

C

W

820 k

7

Overvoltage

8

–

stage 2

monitoring

+

2

Load

L

R

3

R

W

150

Ground

5

C

W

100

S

V

S

V

S

V

–

+

Reset

–

+

–

+

I

Oscillator

4

1

C

–

+

R

m

47 F

1

Reset

2

C

delay

Switch – on

2 I

W

47 k

22 nF

Reset

Duty factor = 10%

–

+

W

30 k

3

stage 1

monitoring

Overvoltage

S

V

2

R

monitoring

Low voltage

S

V

95 9759

TELEFUNKEN Semiconductors

Rev . A1, 14-Feb-97

Figure 2.

7 (8)

U6081B

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, 14-Feb-97