U6084B PWM Power Control with Automatic Duty Cycle Reduction Description The U6084B is a bipolar technology PWM-IC designed for the control of an N-channel power MOSFET used as a high-side switch. The IC is ideal for use in the brightness control (dimming) of lamps such as, in dashboard applications. For a constant brightness the preselected duty cycle can be reduced automatically as a function of the supply voltage. Features D Interference and damage protection according to D Pulse width modulation up to 2 kHz clock frequency D Protection against short circuit, load-dump VDE 0839 and ISO/TR 7637/1. overvoltage and reverse VS D Charge pump noise suppressed D Duty cycle 0 to 100 % continuously D Output stage for power MOSFET D Ground wire breakage protection Ordering Information Extended Type Number U6084B–FP Package SO16 Remarks Block Diagram VBatt C5 VS 16 Rsh 11 9 Short circuit latch monitoring Current monitoring + short circuit detection 12 5 6 C1 Charge pump RC oscillator C3 47 nF PWM Logic 47 kW 3 C2 13 Control input Duty cycle range 0–100% Output Duty cycle reduction Voltage monitoring 4 1 14 Enable/ disable 2 95 9751 C6 150W R3 Ground Figure 1. Block diagram with external circuit TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 1 (8) U6084B Pin Description GND 1 16 VS En / Dis 2 15 NC VI 3 14 Output Reduct 4 13 2 VS Attenuation 5 12 Sense Osc 6 11 Delay NC 7 10 NC NC 8 9 Latch Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Symbol GND En / Dis VI Reduct NC Osc NC NC Latch NC Delay Sense 2VS Output NC VS Function IC ground Enable/disable Control input (duty cycle) Duty cycle reduction Attenuation Oscillator Not connected Not connected Status short circuit latch Not connected Short circuit protection delay Current sensing Voltage doubler Output Not connected Supply voltage VS 95 9754 Functional Description Pin 4, Duty Cycle Reduction With Pin 4 connected according to figure 2, the set duty 12.5 V. This causes a cycle is reduced as from VBatt power reduction in the FET and in the lamps. In addition, the brightness of the lamps is largely independent of the supply voltage range, VBatt = 12.5 to 16 V. Pin1, GND Ground-Wire Breakage To protect the FET in the case of ground-wire breakage, a 820 kW resistor between gate and source it is recommended to provide proper switch-off conditions. Pin 2, Enable/Disable The dimmer can be switched on or off with pin 2 independently of the set duty cycle. Output Slope Control The rise and fall time (tr, tf) of the lamp voltage can be 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: tf + t +V Pin 3, Control Input tf + t + 12 V 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%. It is possible to further restrict the duty cycle with the resistors R1 and R2 (see figure 2). Pin 3 is protected against short-circuit to VBatt and ground GND (VBatt 16.5 V). Pin 5, Attenuation V2 Approx. >0.7 V or open < 0.7 V or connected to Pin 1 x 2 (8) Function Disable Enable C4 I osc With VBatt = 12 V, C4 = 470 pF and Iosc = 40 m A,we thus obtain a controlled slope of r r Batt 470 pF 40 mA + 141 m s Capacitor C4 connected to Pin 5 damps oscillation tendencies. Pin 6, Oscillator The oscillator determines the frequency of the output voltage. This is defined by an external capacitor, C2. It is TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 U6084B 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, C2, is thus discharged by the current, I, until the lower switching threshold is reached. The second source is then switched off again and the procedure starts once more. A selection of different values of C2 and C4, provides a range of oscillator frequency, f, from 10 to 2000 Hz. Pins 7, 8, 10 and 15 Not connected. Example for Oscillator Frequency Calculation +V V¦ + V V + V V T100 T 100 TL S + (V * I a + (V * I a + (V * I a S S 1 Batt 2 Batt 3 Batt a R 3) S a R 3) S a R 3) S Pin 9, Status Short Circuit Latch 1 2 3 The status of the short-circuit latch can be monitored via Pin 9 (open collector output). where V T100 + High switching threshold (100% duty cycle) V Tt100 V TL Pin 9 L H + High switching threshold (t 100% duty cycle) + Low switching threshold Function Short-circuit detected No short-circuit detected a1, a2 and a3 are fixed constant. Pins 11 and 12, Short-Circuit Protection and Current Sensing The above mentioned threshold voltages are calculated for the following values given in the data sheet. 1. Short-Circuit Detection and Time Delay, td VBatt = 12 V, IS = 4 mA, R3 = 150 W , a1 = 0.7, a2 = 0.67 and a3 = 0.28. + * 4 mA 150 W V t + 11.4 V 0.67 + 7.6 V V + 11.4 V 0.28 + 3.2 V V T100 ) (12 V 0.7 [8 V T 100 TL For a duty cycle of 100%, an oscillator frequency, f, is as follows: f +2 I osc (V T100 Therefore: f +2 *V ) TL C2 + * 3.2 V) Time delay, td, is as follows: 40 mA (8 V + , where C 2 22 nF 40 mA and I osc 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 (VT2 90 mV), the duty cycle is switched over to 100% and the capacitor C5 is charged by a current source of 20 m A (Ich – Idis). The external FET is switched off after the cut-off threshold (VT11) is reached. Renewed switching on the FET is possible only after a power-on reset. The current source, Idis, ensures that the capacitor C5 is not charged by parasitic currents. The capacitor C5 is discharged by Idis to typ. 0.7 V. 22 nF + 189 Hz td + C @ (V * 0.7 V)ń(I * I 5 T11 ch dis ) For a duty cycle of less than 100%, the oscillator frequency, f, is as follows: f +2 (V Tt100 whereas *V TL) C4 = 470 pF + 2 ǒ7.6 V * 3.2 VǓ + 185 Hz I osc C2 m )4 40 A 22 nF With C5 = 330 nF and VBatt = 12 V, we have V Batt C4 td )4 TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 12 V 470 pF + 330 nF @ (9.8 V * 0.7 V)ń20 mA + 150 ms. 3 (8) U6084B 2. Current Limitation Pin 16, Supply Voltage, Vs or VBatt Undervoltage Detection: The lamp current is limited by a control amplifier that protects 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 Owing to the difference VT1 100 mV. VT1–VT2 10 mV, current limitation occurs only when the short-circuit detection circuit has responded. After a power-on reset, the output is inactive for half an oscillator cycle. During this time , the supply voltage capacitor can be charged so that current limitation is guaranteed in the event of a short circuit when the IC is switched on for the first time. In the event of voltages of approx. VBatt < 5.0 V, the external FET is switched off and the latch for short-circuit detection is reset. A hysteresis ensures that the FET is switched on again at approximately VBatt 5.4 V. Overvoltage Detection Stage 1 If overvoltages VBatt > 20 V (typ.) occur, the external transistor is switched off and switched on again at VBatt < 18.5 V (hysteresis). Stage 2 Pins 13 and 14, Charge Pump and Output Output, Pin 14, 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 C3 (bootstrapping). Additionally, a trickle charge is generated by an integrated oscillator (f13 400 kHz) and a voltage doubler circuit. This permits a gate voltage supply at a duty cycle of 100%. If VBatt > 28.5 V (typ.), the voltage limitation of the IC is reduced from 26 V to 20 V. The gate of the external transistor remains at the potential of the IC ground, thus producing voltage sharing between FET and lamps in the event of overvoltage pulses occuring (e.g., load-dump). The short-circuit protection is not in operation. At VBatt < 23 V, the overvoltage detection stage 2 is switched off. Absolute Maximum Ratings Parameters Junction temperature Ambient temperature range Storage temperature range Symbol Tj Tamb Tstg Value 150 –40 to +110 –55 to +125 Unit °C °C °C Symbol RthJA Value 120 Unit K/W Thermal Resistance Parameters Junction ambient Electrical Characteristics Tamb = –40 to +110°C, VBatt = 9 to 16.5 V, (basic function is guaranteed between 6.0 V to 9.0 V) reference point ground, unless otherwise specified (see figure 1). All other values refer to Pin GND (Pin 1). Parameters Current consumption Supply voltage Stabilized voltage Battery undervoltage detection 4 (8) Test Conditions / Pins Pin 16 Overvoltage detection, stage 1 IS = 10 mA Pin 16 – on – off Symbol IS VBatt Min. Typ. VS VBatt 24.5 4.4 4.8 5.0 5.4 Max. 6.8 25 Unit mA V 27.0 5.6 6.0 V V TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 U6084B Parameters Test Conditions / Pins Battery overvoltage detection Pin 2 Stage 1: – on – off Stage 2: – on – off Stabilized voltage IS = 30 mA Pin 16 Short-circuit protection Pin 12 Short-circuit current limita- VT1 = VS – V12 tion Short-circuit detection VT2 = VS – V12 Symbol Min. Typ. Max. Unit VBatt 20.0 18.5 28.5 23.0 20.0 21.7 20.3 32.5 26.5 21.5 V VZ 18.3 16.7 25.5 19.5 18.5 VT1 85 100 120 mV VT2 75 3 90 10 105 30 mV mV 9.5 9.8 23 3 20 10.1 27 mA 150 350 mV VBatt VT1 – VT2 Delay timer short circuit detection Pin 11 Switched off threshold VT11 = VS – V11 Charge current Dicharge current Capacitance current I5 = Ich – Idis Output short-circuit latch Pin 9 Saturation voltage I9 = 100 mA Voltage doubler Pin 13 Voltage Duty cycle 100% Oscillator frequency Internal voltage I13 = 5 mA g limitation (whichever is lower) Gate output Pin 14 Voltage g Low level VBatt = 16.5 V, Tamb = 110 °C, R3 = 150 W High level, duty cycle 100% Current V14 = Low level VT11 Ich Idis I5 Vsat 400 27.5 (VS+15) 520 30.0 (VS+16) kHz V V14 0.35 0.70 0.95 1.5 *) V V14 V 14 Lower Oscillator current Frequency tolerance *) V13 I14 1.0 –1.0 mA I2 –20 –40 –60 mA V4 6.9 7.4 8.0 V f a1 10 0.68 Hz 0.7 2000 0.72 a2 0.65 0.67 0.69 a3 0.26 0.28 0.3 26 6.0 40 9.9 54 13.5 Pin 4 I4 = 500 mA V 14 a + High, a + + Low, a + + VV 1 2 Pin6 V T100 VS V Tt100 VS TL 3 V mA mA 2 VS 280 26 (VS+14) Pin 2 V2 = 0 V V V13 f13 V13 V13 V14 = High level, I13 > | I14 | Enable/ Disable Current Duty cycle reduction Z-voltage Oscillator Frequency Threshold cycle Upper 13 V S VBatt = 12 V C4 open, C2 = 470 nF, duty cycle = 50% Iosc f mA Hz Reference point is battery ground. TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 5 (8) 6 (8) 95 9757 22 nF 47 m F C1 R2 C2 C6 47 kW R1 I 30 k W VS VS 4 3 6 100 W 5 Reset Low voltage monitoring + – + – Reset Switch – on delay Overvoltage monitoring stage 1 2I Oscillator VS VS 2 Reset – + VS VS C5 Idis 11 150 W Ich VS 330 nF VS 9 Ground R3 1 + 8 NC 7 NC 15 14 13 12 10 mV 90 mV VS VS Voltage doubler 10 NC – Current limiting NC Overvoltage monitoring stage 2 16 820 kW C4 47 pF 47 nF Load RL C3 Rsh VBatt U6084B Application Figure 2. TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 U6084B Dimensions in mm Package SO16 Dimensions in mm 5.2 4.8 10.0 9.85 3.7 1.4 0.25 0.10 0.4 1.27 6.15 5.85 8.89 16 0.2 3.8 9 technical drawings according to DIN specifications 1 TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97 13036 8 7 (8) U6084B 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. 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 8 (8) TELEFUNKEN Semiconductors Rev. A1, 14-Feb-97