U6084B

U6084B ATMEL | Alldatasheet

Document overview

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Technical content

Features

 Pulse-width Modulation up to 2 kHz Clock Frequency  Protection against Short-circuit, Load-dump Overvoltage and Reverse VS  Duty-cycle 0 to 100% Continuously  Output Stage for Power MOSFET  Interference and Damage Protection According to VDE 0839 and ISO/TR 7637/1  Charge-pump Noise Suppressed  Ground-wire Breakage Protection

Description

The U6084B is a PWM-IC with bipolar technology 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 constant brightness, the preselected duty-cycle can be reduced automatically as a function of the supply voltage. Figure 1. Block Diagram with External Circuit

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Figure 2. Pinning

1 GND IC ground

2 EN/DIS Enable/disable

3 VI Control input (duty cycle)

4 REDUCT Duty cycle reduction

5 NC Attenuation

7 NC Not connected

8 NC Not connected

9 LATCH Status short-circuit latch

10 NC Not connected

11 DELAY Short-circuit protection delay

12 SENSE Current sensing

14 OUTPUT Output

15 NC Not connected

16 VS Supply voltage V

and source 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. Pin 3 is protected against short-circuit to VBatt and ground GND (VBatt ≤16.5 V). rent (see Figure 3 on page 8). Pin 5 – Attenuation Capacitor C4 connected to pin 5 damps oscillation tendencies. switched off again and the procedure starts once more. Table 1. Pin 2 Function

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Pins 7, 8, 10 and 15 Not connected. The status of the short-circuit latch can be monitored via pin 9 (open collector output). Table 2. Pin 9 Function

4677B–AUTO–02/04 Pins 11 and 12 – Short-circuit Protection and Current Sensing Short-circuit Detection and Time Delay td 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 ≈ 90 mV), the duty cycle is switched over to 100% and capacitor C 5 is charged by a current source of 20 µA (Ich -I dis). The external FET is switched off after the cut-off threshold (V T11) is reached. Renewed switching on the FET is possible only after a power-on reset. The current source, I dis, ensures that capacitor C5 is not charged by parasitic currents. Capacitor C 5 is discharged by Idis to typ. 0.7 V. Time delay, td, is as follows: With C5 = 330 nF and VBatt = 12 V, we have Current Limitation The lamp current is limited by a control amplifier that protects the external power transis- tor. The voltage drop across an external shunt resistor acts as the measured variable. Current limitation takes place for a voltage drop of V T1 ≈ 100 mV. Owing to the differ- ence VT -V T2 ≈ 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. Pins 13 and 14 – Charge Pump and Output Pin 14 (output) is suitable for controlling a power MOSFET. During the active integration phase, the supply current of the operational amplifier is mainly supplied by capacitor C 3 (bootstrapping). Additionally, a trickle charge is generated by an integrated oscillator 13 ≈ 400 kHz) and a voltage doubler circuit. This permits a gate voltage supply at a duty cycle of 100%. Pin 16 – Supply Voltage, Vs or VBatt Undervoltage Detection In the event of voltages of approximately V Batt < 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 of VBatt > 20 V (typically) occur, the external transistor is switched off and switched on again at VBatt < 18.5 V (hysteresis). Stage 2 If VBatt > 28.5 V (typically), 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 pro- ducing voltage sharing between the FET and lamps in the event of overvoltage pulses (e.g., load-dump). The short-circuit protection is not in operation. At V Batt < 23 V, the overvoltage detection stage 2 is switched off. td C5 V11 0.7 V–() td 330 nF 9.8 V 0.7 V–()

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4677B–AUTO–02/04 Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability Parameters Symbol Value Unit Junction temperature T j 150 °C Ambient temperature range T amb -40 to +110 °C Storage temperature range T stg -55 to +125 °C Thermal Resistance Parameters Symbol Value Unit Junction ambient R thJA 120 K/W

Electrical Characteristics

Tamb = -40 to +110°C, V Batt = 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 on page 1). All other values refer to pin GND (pin 1). Parameters Test Conditions Symbol Min. Typ. Max. Unit Current consumption Pin 16 I S 6.8 mA Supply voltage Overvoltage detection, stage 1 V Batt 25 V Stabilized voltage I S = 10 mA, pin 16 V S 24.5 27.0 V Battery undervoltage detection - on - off VBatt 4.4 4.8 5.0 5.4 5.6 6.0 V Battery Overvoltage Detection Pin 2 Stage 1: - on - off VBatt 18.3 16.7 20.0 18.5 21.7 20.3 V Stage 2: - on - off VBatt 25.5 19.5 28.5 23.0 32.5 26.5 V Stabilized voltage I S = 30 mA, pin 16 V Z 18.5 20.0 21.5 V Short-circuit Protection Pin 12 Short-circuit current limitation V T1 = VS -V 12 VT1 85 100 120 mV Short-circuit detection VT2 = VS -V 12 VT2 75 90 105 mV VT1 -V T2 31 0 3 0 m V Delay Timer Short-circuit Detection Pin 11 Switched off threshold V T11 = VS - V11 VT11 9.5 9.8 10.1 V Charge current I ch 23 µA Discharge current I dis 3µ A Capacitance current I 5 = Ich - Idis I5 13 20 27 mA Output short-circuit latch Pin 9 Saturation voltage I 9 = 100 µA V sat 150 350 mV Notes: 1. Reference point is battery ground

4677B–AUTO–02/04 Voltage Doubler Pin 13 Voltage Duty cycle 100% V 13 2V S Oscillator frequency f 13 280 400 520 kHz Internal voltage limitation I13 = 5 mA V 13 26 27.5 30.0 V (whichever is lower) V 13 (VS+14)( V S+15)( V S+16) Gate Output Pin 14 Voltage Low level V 14 0.35 0.70 0.95 VVBatt = 16.5 V, Tamb = 110°C, R3 =1 5 0Ω 1.5(1) High level, duty cycle 100% V 14 V13 Current V14 = Low level I 14 1.0 mA V14 = High level, I13 >  I14 -1.0 Enable/Disable Pin 2 Current V 2 = 0 V I 2 -20 -40 -60 µA Duty Cycle Reduction Pin 4 Z-voltage I 4 = 500 µA V 4 6.9 7.4 8.0 V Oscillator Frequency Pin6 f 10 2000 Hz Threshold cycle Upper Lower α 1 0.68 0.7 0.72 α2 0.65 0.67 0.69 α3 0.26 0.28 0.3 Oscillator current V Batt = 12 V ±I osc 26 40 54 µA Frequency tolerance C4 open, C2 = 470 nF , duty cycle = 50% f 6.0 9.9 13.5 Hz Electrical Characteristics (Continued) Tamb = -40 to +110°C, V Batt = 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 on page 1). All other values refer to pin GND (pin 1). Parameters Test Conditions Symbol Min. Typ. Max. Unit Notes: 1. Reference point is battery ground V14 High, α1 VT100 VS V14 Low, α2 VT<100 VS VTL VS

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Figure 3. Application

4677B–AUTO–02/04

Package Information

Revision History Please note that the referring page numbers in this section are referred to the specific revision mentioned, not to this document. Changes from Rev. 4677A - 02/03 to Rev. 4677B - 02/04 1. Block Diagram on page 1 changed. 2. New heading rows at Table “Absolute Maximum Ratings” on page 6 added.

Ordering Information

Extended Type Number Package Remarks U6084B-FP SO16 – technical drawings according to DIN specifications Dimensions in mm 10.0 9.85 8.89 0.4 1.27 1.4 0.25 0.10 5.2 4.8 3.7 3.8 6.15 5.85 0.2 16 9

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