UBA3070 LED backlight driver IC Rev. 02 — 2 December 2008 Product data sheet 1. General description The UBA3070 driver IC is the first member of a first generation of power-efficient LED backlight driver ICs. Highly efficient, flexible and reliable LED drivers can easily be designed using the UBA3070 control IC. 2. Features n Switch-mode buck controller that drives strings of LEDs up to 600 V power-efficiently n Controller with power-efficient boundary conduction mode of operation: u No reverse recovery losses in freewheel diode u Zero current switching for turn-on of switch u Zero voltage or valley switching for turn-on of switch u Minimal required inductance value and size n Direct Pulse Width Modulation (PWM) dimming available n Fast transient response through cycle-by-cycle current control, thereby: u Preventing over or undershoots in the LED current u Enabling efficient PWM dimming by quickly turning the converter on and off and thereby removing the need for extra dim switches and high-side drivers n Single loosely controlled input voltage required for all LED strings in RGB backlights n No binning on LED forward voltage required n Protections: u Undervoltage lockout u Leading edge blanking u Overcurrent u Overtemperature n Low cost LED driver solution: u No Schottky diode required because of zero-current switching u No dim switch and high-side driver required for PWM dimming u Smaller inductor possible compared to fixed-frequency continuous conduction mode controllers 3. Applications n The UBA3070 is typically suited as a high voltage LED backlighting application in LCD televisions and monitors (See Figure 1) UBA3070 NXP Semiconductors LED backlight driver IC 4. Ordering information Table 1. Ordering information Type number UBA3070T Package Name Description Version SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1 5. Block diagram VCC 1 8 VALLEY SUPPLY MANAGEMENT DRAIN clamp Iprot(mask) Internal UVLO Start supply 2 GND 4 LOGIC MASK OSCILLATOR 100 mV MASK PROTECTION Iprot(PWM) 3 PWM 6 LOGIC GATE DRIVER Istartup(soft) POWER-ON RESET LEB S soft start S2 Q Blank UVLO OVERTEMPERATURE PROTECTION R 0.5 V Q 5 VCC < 4.5 V S Q R Q − Short winding RSENSE 0.5 V 0.88 V 014aaa257 Fig 1. Block diagram of single channel 8-pin LED backlight controller IC UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 2 of 13 UBA3070 NXP Semiconductors LED backlight driver IC Vin 12 V VCC GND PWM PWM MASK 1 8 2 7 UBA3070 3 6 4 5 DRAIN HVS GATE RSENSE 014aaa092 Fig 2. Basic application diagram 6. Pinning information 6.1 Pinning VCC 1 GND 2 8 DRAIN 7 HVS UBA3070 PWM 3 6 GATE MASK 4 5 RSENSE 014aaa094 Fig 3. Pin configuration SO8 6.2 Pin description Table 2. Pin description Symbol Pin Description SO8 VCC 1 supply voltage GND 2 ground PWM 3 PWM input voltage MASK 4 masking input voltage SENSE 5 resistor programmable current sense input UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 3 of 13 UBA3070 NXP Semiconductors LED backlight driver IC Table 2. Pin description …continued Symbol Pin Description SO8 GATE 6 gate driver output HVS 7 high voltage safety spacer: not connected DRAIN 8 drain of external MOS switch: input for valley sensing 7. Functional description The UBA3070 is a monolithic driver IC for controlling the current through LED strings and is especially suitable as driver stage for LED Backlighting applications like LCD televisions. The driver stage enables optimal performance for series connected LED strings in 0D, 1D and 2D segmented backlight units (BLUs). Since the UBA3070 drives an external power device, it can be used for all kinds of BLU designs ranging from high-power to low-power LEDs, and high-voltage to low-voltage LED strings. Consequently it provides a driver solution for all LCD screen sizes and types of LEDs. By combining the UBA3070 with the appropriate power devices, the amount of drivers can be minimized by optimizing the amount of LEDs put in series. Each driver stage consists of a buck converter operating in boundary conduction mode of which the peak level can be chosen by means of the external sense resistor. Since the peak and zero levels are fixed by design, the converter behaves as a current source. This gives an average current through the LEDs that is half the peak value of that through the inductor. The ripple current through the LEDs can be chosen by means of the external capacitor in parallel to the LEDs. 7.1 Supply management and undervoltage lockout As long as VCC is below the VCC(startup) level of typically 10 V, the supply current is below 600 µA. The IC will activate the converter as soon as the voltage on the VCC pin passes the VCC(startup) level. The moment the voltage on pin VCC drops below the undervoltage lockout voltage of typically 8.7 V the IC stops switching. 7.2 Current control and PWM If the PWM input is high (> 2 V) the converter is disabled, it will not switch and the LED current is zero. If the PWM input pin is low (< 0.5 V) the converter is enabled and operation is as follows. The external FET is turned on and current in the inductor will build up. During this charging phase of the inductor the current is sensed across an external sense resistor. The internal driver turns off the external FET upon detection of a voltage level of typically 0.52 V at the SENSE pin. The inductor will freewheel its current through the external diode and will discharge. After discharge the switch node will ring. Upon detection of a valley or zero voltage on the switch node the internal driver will turn on the external FET. Consequently turn-on of the FET is at zero current and at minimal voltage resulting in minimal power losses and EMI. The conversion cycle will repeat as described above, until the PWM input signal is driven high to disable the converter and steer the LED current to zero. UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 4 of 13 UBA3070 NXP Semiconductors LED backlight driver IC If the PWM pin is open circuit or not connected, a fault condition is assumed and the converter will stop switching. Operation will recommence as soon as the fault condition is removed. 7.3 Masking and valley switching The mask pin ensures that turn-on of the converter is at a valley during ringing and not at a peak during freewheeling of the inductor. If the voltage level at the mask pin is typically above 100 mV, then turn-on of the switching FET is prevented. If the voltage level is below this 100 mV, then turn-on prevention of the FET is released and at the moment of valley detection the FET will actually turn on. The signal for the mask pin can be easily derived from the signal at the switch node as shown in the application diagram. The current flowing into the mask pin should be lower than the typical stop current of 60 µA. If pin MASK is open circuit or not connected, a fault condition is assumed and the converter will stop operating immediately. Operation will recommence as soon as the fault condition is removed. 7.4 Conversion frequency The maximum conversion frequency is limited to minimally 145 kHz by an internal oscillator. Consequently the inductance value should be chosen such that with the given supply voltage, LED voltage and component spread the conversion frequency is always smaller than this. There is no limitation for the minimum conversion frequency. 7.5 Minimum on-time The minimum on-time of the switch mode converter is determined by the leading edge blanking time of typically 370 ns. The leading edge blanking time is required to prevent inadvertent switch off after turn on of the FET due to coupling to the sense node. 7.6 Overcurrent protection Since the converter behaves as a current source it is principally self-protected from overcurrent. An extra level of protection is added by means of a second trip level at typically 0.88 V at the sense node to protect against short-circuits in external components like diodes, inductors, capacitors or LEDs. Upon detection of this abnormal situation the converter will stop switching. 7.7 Soft start-up (pin SENSE) To have slow start-up the inductor peak current is slowly increased by the soft start-up function. This can be achieved by inserting a resistor and a capacitor between the SENSE-pin (pin 5) and sense resistor Rsense. An internal current source charges the capacitor to V SENSE = I ch × R ss (about 0.5 V maximum). The start level and the time constant of the increasing primary current level can be adjusted externally by changing the values of Rss and Css. V sense ( max ) – ( I ch × R ss ) I DM = ------------------------------------------------------------R sense τ = R ss × C ss UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 5 of 13 UBA3070 NXP Semiconductors LED backlight driver IC The charge current Ich will flow as long as the voltage on pin SENSE is below approximately 0.5 V. If the voltage on pin SENSE exceeds 0.5 V, the soft start current source will start limiting current Ich. At Vstartup, the Ich current source is completely switched off, see Figure 4. Istartup(soft) 0.5 V start-up 6 SENSE Vocp Rss Css Rsense 014aaa254 Fig 4. Soft start-up 7.8 Overtemperature protection An accurate temperature protection is provided in the UBA3070. When the junction temperature exceeds the thermal shutdown temperature of typically 140 °C the converter will stop switching. 7.9 Driver The driver circuit to the gate of the power FET has a current sourcing capability of 135 mA typical and a current sinking capability of 560 mA typical. This permits fast turn-on and turn-off of the FET for efficient operation. A low driver source current has been chosen to limit the ∆V/∆t at turn-on thereby reducing EMI and voltage spikes across Rsense.The driver circuit to the gate of the power MOSFET has a current sourcing capability of 135 mA typical and a current sink capability of 560 mA typical. This permits fast turn-on and turn-off of the power MOSFET for efficient operation. 8. Limiting values Table 3. Limiting values In accordance with the Absolute Maximum Rating System (IEC 60134).[1] Symbol Unit[1] Parameter Conditions Min Max VCC supply voltage current limited −0.4 +20 V VPWM voltage on pin PWM −0.4 +5 V VMASK voltage on pin MASK current limited −0.4 - V VSENSE voltage on pin SENSE current limited −0.4 - V VDRAIN voltage on pin DRAIN −0.4 +650 V 5 mA Voltages Currents IPWM current on pin PWM UBA3070_2 Product data sheet - © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 6 of 13 UBA3070 NXP Semiconductors LED backlight driver IC Table 3. Limiting values …continued In accordance with the Absolute Maximum Rating System (IEC 60134).[1] Conditions Min Parameter IMASK current on pin MASK −250 +250 µA ISENSE current on pin SENSE −1 +10 mA IGATE current on pin GATE IDRAIN current on pin DRAIN d < 10 % Max Unit[1] Symbol −0.8 +2 A - 5 mA - 0.5 W General Tamb < 70 °C Ptot total power dissipation Tstg storage temperature −55 +150 °C Tj junction temperature −40 +145 °C ESD electrostatic discharge voltage VESD all pins except pins DRAIN and VCC; HBM class 1 [2] - 2000 V pins DRAIN and VCC; HBM class 1 [2] - 1500 V any pin; MM [3] - 200 V [1] All voltages are measured with respect to ground; positive currents flow into the IC. The pin VCC may not be current driven. The voltage ratings are valid provided other ratings are not violated. The current ratings are valid provided the maximum power rating is not violated. [2] Human Body Model (HBM): equivalent to discharging a 100 pF capacitor through a 1.5 kΩ resistor. [3] Machine Model (MM): equivalent to discharging a 200 pF capacitor through a 0.75 µH coil and a 10 Ω resistor. 9. Thermal characteristics Table 4. Thermal characteristics Symbol Parameter Conditions Typ Unit Rth(j-a) thermal resistance from junction to ambient In free air 150 K/W 10. Characteristics Table 5. Characteristics Tamb = 25 ° C; VCC = 15 V; all voltages are measured with respect to ground; currents are positive when flowing into the IC; unless otherwise specified. Symbol Parameter Conditions Min Typ Max Unit 650 - - V Start-up current source (pin DRAIN) VBR breakdown voltage Supply voltage management (pin VCC) VCC(startup) start-up supply voltage 9.3 10 10.6 V VCC(UVLO) undervoltage lockout supply voltage 8.1 8.7 9.3 V VCC(hys) hysteresis of supply voltage 1.0 1.3 1.6 V VCC(startup) − VCC(UVLO) UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 7 of 13 UBA3070 NXP Semiconductors LED backlight driver IC Table 5. Characteristics …continued Tamb = 25 ° C; VCC = 15 V; all voltages are measured with respect to ground; currents are positive when flowing into the IC; unless otherwise specified. Symbol Parameter Conditions Min Typ Max Unit ICC(oper) operating supply current no load on pin GATE 1.1 1.3 1.5 mA ICC(startup) start-up supply current VCC < VCC(startup) - - 600 µA ICC(prot) protection supply current VCC > VCC(UVLO) - 0.85 - mA 50 100 150 mV Masking management (pin MASK) Vth(MASK) threshold voltage on pin MASK Vclamp(neg)(MASK) negative clamp voltage on pin MASK IMASK = −150 µA −0.5 −0.25 −0.05 V Vclamp(pos)(MASK) positive clamp voltage on pin MASK IMASK = 250 µA 0.5 0.7 0.9 V Istop(pos)(MASK) positive stop current on pin MASK 54 60 66 µA tsup(xfmr_ring) transformer ringing suppression time start secondary shock 1.1 1.5 1.9 µs Iprot(MASK) protection current on pin MASK VMASK = 50 mV −50[1] - −10 nA high oscillator frequency VPWM is low 145 175 205 kHz [2] - - 0.5 V [2] 2.0 - - V −1.0[1] −0.8 −0.5 µA Oscillator fosc(high) PWM duty cycle control (pin PWM) VIL(en)ILED(PWM) LED current enable LOW-level input voltage on pin PWM VIH(dis)ILED(PWM) LED current disable HIGH-level input voltage on pin PWM Iprot(PWM) protection current on pin PWM VPWM = 1.5 V Valley switch (pin DRAIN) (∆V/∆t)vrec valley recognition voltage change with time −85 - +85 V/µs td(vrec-swon) valley recognition to switch-on delay time - 150[1] - ns Overcurrent protection (pin SENSE) Vsense(max) maximum sense voltage ∆V/∆t = 0.1 V/µs 0.48 0.52 0.56 V tPD propagation delay ∆V/∆t = 0.5 V/µs - 140 185 ns Vswp short-winding protection voltage 0.83 0.88 0.95 V tleb leading edge blanking time 300 370 440 ns Istartup(soft) soft startup current Rsense < 0.5 V 45 60 75 µA Driver (pin GATE) Isource source current VCC = 9.5 V; VDRIVER = 2 V - −135 - mA Isink sink current VCC= 9.5 V; VDRIVER = 2 V - 240 - mA VCC = 9.5 V; VDRIVER = 9.5 V - 560 - mA VCC > 12 V - 11.5 12 V Vo(max) maximum output voltage UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 8 of 13 UBA3070 NXP Semiconductors LED backlight driver IC Table 5. Characteristics …continued Tamb = 25 ° C; VCC = 15 V; all voltages are measured with respect to ground; currents are positive when flowing into the IC; unless otherwise specified. Symbol Parameter Conditions Min Typ Max Unit Overtemperature protection Tpl(max) maximum protection level temperature 130 140 150 °C Tpl(hys) protection level hysteresis temperature - 8 - °C [1] Guaranteed by design. [2] When the voltage at pin PWM is between 0.5 V and 2.0 V the peak current and the frequency will be reduced. UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 9 of 13 UBA3070 NXP Semiconductors LED backlight driver IC 11. Package outline SO8: plastic small outline package; 8 leads; body width 3.9 mm SOT96-1 D E A X c y HE v M A Z 5 8 Q A2 A (A 3) A1 pin 1 index θ Lp 1 L 4 e detail X w M bp 0 2.5 5 mm scale DIMENSIONS (inch dimensions are derived from the original mm dimensions) UNIT A max. A1 A2 A3 bp c D (1) E (2) e HE L Lp Q v w y Z (1) mm 1.75 0.25 0.10 1.45 1.25 0.25 0.49 0.36 0.25 0.19 5.0 4.8 4.0 3.8 1.27 6.2 5.8 1.05 1.0 0.4 0.7 0.6 0.25 0.25 0.1 0.7 0.3 inches 0.069 0.010 0.057 0.004 0.049 0.01 0.019 0.0100 0.014 0.0075 0.20 0.19 0.16 0.15 0.05 0.01 0.01 0.004 0.028 0.012 0.244 0.039 0.028 0.041 0.228 0.016 0.024 θ 8o o 0 Notes 1. Plastic or metal protrusions of 0.15 mm (0.006 inch) maximum per side are not included. 2. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included. Fig 5. REFERENCES OUTLINE VERSION IEC JEDEC SOT96-1 076E03 MS-012 JEITA EUROPEAN PROJECTION ISSUE DATE 99-12-27 03-02-18 Package outline SOT96-1(SO8) UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 10 of 13 UBA3070 NXP Semiconductors LED backlight driver IC 12. Revision history Table 6. Revision history Document ID Release date Data sheet status Change notice Supersedes UBA3070_2 20081202 Product data sheet - UBA3070_1 Modifications: UBA3070_1 • The minimum value for junction temperature has been updated in Table 3. 20080605 Product data sheet UBA3070_2 Product data sheet - - © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 11 of 13 UBA3070 NXP Semiconductors LED backlight driver IC 13. Legal information 13.1 Data sheet status Document status[1][2] Product status[3] Definition Objective [short] data sheet Development This document contains data from the objective specification for product development. Preliminary [short] data sheet Qualification This document contains data from the preliminary specification. Product [short] data sheet Production This document contains the product specification. [1] Please consult the most recently issued document before initiating or completing a design. [2] The term ‘short data sheet’ is explained in section “Definitions”. [3] The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status information is available on the Internet at URL http://www.nxp.com. 13.2 Definitions Draft — The document is a draft version only. The content is still under internal review and subject to formal approval, which may result in modifications or additions. NXP Semiconductors does not give any representations or warranties as to the accuracy or completeness of information included herein and shall have no liability for the consequences of use of such information. Short data sheet — A short data sheet is an extract from a full data sheet with the same product type number(s) and title. A short data sheet is intended for quick reference only and should not be relied upon to contain detailed and full information. For detailed and full information see the relevant full data sheet, which is available on request via the local NXP Semiconductors sales office. In case of any inconsistency or conflict with the short data sheet, the full data sheet shall prevail. 13.3 Disclaimers General — Information in this document is believed to be accurate and reliable. However, NXP Semiconductors does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. Right to make changes — NXP Semiconductors reserves the right to make changes to information published in this document, including without limitation specifications and product descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof. Suitability for use — NXP Semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or malfunction of an NXP Semiconductors product can reasonably be expected to result in personal injury, death or severe property or environmental damage. NXP Semiconductors accepts no liability for inclusion and/or use of NXP Semiconductors products in such equipment or applications and therefore such inclusion and/or use is at the customer’s own risk. Applications — Applications that are described herein for any of these products are for illustrative purposes only. NXP Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Limiting values — Stress above one or more limiting values (as defined in the Absolute Maximum Ratings System of IEC 60134) may cause permanent damage to the device. Limiting values are stress ratings only and operation of the device at these or any other conditions above those given in the Characteristics sections of this document is not implied. Exposure to limiting values for extended periods may affect device reliability. Terms and conditions of sale — NXP Semiconductors products are sold subject to the general terms and conditions of commercial sale, as published at http://www.nxp.com/profile/terms, including those pertaining to warranty, intellectual property rights infringement and limitation of liability, unless explicitly otherwise agreed to in writing by NXP Semiconductors. In case of any inconsistency or conflict between information in this document and such terms and conditions, the latter will prevail. No offer to sell or license — Nothing in this document may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights. 13.4 Trademarks Notice: All referenced brands, product names, service names and trademarks are the property of their respective owners. 14. Contact information For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: [email protected] UBA3070_2 Product data sheet © NXP B.V. 2008. All rights reserved. Rev. 02 — 2 December 2008 12 of 13 UBA3070 NXP Semiconductors LED backlight driver IC 15. Contents 1 2 3 4 5 6 6.1 6.2 7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8 9 10 11 12 13 13.1 13.2 13.3 13.4 14 15 General description . . . . . . . . . . . . . . . . . . . . . . 1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Ordering information . . . . . . . . . . . . . . . . . . . . . 2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Pinning information . . . . . . . . . . . . . . . . . . . . . . 3 Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 3 Functional description . . . . . . . . . . . . . . . . . . . 4 Supply management and undervoltage lockout 4 Current control and PWM . . . . . . . . . . . . . . . . . 4 Masking and valley switching . . . . . . . . . . . . . . 5 Conversion frequency . . . . . . . . . . . . . . . . . . . . 5 Minimum on-time . . . . . . . . . . . . . . . . . . . . . . . 5 Overcurrent protection . . . . . . . . . . . . . . . . . . . 5 Soft start-up (pin SENSE). . . . . . . . . . . . . . . . . 5 Overtemperature protection . . . . . . . . . . . . . . . 6 Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . . 6 Thermal characteristics. . . . . . . . . . . . . . . . . . . 7 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Package outline . . . . . . . . . . . . . . . . . . . . . . . . 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . 11 Legal information. . . . . . . . . . . . . . . . . . . . . . . 12 Data sheet status . . . . . . . . . . . . . . . . . . . . . . 12 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Contact information. . . . . . . . . . . . . . . . . . . . . 12 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Please be aware that important notices concerning this document and the product(s) described herein, have been included in section ‘Legal information’. © NXP B.V. 2008. All rights reserved. For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: [email protected] Date of release: 2 December 2008 Document identifier: UBA3070_2