TEA1791AT GreenChip synchronous rectifier controller Rev. 01 — 7 June 2010 Product data sheet 1. General description The TEA1791AT is a member of the new generation of Synchronous Rectifier (SR) controller ICs for switched mode power supplies. Its high level of integration allows the design of a cost-effective power supply with a very low number of external components. The TEA1791AT is a controller IC dedicated for synchronous rectification on the secondary side of discontinuous conduction mode and quasi-resonant flyback converters. The TEA1791AT is fabricated in a Silicon On Insulator (SOI) process. 2. Features and benefits 2.1 Distinctive features Accurate synchronous rectification functionality Wide supply voltage range (8.5 V to 38 V) High level of integration, resulting in a very low external component count High driver output voltage of 10 V to drive all MOSFET brands to the lowest RDSon 2.2 Green features Low current consumption High system efficiency from no load to full load 2.3 Protection features Undervoltage protection 3. Applications The TEA1791AT is intended for adapters. The device can also be used in all other discontinuous conduction mode systems and quasi-resonant flyback systems that demand a highly efficient and cost-effective solution. 4. Ordering information Table 1. Ordering information Type number TEA1791AT/N1 Package Name Description Version SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 5. Block diagram VCC 8 SRSENSE 1 control Q R DRIVER TIMER 0.93 μs 4 Q S 0.99 μs −310 mV 3, 5, 6, 7 −55 mV 2 n.c. Fig 1. −12 mV GND 014aaa893 Block diagram 6. Pinning information 6.1 Pinning SRSENSE 1 GND 2 8 VCC 7 n.c. TEA1791AT n.c. 3 6 n.c. DRIVER 4 5 n.c. 014aaa894 Fig 2. Pin configuration 6.2 Pin description Table 2. TEA1791AT Product data sheet Pin description Symbol Pin Description SRSENSE 1 synchronous timing input GND 2 ground n.c. 3 not connected DRIVER 4 driver output for SR MOSFET n.c 5 not connected n.c. 6 not connected n.c. 7 not connected VCC 8 supply voltage All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 2 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 7. Functional description 7.1 Introduction The TEA1791AT is the controller for synchronous rectification to be used in discontinuous conduction mode and quasi-resonant flyback converters. 7.2 Start-up and UnderVoltage LockOut (UVLO) The IC leaves the undervoltage lockout state and activates the synchronous rectifier circuitry as soon as the voltage on the VCC pin is above 8.5 V (typical). As soon as the voltage drops below 8.0 V (typical), the undervoltage lockout state is reentered and the SR driver output is actively kept low. 7.3 Synchronous rectification After a negative voltage (−310 mV typical) is sensed on the SRSENSE pin, the driver output voltage is driven HIGH and the external MOSFET is switched on. As soon as the SRSENSE voltage rises to −55 mV the driver output voltage is regulated to maintain the −55 mV on the SRSENSE pin. As soon as the SRSENSE voltage is above −12 mV, the driver output is pulled to ground. When the SR MOSFET is switched on, the input signal on the SRSENSE pin is blanked for 0.93 μs (typical). This eliminates false switch-off due to high frequency at the start of the secondary stroke. Because the driver output voltage is reduced as soon as the voltage on the SRSENSE pin is −55 mV, the external power switch can be switched off quickly when the current through the switch reaches zero. With this zero current switch-off, no separate Standby mode is needed to maintain high efficiency during the no-load operation. The zero current is detected by sensing a −12 mV level on the SRSENSE pin (see Figure 3). TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 3 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller VSRSENSE 0V −12 mV −55 mV −310 mV Primary current 0A Secondary current 0A VDRIVER 0V 014aaa057 Fig 3. Synchronous rectification signals If the secondary stroke of the flyback converter is shorter than 0.93 μs (typical), the driver output is disabled. This will guarantee stable operation for very low duty cycles. When the secondary stroke increases above 0.99 μs (typical), the driver output is again enabled. 7.4 Supply management All internal reference voltages are derived from a temperature compensated, on-chip band gap circuit. 7.5 Driver The driver circuit to the gate of the external power MOSFET has a typical source capability of 250 mA and a typical sink capability of 2.7 A. This permits fast turn-on and turn-off of the power MOSFET for efficient operation. The source stage is coupled to the timer (see Figure 1). When the timer has finished, the source capability is reduced to a small current (typical 5 mA) capable of keeping the driver output voltage at its level. Typically, the time the driver source stage delivers the 250 mA is 100 ns shorter than the minimum synchronous rectification active time (tact(sr)(min)).The output voltage of the driver is limited to 10 V (typical). This high output voltage will drive all MOSFET brands to the minimum on-state resistance. During start-up conditions (VCC < Vstartup) and undervoltage lockout the driver output voltage is actively pulled low. TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 4 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 8. Limiting values Table 3. Limiting values In accordance with the Absolute Maximum Rating System (IEC 60134). All voltages are measured with respect to ground (pin 2). Positive currents flow into the chip. The voltage and current ratings are valid provided the other ratings are not violated. Symbol Parameter Conditions Min Max Unit VCC supply voltage continuous −0.4 +38 V VSRSENSE voltage on pin SRSENSE continuous - 120 V IDRIVER current on pin DRIVER duty cycle < 10 % −0.8 +3 A ISRSENSE current on pin SRSENSE −3 - mA Voltages Currents General Tamb < 80 °C Ptot total power dissipation - 0.45 W Tstg storage temperature −55 +150 °C Tj junction temperature −40 +150 °C VESD electrostatic discharge voltage class 2 human body model [1] - 2000 V machine model [2] - 200 V - 500 V charged device model [1] Equivalent to discharging a 100 pF capacitor through a 1.5 kΩ series resistor. [2] Equivalent to discharging a 200 pF capacitor through a 0.75 μH coil and a 10 Ω series resistor. 9. Thermal characteristics Table 4. TEA1791AT Product data sheet Thermal characteristics Symbol Parameter Conditions Typ Unit Rth(j-a) thermal resistance from junction to ambient in free air 150 K/W Rth(j-c) thermal resistance from junction to case 95 K/W All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 5 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 10. Characteristics Table 5. Characteristics Tamb = 25 °C; VCC = 20 V; all voltages are measured with respect to ground (pin 2); currents are positive when flowing into the IC; unless otherwise specified. Symbol Parameter Conditions Min Typ Max Unit 8.2 8.5 8.8 V - 0.5 - V - 0.65 - mA - 0.95 - mA −310 −280 mV Supply voltage management (pin VCC) Vstartup start-up voltage [1] Vhys hysteresis voltage ICC(oper) operating supply current VCC = 8 V (VCC < Vstartup) under normal operation; no load on pin DRIVER Synchronous rectification sense input (pin SRSENSE) Vact(drv) driver activation voltage −340 Vreg(drv) driver regulation voltage −65 −55 −45 mV Vdeact(drv) driver deactivation voltage - −12 - mV td(act)(drv) driver activation delay time - 125 - ns tact(sr)(min) minimum synchronous rectification Short time 0.7 0.93 1.16 μs Long time 0.75 0.99 1.23 μs −0.3 −0.25 −0.2 A voltage on pin DRIVER = 2 V 1 1.4 - A voltage on pin DRIVER = 9.5 V 2.2 2.7 - A - 10 12 V Driver (pin DRIVER) Isource source current VCC = 15 V; voltage on pin DRIVER = 2 V Isink sink current VCC = 15 V Vo(max) [1] maximum output voltage VCC = 15 V The VCC stop voltage is Vstartup − Vhys. TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 6 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 11. Application information A switched mode power supply with the TEA1791AT consists of a primary side discontinuous conduction mode flyback controller, a transformer, and an output stage with a feedback circuit. A MOSFET (Qsec) is used for low conduction losses in the output stage. This MOSFET is controlled by the TEA1791AT. The timing for the synchronous rectifier switch is derived from the voltage sensed on the SRSENSE pin. The resistor in the SRSENSE connection is needed to protect the TEA1791AT from excessive voltages. The RSRSENSE resistor should typically be 1 kΩ. Higher values might impair correct timing and lower values may not provide sufficient protection. TR Qsec Vout RSRSENSE Vin GND Qprim PRIMARY SIDE CONTROLLER VCC DRIVER Cout TEA1791AT SRSENSE 014aaa896 Fig 4. Application diagram high side rectification TR Vin Vout VCC RSRSENSE PRIMARY SIDE CONTROLLER Qprim Qsec SRSENSE TEA1791AT Cout DRIVER GND 014aaa897 Fig 5. TEA1791AT Product data sheet Application diagram low side rectification All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 7 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller Vin Qprim1 PRIMARY SIDE CONTROLLER Tr CHB Qprim2 Vout VCC VCC SRSENSE RSRSENSE1 Qsec1 DRIVER SRSENSE TEA1791AT IC1 GND RSRSENSE2 Qsec2 DRIVER Cout TEA1791AT IC2 GND 014aaa895 Fig 6. TEA1791AT Product data sheet Application diagram resonant application All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 8 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 12. 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 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 inches 0.244 0.039 0.028 0.041 0.228 0.016 0.024 θ o 8 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 7. 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) TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 9 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 13. Revision history Table 6. Revision history Document ID Release date Data sheet status Change notice Supersedes TEA1791AT v.1 20100607 Product data sheet - - TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 10 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 14. Legal information 14.1 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. 14.2 Definitions Draft — The document is a draft version only. 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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. Customers are responsible for the design and operation of their applications and products using NXP Semiconductors products, and NXP Semiconductors accepts no liability for any assistance with applications or customer product design. It is customer’s sole responsibility to determine whether the NXP Semiconductors product is suitable and fit for the customer’s applications and products planned, as well as for the planned application and use of customer’s third party customer(s). Customers should provide appropriate design and operating safeguards to minimize the risks associated with their applications and products. NXP Semiconductors does not accept any liability related to any default, damage, costs or problem which is based on any weakness or default in the customer’s applications or products, or the application or use by customer’s third party customer(s). Customer is responsible for doing all necessary testing for the customer’s applications and products using NXP Semiconductors products in order to avoid a default of the applications and the products or of the application or use by customer’s third party customer(s). NXP does not accept any liability in this respect. Limiting values — Stress above one or more limiting values (as defined in the Absolute Maximum Ratings System of IEC 60134) will cause permanent damage to the device. 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Export might require a prior authorization from national authorities. TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 11 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller Non-automotive qualified products — Unless this data sheet expressly states that this specific NXP Semiconductors product is automotive qualified, the product is not suitable for automotive use. It is neither qualified nor tested in accordance with automotive testing or application requirements. NXP Semiconductors accepts no liability for inclusion and/or use of non-automotive qualified products in automotive equipment or applications. In the event that customer uses the product for design-in and use in automotive applications to automotive specifications and standards, customer (a) shall use the product without NXP Semiconductors’ warranty of the product for such automotive applications, use and specifications, and (b) whenever customer uses the product for automotive applications beyond NXP Semiconductors’ specifications such use shall be solely at customer’s own risk, and (c) customer fully indemnifies NXP Semiconductors for any liability, damages or failed product claims resulting from customer design and use of the product for automotive applications beyond NXP Semiconductors’ standard warranty and NXP Semiconductors’ product specifications. 14.4 Trademarks Notice: All referenced brands, product names, service names and trademarks are the property of their respective owners. GreenChip — is a trademark of NXP B.V. 15. Contact information For more information, please visit: http://www.nxp.com For sales office addresses, please send an email to: [email protected] TEA1791AT Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 01 — 7 June 2010 © NXP B.V. 2010. All rights reserved. 12 of 13 TEA1791AT NXP Semiconductors GreenChip synchronous rectifier controller 16. Contents 1 2 2.1 2.2 2.3 3 4 5 6 6.1 6.2 7 7.1 7.2 7.3 7.4 7.5 8 9 10 11 12 13 14 14.1 14.2 14.3 14.4 15 16 General description . . . . . . . . . . . . . . . . . . . . . . 1 Features and benefits . . . . . . . . . . . . . . . . . . . . 1 Distinctive features . . . . . . . . . . . . . . . . . . . . . . 1 Green features . . . . . . . . . . . . . . . . . . . . . . . . . 1 Protection features . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Ordering information . . . . . . . . . . . . . . . . . . . . . 1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Pinning information . . . . . . . . . . . . . . . . . . . . . . 2 Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 2 Functional description . . . . . . . . . . . . . . . . . . . 3 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Start-up and UnderVoltage LockOut (UVLO) . . 3 Synchronous rectification . . . . . . . . . . . . . . . . . 3 Supply management. . . . . . . . . . . . . . . . . . . . . 4 Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . . 5 Thermal characteristics . . . . . . . . . . . . . . . . . . 5 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Application information. . . . . . . . . . . . . . . . . . . 7 Package outline . . . . . . . . . . . . . . . . . . . . . . . . . 9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . 10 Legal information. . . . . . . . . . . . . . . . . . . . . . . 11 Data sheet status . . . . . . . . . . . . . . . . . . . . . . 11 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 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. 2010. 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: 7 June 2010 Document identifier: TEA1791AT