1. general description the TEA1791T is a member of the new generation of synchronous recti?er (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 TEA1791T is a controller ic dedicated for synchronous recti?cation on the secondary side of discontinuous conduction mode and quasi-resonant ?yback converters. the TEA1791T is fabricated in a silicon on insulator (soi) process. 2. features 2.1 distinctive features n accurate synchronous recti?cation functionality n wide supply voltage range (8.5 v to 38 v) n high level of integration, resulting in a very low external component count n high driver output voltage of 10 v to drive all mosfet brands to the lowest r dson 2.2 green features n low current consumption n high system ef?ciency from no load to full load 2.3 protection features n undervoltage protection 3. applications n the TEA1791T is intended for adapters. the device can also be used in all other discontinuous conduction mode systems and quasi-resonant ?yback systems that demand a highly ef?cient and cost-effective solution. 4. ordering information TEA1791T greenchip synchronous recti?er controller rev. 01 3 february 2009 product data sheet table 1. ordering information type number package name description version TEA1791T/n1 so8 plastic small outline package; 8 leads; body width 3.9 mm sot96-1
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 2 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 5. block diagram 6. pinning information 6.1 pinning 6.2 pin description fig 1. block diagram v cc 8 3, 5, 6, 7 n.c. 2 gnd srsense 1 4 r s q q - 55 mv driver control - 12 mv - 310 mv timer 2 m s 2.2 m s 014aaa700 fig 2. pin con?guration TEA1791T srsense v cc gnd n.c. n.c. n.c. driver n.c. 014aaa701 1 2 3 4 6 5 8 7 table 2. 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 v cc 8 supply voltage
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 3 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 7. functional description 7.1 introduction the TEA1791T is the controller for synchronous recti?cation to be used in discontinuous conduction mode and quasi-resonant ?yback converters. 7.2 start-up and undervoltage lockout (uvlo) the ic leaves the undervoltage lockout state and activates the synchronous recti?er circuitry as soon as the voltage on the v cc pin is above 8.5 v (typ). as soon as the voltage drops below 8.0 v (typ), the undervoltage lockout state is reentered and the sr driver output is actively kept low. 7.3 synchronous recti?cation after a negative voltage ( - 310 mv typ) 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. after switch-on of the sr mosfet, the input signal on the srsense pin is blanked for 2 m s (typ). this eliminates false switch-off due to high frequency ringing 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 ef?ciency during the no-load operation. the zero current is detected by sensing a - 12 mv level on the srsense pin (see figure 3 ).
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 4 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller if the secondary stroke of the ?yback converter is shorter than 2 m s (typ), the driver output is disabled. this will guarantee stable operation for very low duty cycles. when the secondary stroke increases above 2.2 m s (typ), 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 source capability of typically 250 ma and a sink capability of typically 2.7 a. this permits fast turn-on and turn-off of the power mosfet for ef?cient operation. 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 (v cc < v startup ) and undervoltage lockout the driver output voltage is actively pulled low. fig 3. synchronous recti?cation signals 014aaa057 0 v - 12 mv - 55 mv - 310 mv 0 a 0 a 0 v v srsense v driver primary current secondary current
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 5 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 8. limiting values [1] equivalent to discharging a 100 pf capacitor through a 1.5 k w series resistor. [2] equivalent to discharging a 200 pf capacitor through a 0.75 m h coil and a 1.5 k w series resistor. 9. thermal characteristics 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 ?ow into the chip. the voltage ratings are valid provided other ratings are not violated; current ratings are valid provided the other ratings are not violated. symbol parameter conditions min max unit voltages v cc supply voltage continuous - 0.4 +38 v v srsense voltage on pin srsense continuous - 120 v currents i driver current on pin driver duty cycle < 10 % - 0.8 +3 a i srsense current on pin srsense - 3- ma general p tot total power dissipation t amb <80 c - 0.45 w t stg storage temperature - 55 +150 c t j junction temperature - 20 +150 c v esd electrostatic discharge voltage class 2 human body model [1] - 2000 v machine model [2] - 200 v charged device model - 500 v table 4. thermal characteristics symbol parameter conditions typ unit r th(j-a) thermal resistance from junction to ambient in free air 150 k/w
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 6 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 10. characteristics [1] the v cc stop voltage is v startup - v hys . table 5. characteristics t amb =25 c; v cc = 20 v; all voltages are measured with respect to ground (pin 2); currents are positive when ?owing into the ic; unless otherwise speci?ed. symbol parameter conditions min typ max unit supply voltage management (pin v cc ) v startup start-up voltage 8.2 8.5 8.8 v v hys hysteresis voltage [1] - 0.5 - v i cc(oper) operating supply current v cc = 8 v (v cc TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 7 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 11. application information a switched mode power supply with the TEA1791T consists of a primary side discontinuous conduction mode ?yback controller, a transformer, and an output stage with a feedback circuit. in the output stage a mosfet (qsec) is used for low conduction losses. the mosfet is controlled by the TEA1791T. the timing for the synchronous recti?er switch is derived from the voltage sensed on the srsense pin. the resistor in the srsense connection is needed to protect the TEA1791T from excessive voltages. the srsense resistor should typically be 1 k w . higher values might impair correct timing, lower values may not provide suf?cient protection. fig 4. application diagram v in tr primary side controller q prim v cc gnd driver TEA1791T srsense qsec r srsense v out c out 014aaa702
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 8 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 12. package outline fig 5. package outline sot96-1 (so8) unit a max. a 1 a 2 a 3 b p cd (1) e (2) (1) eh e ll p qz y w v q references outline version european projection issue date iec jedec jeita mm inches 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 0.7 0.6 0.7 0.3 8 0 o o 0.25 0.1 0.25 dimensions (inch dimensions are derived from the original mm dimensions) 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. 1.0 0.4 sot96-1 x w m q a a 1 a 2 b p d h e l p q detail x e z e c l v m a (a ) 3 a 4 5 pin 1 index 1 8 y 076e03 ms-012 0.069 0.010 0.004 0.057 0.049 0.01 0.019 0.014 0.0100 0.0075 0.20 0.19 0.16 0.15 0.05 0.244 0.228 0.028 0.024 0.028 0.012 0.01 0.01 0.041 0.004 0.039 0.016 0 2.5 5 mm scale so8: plastic small outline package; 8 leads; body width 3.9 mm sot96-1 99-12-27 03-02-18
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 9 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 13. revision history table 6. revision history document id release date data sheet status change notice supersedes TEA1791T_1 20090203 product data sheet - -
TEA1791T_1 ? nxp b.v. 2009. all rights reserved. product data sheet rev. 01 3 february 2009 10 of 11 nxp semiconductors TEA1791T greenchip synchronous recti?er controller 14. legal information 14.1 data sheet status [1] please consult the most recently issued document before initiating or completing a design. [2] the term short data sheet is explained in section de?nitions. [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 dev ices. the latest product status information is available on the internet at url http://www .nxp .com . 14.2 de?nitions draft the document is a draft version only. the content is still under internal review and subject to formal approval, which may result in modi?cations 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 of?ce. in case of any inconsistency or con?ict with the short data sheet, the full data sheet shall prevail. 14.3 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 speci?cations 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 customers 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 speci?ed use without further testing or modi?cation. limiting values stress above one or more limiting values (as de?ned 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/pro? le/ter ms , 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 con?ict 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. quick reference data the quick reference data is an extract of the product data given in the limiting values and characteristics sections of this document, and as such is not complete, exhaustive or legally binding. 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 of?ce addresses, please send an email to: salesad dresses@nxp.com document status [1] [2] product status [3] de?nition objective [short] data sheet development this document contains data from the objective speci?cation for product development. preliminary [short] data sheet quali?cation this document contains data from the preliminary speci?cation. product [short] data sheet production this document contains the product speci?cation.
nxp semiconductors TEA1791T greenchip synchronous recti?er controller ? nxp b.v. 2009. all rights reserved. for more information, please visit: http://www.nxp.com for sales office addresses, please send an email to: salesaddresses@nxp.com date of release: 3 february 2009 document identifier: TEA1791T_1 please be aware that important notices concerning this document and the product(s) described herein, have been included in section legal information. 16. contents 1 general description . . . . . . . . . . . . . . . . . . . . . . 1 2 features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.1 distinctive features . . . . . . . . . . . . . . . . . . . . . . 1 2.2 green features . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.3 protection features . . . . . . . . . . . . . . . . . . . . . . 1 3 applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 ordering information . . . . . . . . . . . . . . . . . . . . . 1 5 block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 pinning information . . . . . . . . . . . . . . . . . . . . . . 2 6.1 pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6.2 pin description . . . . . . . . . . . . . . . . . . . . . . . . . 2 7 functional description . . . . . . . . . . . . . . . . . . . 3 7.1 introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7.2 start-up and undervoltage lockout (uvlo) . . 3 7.3 synchronous recti?cation . . . . . . . . . . . . . . . . . 3 7.4 supply management. . . . . . . . . . . . . . . . . . . . . 4 7.5 driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 8 limiting values. . . . . . . . . . . . . . . . . . . . . . . . . . 5 9 thermal characteristics. . . . . . . . . . . . . . . . . . . 5 10 characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 6 11 application information. . . . . . . . . . . . . . . . . . . 7 12 package outline . . . . . . . . . . . . . . . . . . . . . . . . . 8 13 revision history . . . . . . . . . . . . . . . . . . . . . . . . . 9 14 legal information. . . . . . . . . . . . . . . . . . . . . . . 10 14.1 data sheet status . . . . . . . . . . . . . . . . . . . . . . 10 14.2 de?nitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 14.3 disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 14.4 trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 15 contact information. . . . . . . . . . . . . . . . . . . . . 10 16 contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
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