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TEA1791T
GreenChip synchronous rectifier controller
Rev. 01 -- 3 February 2009 Product data sheet
1. General description
The TEA1791T 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 TEA1791T is a controller IC dedicated for synchronous rectification on the secondary side of discontinuous conduction mode and quasi-resonant flyback converters. The TEA1791T is fabricated in a Silicon On Insulator (SOI) process.
2. Features
2.1 Distinctive features
I I I I 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
I Low current consumption I High system efficiency from no load to full load
2.3 Protection features
I Undervoltage protection
3. Applications
I The TEA1791T 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 Package Name TEA1791T/N1 SO8 Description plastic small outline package; 8 leads; body width 3.9 mm Version SOT96-1 Type number
NXP Semiconductors
TEA1791T
GreenChip synchronous rectifier controller
5. Block diagram
VCC 8 SRSENSE 1 control
QR 4 TIMER 2 s 2.2 s
DRIVER
QS
-310 mV -12 mV -55 mV
3, 5, 6, 7 n.c.
2 GND
014aaa700
Fig 1.
Block diagram
6. Pinning information
6.1 Pinning
SRSENSE GND n.c. DRIVER
1 2
8 7
VCC n.c. n.c. n.c.
TEA1791T
3 4
014aaa701
6 5
Fig 2.
Pin configuration
6.2 Pin description
Table 2. Symbol SRSENSE GND n.c. DRIVER n.c n.c. n.c. VCC
TEA1791T_1
Pin description Pin 1 2 3 4 5 6 7 8 Description synchronous timing input ground not connected driver output for SR MOSFET not connected not connected not connected supply voltage
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
2 of 11
NXP Semiconductors
TEA1791T
GreenChip synchronous rectifier controller
7. Functional description
7.1 Introduction
The TEA1791T 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 (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 rectification
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 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 efficiency 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
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
3 of 11
NXP Semiconductors
TEA1791T
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 2 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 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 efficient 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 (VCC < Vstartup) and undervoltage lockout the driver output voltage is actively pulled low.
TEA1791T_1
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
4 of 11
NXP Semiconductors
TEA1791T
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 ratings are valid provided other ratings are not violated; current ratings are valid provided the other ratings are not violated. Symbol Voltages VCC VSRSENSE Currents IDRIVER ISRSENSE General Ptot Tstg Tj Vesd total power dissipation storage temperature junction temperature electrostatic discharge voltage class 2 human body model machine model charged device model
[1] [2]
[1]
Parameter supply voltage voltage on pin SRSENSE current on pin DRIVER current on pin SRSENSE
Conditions continuous continuous duty cycle < 10 %
Min -0.4 -0.8 -3
Max +38 120 +3 0.45 +150 +150 2000 200 500
Unit V V A mA W C C V V V
Tamb < 80 C
-55 -20 -
[2]
Equivalent to discharging a 100 pF capacitor through a 1.5 k series resistor. Equivalent to discharging a 200 pF capacitor through a 0.75 H coil and a 1.5 k series resistor.
9. Thermal characteristics
Table 4. Symbol Rth(j-a) Thermal characteristics Parameter thermal resistance from junction to ambient Conditions in free air Typ 150 Unit K/W
TEA1791T_1
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
5 of 11
NXP Semiconductors
TEA1791T
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 Vstartup Vhys ICC(oper) Parameter start-up voltage hysteresis voltage operating supply current VCC = 8 V (VCC < Vstartup) under normal operation; no load on pin DRIVER Synchronous rectification sense input (pin SRSENSE) Vact(drv) Vreg(drv) Vdeact(drv) td(act)(drv) tact(sr)(min) driver activation voltage driver regulation voltage driver deactivation voltage driver activation delay time minimum synchronous rectification active time Short time Long time VCC = 15 V; voltage on pin DRIVER = 2 V VCC = 15 V voltage on pin DRIVER = 2 V voltage on pin DRIVER = 9.5 V Vo(max)
[1]
[1]
Conditions
Min 8.2 -
Typ 8.5 0.5 0.65 0.95
Max 8.8 -
Unit V V mA mA
Supply voltage management (pin VCC)
-340 -65 1.5 1.7 -0.3
-310 -55 -12 125 2.0 2.2 -0.25
-280 -45 2.5 2.7 -0.2
mV mV mV ns s s A
Driver (pin DRIVER) Isource Isink source current sink current
1 2.2 -
1.4 2.7 10
12
A A V
maximum output voltage VCC = 15 V
The VCC stop voltage is Vstartup - Vhys.
TEA1791T_1
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
6 of 11
NXP Semiconductors
TEA1791T
GreenChip synchronous rectifier controller
11. Application information
A switched mode power supply with the TEA1791T consists of a primary side discontinuous conduction mode flyback 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 rectifier 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. Higher values might impair correct timing, lower values may not provide sufficient protection.
TR
Qsec
Vout Vin GND
Qprim RSRSENSE
DRIVER
Cout
PRIMARY SIDE CONTROLLER
VCC
TEA1791T
SRSENSE
014aaa702
Fig 4.
Application diagram
TEA1791T_1
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
7 of 11
NXP Semiconductors
TEA1791T
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 vMA
Z 8 5
Q A2 A1 pin 1 index Lp 1 e bp 4 wM L detail X (A 3) A
0
2.5 scale
5 mm
DIMENSIONS (inch dimensions are derived from the original mm dimensions) UNIT mm inches A max. 1.75 0.069 A1 0.25 0.10 A2 1.45 1.25 A3 0.25 0.01 bp 0.49 0.36 c 0.25 0.19 D (1) 5.0 4.8 0.20 0.19 E (2) 4.0 3.8 0.16 0.15 e 1.27 0.05 HE 6.2 5.8 L 1.05 Lp 1.0 0.4 Q 0.7 0.6 v 0.25 0.01 w 0.25 0.01 y 0.1 0.004 Z (1) 0.7 0.3 0.028 0.012
0.010 0.057 0.004 0.049
0.019 0.0100 0.014 0.0075
0.244 0.039 0.028 0.041 0.228 0.016 0.024
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. OUTLINE VERSION SOT96-1 REFERENCES IEC 076E03 JEDEC MS-012 JEITA EUROPEAN PROJECTION
ISSUE DATE 99-12-27 03-02-18
Fig 5.
TEA1791T_1
Package outline SOT96-1 (SO8)
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
8 of 11
NXP Semiconductors
TEA1791T
GreenChip synchronous rectifier controller
13. Revision history
Table 6. Revision history Release date 20090203 Data sheet status Product data sheet Change notice Supersedes Document ID TEA1791T_1
TEA1791T_1
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
9 of 11
NXP Semiconductors
TEA1791T
GreenChip synchronous rectifier controller
14. Legal information
14.1 Data sheet status
Document status[1][2] Objective [short] data sheet Preliminary [short] data sheet Product [short] data sheet
[1] [2] [3]
Product status[3] Development Qualification Production
Definition This document contains data from the objective specification for product development. This document contains data from the preliminary specification. This document contains the product specification.
Please consult the most recently issued document before initiating or completing a design. The term `short data sheet' is explained in section "Definitions". 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. 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.
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. 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.
14.3 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
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: salesaddresses@nxp.com
TEA1791T_1
(c) NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 -- 3 February 2009
10 of 11
NXP Semiconductors
TEA1791T
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . . . 8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . 9 Legal information. . . . . . . . . . . . . . . . . . . . . . . 10 Data sheet status . . . . . . . . . . . . . . . . . . . . . . 10 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Contact information. . . . . . . . . . . . . . . . . . . . . 10 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Please be aware that important notices concerning this document and the product(s) described herein, have been included in section `Legal information'.
(c) 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

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