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TEA1761T
GreenChip synchronous rectifier controller
Rev. 02 -- 25 April 2007 Product data sheet
1. General description
The TEA1761T 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 TEA1761T is a controller IC dedicated for synchronous rectification on the secondary side of discontinuous conduction mode and quasi resonant flyback converters. Besides electronics for synchronous rectification, it also has integrated circuitry for output voltage and output current regulation. The TEA1761T is fabricated in a Silicon On Insulator (SOI) process. This NXP SOI process makes possible a wide range of operation.
2. Features
2.1 Distinctive features
I I I I I I Combined synchronous rectification and primary feedback control functionality Wide supply voltage range (8.6 V to 38 V) High level of integration, resulting in a very low external component count Wide opto coupler output voltage range (3.5 V to 38 V) Accurate internal voltage reference for voltage control (within 1 %) 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 I Internal over-temperature protection
3. Applications
The TEA1761T is intended for adapters. The device can also be used in all other discontinuous conduction mode and quasi resonant flyback systems that demand a highly efficient and cost-effective solution.
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
4. Ordering information
Table 1. Ordering information Package Name TEA1761T/N2 SO8 Description plastic small outline package; 8 leads; body width 3.9 mm Version SOT96-1 Type number
5. Block diagram
VCC 8
6
VSENSE
OPTO
5
2.5 V
7
ISENSE
OVER TEMPERATURE PROTECTION SRSENSE 1 control
50 mV
QR 4 TIMER 2 s 2.2 s
DRIVER
QS
-310 mV -12 mV -55 mV
3 n.c.
2 GND
014aaa056
Fig 1. TEA1761T block diagram
TEA1761T_2
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Product data sheet
Rev. 02 -- 25 April 2007
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NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
6. Pinning information
6.1 Pinning
SRSENSE GND n.c. DRIVER
1 2
8 7
VCC ISENSE VSENSE OPTO
TEA1761T
3 4
001aae772
6 5
Fig 2. Pin configuration for TEA1761T
6.2 Pin description
Table 2. Symbol SRSENSE GND n.c. DRIVER OPTO VSENSE ISENSE VCC Pin description Pin 1 2 3 4 5 6 7 8 Description synchronous timing input ground not connected driver output for SR MOSFET opto coupler driver output sense input for voltage control sense input for current control supply voltage
7. Functional description
The TEA1761T is the controller for synchronous rectification to be used in discontinuous conduction mode and quasi resonant flyback converters. Besides controlling the SR MOSFET, the TEA1761T contains the voltage reference and amplifiers to regulate and control the output voltage and current of the power supply.
7.1 Start-up and undervoltage lock out
The IC leaves the under-voltage lock-out state and activates the synchronous rectifier circuitry and also the voltage/current sense circuitry as soon as the voltage on the VCC pin is above 8.6 V (typical). As soon as the voltage drops below 8.1 V (typical), the under-voltage lock-out state is re-entered and the SR driver output is actively kept low and also the opto driver output is disabled.
7.2 Synchronous rectification
After a negative voltage (-310 mV typical) is sensed on the SRSENSE pin, the driver output voltage is made 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
TEA1761T_2 (c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
3 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
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 (typical). This will eliminate 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 fast 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 no-load operation. The zero current is detected by sensing a -12 mV level on the SRSENSE pin. See Figure 3.
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 (typical), the driver output is disabled. This will guarantee stable operation for very low duty cycles. When the secondary stroke increases above 2.2 s (typical) then the driver output is again enabled.
7.3 SMPS output voltage and current regulation
The output voltage of the flyback Switched Mode Power Supply (SMPS) can be controlled by sensing the output voltage via pin VSENSE. The feedback loop via the primary controller can regulate the output voltage of the switched mode power supply by regulating the voltage on pin VSENSE, to 2.5 V. Also the output current of the flyback SMPS can be controlled or limited. The voltage on pin ISENSE is regulated or limited to 50 mV above the voltage on pin GND.
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
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NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
7.4 Opto output
The opto output is intended to drive an opto coupler (see Figure 5). The opto output has an open-drain output configuration. The maximum sink current is internally limited to 5 mA (typical). The output is linearly controlled via the VSENSE and ISENSE input pins. An over-temperature situation will switch the opto output to its maximum sink current. During start-up (VCC < Vstartup) and undervoltage lock-out the output is disabled.
7.5 Supply management
All (internal) reference voltages are derived from a temperature compensated, on-chip band gap circuit. The reference voltage is trimmed to an accuracy within 1 %.
7.6 OverTemperature Protection (OTP)
The IC provides an accurate internal overtemperature protection of 150 C (typical). The IC will maximize the current of pin OPTO as soon as the internal temperature limit is reached. The opto signal can be used on the primary side of the flyback controller to activate the SMPS protection or limit the output power. As soon as the overtemperature condition is solved, normal operation will resume.
7.7 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 lock-out the driver output voltage is actively pulled low.
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
5 of 13
NXP Semiconductors
TEA1761T
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 VOPTO VSRSENSE VVSENSE VISENSE Currents IOPTO IDRIVER ISRSENSE General Ptot Tstg Tj ESD VESD electrostatic discharge voltage class 2 human body model machine model charged device model
[1] [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 10 resistor.
[1] [2]
Parameter supply voltage voltage on pin OPTO voltage on pin SRSENSE voltage on pin VSENSE voltage on pin ISENSE current on pin OPTO current on pin DRIVER current on pin SRSENSE total power dissipation storage temperature junction temperature
Conditions continuous continuous continuous continuous
Min -0.4 -0.4 -0.4 -0.4 -
Max +38 +38 120 +5 +5 12 +3 0.45 +150 +150
Unit V V V V V mA A mA W C C
duty cycle < 10 %
-0.8 -3
Tamb < 80 C
-55 -20
-
2000 200 500
V V V
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
The graph in Figure 4 shows the relationship between junction temperature and VSENSE voltage.
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
6 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
2600 regulated VSENSE voltage (mV) 2520
001aae779
2480
2440
2400 -50
0
50
100 150 junction temperature (C)
Fig 4. Typical regulated VSENSE voltage versus junction temperature
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) maximum output voltage VCC = 15 V 1 2.2 1.4 2.7 10 12 A A V 1.5 1.7 -0.3 -340 -65 -310 -55 -12 125 2 2.2 2.5 2.7 -280 -45 mV mV mV ns s s A
[1]
Conditions
Min 8.35 -
Typ 8.6 0.5 1 1.4
Max 8.85 -
Unit V V mA mA
Supply voltage management (pin VCC)
Driver (pin DRIVER) Isource Isink source current sink current -0.25 -0.2
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
7 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
Table 5. Characteristics ...continued 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 IO(max) VO(min) Vreg(VSENSE) II(VSENSE) gm GB Vreg(ISENSE) II(reg)(ISENSE) gm GB Tpl(max) Tpl(hys) Parameter Conditions Min 4 Typ 5 Max 12 3.5 Unit mA V Opto output (pin OPTO) maximum output current VOPTO > 5 V minimum output voltage IOPTO = 4 mA
Voltage sense (pin VSENSE) regulation voltage on pin See Figure 4 VSENSE input current on pin VSENSE transconductance gain bandwidth product regulation voltage on pin ISENSE regulation input current on pin ISENSE transconductance gain bandwidth product maximum protection level temperature protection level hysteresis temperature VISENSE = Vreg(ISENSE) VISENSE to IOPTO RL = 1 k VVSENSE = Vreg(VSENSE) VVSENSE to IOPTO RL = 1 k 2.475 2.5 -100 1 46 -200 1 140 50 -100 15 150 12 54 0 0 40 2.525 V +100 nA A/V MHz mV nA A/V MHz C C
Current sense (pin ISENSE)
Temperature protection
[1]
The VCC stop voltage is Vstartup - Vhys.
11. Application information
A switched mode power supply with the TEA1761T 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 TEA1761T. The output voltage and/or current is also controlled by the TEA1761T via the opto coupler connection to the primary side. See Figure 5. The output voltage is set by resistors Rfb1 and Rfb2. The output current is controlled by the resistor Risense. 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 TEA1761T from excessive voltages. The SRSENSE resistor should typically be 1 k. Higher values might impair correct timing, lower values may not provide sufficient protection.
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
8 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
Vout
Ropto
OPTO
TR
Rfb1
Vin
Cfb
VCC OPTO VSENSE
Cout
Rsrsense Qprim Qsec
SRSENSE
TEA1761T
Rfb2
PRIMARY SIDE CONTROLLER
DRIVER GND
Risense
ISENSE
001aae775
Fig 5. Application example TEA1761T
12. Test information
12.1 Quality information
The General Quality Specification for Integrated Circuits, SNW-FQ-611 is applicable.
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
9 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
13. 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 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 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
ISSUE DATE 99-12-27 03-02-18
Fig 6. Package outline SOT96-1 (SO8)
TEA1761T_2 (c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
10 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
14. Revision history
Table 6. Revision history Release date 20070425 Data sheet status Product data sheet Change notice Supersedes TEA1761T_1 Document ID TEA1761T_2 Modifications:
* * * * * *
Updated limiting values for VSRSENSE in Table 3. Updated characteristic values for Isource and Isink in Table 5. Added footnote [1] to Table 5. Soldering section removed. The format of this data sheet has been redesigned to comply with the new identity guidelines of NXP Semiconductors. Legal texts have been adapted to the new company name where appropriate. Objective data sheet -
TEA1761T_1
20060331
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
11 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
15. Legal information
15.1 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.
15.2 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.
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.
15.3 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 a NXP Semiconductors product can reasonably be expected to
15.4 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.
16. Contact information
For additional information, please visit: http://www.nxp.com For sales office addresses, send an email to: salesaddresses@nxp.com
TEA1761T_2
(c) NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 02 -- 25 April 2007
12 of 13
NXP Semiconductors
TEA1761T
GreenChip synchronous rectifier controller
17. 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 7.6 7.7 8 9 10 11 12 12.1 13 14 15 15.1 15.2 15.3 15.4 16 17 General description . . . . . . . . . . . . . . . . . . . . . . 1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Distinctive features . . . . . . . . . . . . . . . . . . . . . . 1 Green features . . . . . . . . . . . . . . . . . . . . . . . . . 1 Protection features . . . . . . . . . . . . . . . . . . . . . . 1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Ordering information . . . . . . . . . . . . . . . . . . . . . 2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Pinning information . . . . . . . . . . . . . . . . . . . . . . 3 Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . 3 Functional description . . . . . . . . . . . . . . . . . . . 3 Start-up and undervoltage lock out. . . . . . . . . . 3 Synchronous rectification . . . . . . . . . . . . . . . . . 3 SMPS output voltage and current regulation . . 4 Opto output . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Supply management. . . . . . . . . . . . . . . . . . . . . 5 OverTemperature Protection (OTP) . . . . . . . . . 5 Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Limiting values. . . . . . . . . . . . . . . . . . . . . . . . . . 6 Thermal characteristics. . . . . . . . . . . . . . . . . . . 6 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Application information. . . . . . . . . . . . . . . . . . . 8 Test information . . . . . . . . . . . . . . . . . . . . . . . . . 9 Quality information . . . . . . . . . . . . . . . . . . . . . . 9 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'.
(c) NXP B.V. 2007.
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: 25 April 2007 Document identifier: TEA1761T_2

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