TEA1791T/N1 - NXP - Datasheet.Directory

1. General description

The TEA1791T is a member of the new gener ation of Synchronous Rectifier (SR)

controller ICs for switched mode power supplies. Its high level of integration allows the

design of a cost-ef fective power supply with a very low number of external components.

The TEA1791T is a controller IC dedicated to 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 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 con su m pt ion

High system efficiency from no load to full load

2.3 Protection features

Undervoltage prot ect i on

3. Applications

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

TEA1791T

GreenChip synchronous rectifier controller

Rev. 02 — 7 June 2010 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

Product data sheet Rev. 02 — 7 June 2010 2 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

5. Block diagram

6. Pinning information

6.1 Pinning

6.2 Pin description

Fig 1. Block diagram

3, 5, 6, 7

n.c.

GND

SRSENSE 1

−55 mV

DRIVER

control

−12 mV−310 mV

TIMER

2 μs

2.2 μs

014aaa70

Fig 2. Pi n co nfi gura t io n

TEA1791T

SRSENSE V

GND n.c.

n.c. n.c.

DRIVER n.c.

014aaa701

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

VCC 8 supply voltage

Product data sheet Rev. 02 — 7 June 2010 3 of 12

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 (typical). When the voltage

drops below 8.0 V (typical), the under voltage 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. When 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

2μs (typical). This eliminates false switch-off due to high frequency ringing at the start of

the secondary stroke.

Because the driver output voltage is reduced when the voltage on the SRSENSE pin is

−55 mV, the exte rn al po we r switc h ca n be swit ched off quickly when the current through

the switch reache s ze ro . Th e zero current switch-off removes the need for a separate

S t andby mode to ma intain high ef ficiency during the no-load opera tion. The zero current is

detected by sensing a −12 mV level on the SRSENSE pin (see Figure 3).

Product data sheet Rev. 02 — 7 June 2010 4 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

If the secondary stroke of the flyback converter is shorter than 2 μs (typical), the dr iver

output is disabled. This will guarantee st able operation for very low du ty cycles. Whe n the

secondary stroke increases abov e 2.2 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 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 <V

startup) and underv oltage lock ou t th e dr iver out pu t

voltage is actively pulled low.

Fig 3. Synchronous rectification signals

014aaa057

0 V

−12 mV

−55 mV

−310 mV

0 A

0 V

VSRSENSE

VDRIVER

Primary

current

Secondary

current

Product data sheet Rev. 02 — 7 June 2010 5 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

8. Limiting values

[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 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 and current

ratings are valid provided the other ratings are not violated.

Symbol Parameter Conditions Min Max Unit

Voltages

VCC supply voltage continuous −0.4 +38 V

VSRSENSE voltage on pin SRSENSE continuous - 120 V

Currents

IDRIVER current on pin DRIVER duty cycle < 10 % −0.8 +3 A

ISRSENSE current on pin SRSENSE −3- mA

General

Ptot total power dissipation Tamb <80°C - 0.45 W

Tstg storage temperature −55 +150 °C

Tjjunction temperature −40 +150 °C

VESD electrostatic discharge

voltage class 2

human body

model [1] - 2000 V

machine model [2] -200V

charged device

model -500V

Table 4. 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

Product data sheet Rev. 02 — 7 June 2010 6 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

10. Characteristics

[1] The VCC stop voltage is Vstartup −Vhys.

Table 5. Chara cteristics

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

Supply voltage management (pin VCC)

Vstartup star t-up voltage 8.2 8.5 8.8 V

Vhys hysteresis voltage [1] -0.5-V

ICC(oper) operating supply current VCC =8V (V

CC <V

startup) - 0.65 - mA

under normal operation;

no load on pin DRIVER -0.95-mA

Synchronous re c tification sense input (pin SRSENSE)

Vact(drv) driver activation voltage −340 −310 −280 mV

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 1.5 2.0 2.5 μs

Long time 1.7 2.2 2.7 μs

Driver (pin DRIVER)

Isource source current VCC =15V;

voltage on pin DRIVER = 2 V −0.3 −0.25 −0.2 A

Isink sink current VCC =15V

voltage on pin DRIVER = 2 V 1 1 .4 - A

voltage on pin

DRIVER = 9.5 V 2.2 2.7 - A

Vo(max) maximum output voltage VCC =15V - 10 12 V

Product data sheet Rev. 02 — 7 June 2010 7 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

11. Application information

A switched mode power supply with the TEA1791T consists of a primary sid e

discontinuous co nduction mode flyback controller, a transformer, and an output stag e with

a feedback circuit. A MOSFET (Qsec) is used for low conduction losses in the output state.

This 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 RSRSENSE resistor should typically be 1 kΩ.

Higher values might impair correct timing, lower values may not provide sufficient

protection.

Fig 4. App lication diagram high side rectification

Fig 5. Application diagram low side rectification

Vin

PRIMARY

SIDE

CONTROLLER

Qprim VCC

GND DRIVER

TEA1791T

SRSENSE

Qsec

RSRSENSE

Vout

Cout

014aaa70

DRIVER

SRSENSE

out

GND

TEA1791T

PRIMARY

SIDE

CONTROLLER

Qsec

Cout

RSRSENSE

Qprim

014aaa8

Product data sheet Rev. 02 — 7 June 2010 8 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

12. Package outline

Fig 6. Package outline SOT96-1 (SO8)

UNIT A

max. A1A2A3bpcD

(1) E(2) (1)

ELL

pQZywv θ

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC JEITA

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

0.25 0.10.25

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

detail X

vMA

(A )

pin 1 index

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

0.010.010.041 0.004

0.039

0.016

0 2.5 5 mm

scale

O8: plastic small outline package; 8 leads; body width 3.9 mm SOT96

-1

99-12-27

03-02-18

Product data sheet Rev. 02 — 7 June 2010 9 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

13. Revision history

Table 6. Revision history

Document ID Release date Data sheet status Change notice Supersedes

TEA1791T v.2 20100607 Product data sheet - TEA1791T_1

Modifications: •Rth(j-c) added to Table 4.

•Figure 5 “Application diagram low side rectification”, added.

•Minimum value junction temperature changed in Table 3.

TEA1791T_1 20090203 Produ ct data sheet - -

Product data sheet Rev. 02 — 7 June 2010 10 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

14. Legal information

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[3] The product status of de vice(s) descr ibed in th is document m ay have cha nged since thi s document w as publish ed and may di ffe r in case of multiple devices. The latest product status

information is available on the Internet at URL http://www.nxp.com.

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Product data sheet Rev. 02 — 7 June 2010 11 of 12

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

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14.4 Trademarks

Notice: All referenced b rands, produc t names, service names and trademarks

are the property of their respective ow ners.

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

NXP Semiconductors TEA1791T

GreenChip synchronous rectifier controller

For more information, please visit: http://www.nxp.com

For sales office addresses, please send an email to: salesaddresses@nxp.com

Date of release: 7 June 2010

Document identifier: TEA1791T

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 and benefits . . . . . . . . . . . . . . . . . . . . 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 rectification . . . . . . . . . . . . . . . . . 3

7.4 Supply management. . . . . . . . . . . . . . . . . . . . . 4

7.5 Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

8 Limiting valu es. . . . . . . . . . . . . . . . . . . . . . . . . . 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 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

14.3 Disclaimers. . . . . . . . . . . . . . . . . . . . . . . . . . . 10

14.4 Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . 11

15 Contact information. . . . . . . . . . . . . . . . . . . . . 11

16 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12