NXP Semiconductors TEA1995T DATA SHEET

TEA1995T

GreenChip dual synchronous rectifier controller

Rev. 3 — 5 December 2017 Product data sheet

1 General description

The TEA1995T is the first product of a new generation of Synchronous Rectifier (SR)
controller ICs for switched mode power supplies. It incorporates an adaptive gate drive
method for maximum efficiency at any load.

The TEA1995T is a dedicated controller IC for synchronous rectification on the
secondary side of resonant converters. It has two driver stages for driving the SR
MOSFETs, which rectify the outputs of the central tap secondary transformer windings.
The two gate driver stages have their own sensing inputs and operate independently.

The TEA1995T can also be used in multi-output flyback converters with the SR MOSFET
placed at the low side.

The TEA1995T is fabricated in a Silicon-On-Insulator (SOI) process.

2 Features and benefits

2.1 Efficiency features

• Adaptive gate drive for maximum efficiency at any load

• Supply current in energy save operation below 200 μA

2.2 Application features

• Wide supply voltage range from 4.5 V to 38 V

• Dual synchronous rectification for LLC resonant in SO8 package

• Synchronous rectification for multi-output flyback converters

• Supports 5 V operation with logic level SR MOSFETs

• Differential inputs for sensing the drain and source voltages of each SR MOSFET

2.3 Control features

• SR control without minimum on-time

• Adaptive gate drive for fast turn-off at the end of conduction

• UnderVoltage LockOut (UVLO) protection with active gate pull-down

NXP Semiconductors

GreenChip dual synchronous rectifier controller

TEA1995T

3 Applications

The TEA1995T is intended for resonant power supplies. In such applications, it can drive
two external synchronous rectifier MOSFETs for the rectification of the voltages on the
two secondary windings of the transformer. These MOSFETs replace diodes. It can be
used in all power supplies requiring high efficiency:

• Adapters

• Power supplies for desktop PC and all-in-one PC

• Power supplies for television

• Power supplies for servers

4 Ordering information

Table 1. Ordering information

Type number Package

Name Description Version

TEA1995T/1 SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1

5 Marking

Table 2. Marking

Type number Marking code

TEA1995T/1 TEA1995

TEA1995T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.

Product data sheet Rev. 3 — 5 December 2017

2 / 18

NXP Semiconductors

aaa-016986

V AND I

REFERENCE

5 V

REGULATOR

DRIVER
SUPPLY

11 V

enable

UNDER
VOLTAGE
LOCKOUT

ENERGY SAVE

CONTROL

TURN ON

off regulation

on regulation

turn-on

DSA

SSA

DSB

SSB

GDA

VCC

SWITCH OFF

+150 mV-50 mV-55 mV-400 mV

LOGICIC

TURN ON

off regulation

on regulation

turn-on

GDB

GND

SWITCH OFF

+150 mV-50 mV-55 mV-400 mV

6 Block diagram

TEA1995T

GreenChip dual synchronous rectifier controller

Figure 1. TEA1995T block diagram

TEA1995T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.

Product data sheet Rev. 3 — 5 December 2017

3 / 18

NXP Semiconductors

IC

GDB GDA

GND V

CC

DSB DSA

SSB SSA

aaa-016990

1

2

3

4

6

5

8

7

7 Pinning information

7.1 Pinning

Figure 2. TEA1995T pin configuration

7.2 Pin description

Table 3. Pin description

Symbol Pin Description

GDB 1 gate drive output MOSFET B

GND 2 ground

DSB 3 drain sense input for synchronous timing MOSFET B

SSB 4 source sense input MOSFET B

SSA 5 source sense input MOSFET A

DSA 6 drain sense input for synchronous timing MOSFET A

V

CC

GDA 8 gate drive output MOSFET A

TEA1995T

GreenChip dual synchronous rectifier controller

7 supply voltage

TEA1995T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.

Product data sheet Rev. 3 — 5 December 2017

4 / 18

NXP Semiconductors

aaa-016991

DSA

GDA

SSA

DSB

V

CC

GDB

SSB

GND

Q

prim1

C

HB

Q

prim2

Q

sec1

PRIMARY

SIDE

CONTROLLER

IC

V

in

V

out

TR

IC1

Q

sec2

C

out

8 Functional description

8.1 Introduction

The TEA1995T is a controller IC for synchronous rectification. It is perfectly suited to
be used in resonant applications. It can drive two synchronous rectifier MOSFETs on
the secondary side of the central tap transformer winding. Figure 3 shows a typical
configuration.

TEA1995T

GreenChip dual synchronous rectifier controller

Figure 3. TEA1995T typical configuration

8.2 Start-up and undervoltage lockout (VCC pin)

When the voltage on the VCC pin exceeds V
activates the SR circuitry. When the voltage drops to below V
UVLO state. The SR MOSFET gate driver outputs are actively kept low. For proper
operation, the VCC pin must be decoupled with an extra capacitor (not only with C
between the VCC pin and the GND pin. To reduce inductance effects because of high
gate driver currents, the extra capacitor must be connected as close as possible to the
IC.

start

8.3 Drain sense (DSA and DSB pins)

The drain sense pins are input pins capable of handling input voltages up to 100 V.
At positive drain sense voltages, the gate driver is in off-mode with pulled-down gate
driver pins (pins GDA or GDB). At negative drain sense voltages, the IC enables the SR
through sensing the drain source differential voltage.

, the IC leaves the UVLO state and

, the IC reenters the

stop

out

)

TEA1995T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.

Product data sheet Rev. 3 — 5 December 2017

5 / 18

NXP Semiconductors

8.4 Synchronous Rectification (SR; DSA, SSA, DSB, and SSB pins)

The IC senses the voltage difference between the drain sense (pins DSA and DSB) and
the source sense (pins SSA and SSB) connections. The drain source differential voltage
of the SR MOSFET is used to drive the gate of the SR MOSFET.

TEA1995T

GreenChip dual synchronous rectifier controller

When this absolute voltage difference is higher than V

, the corresponding gate

act(drv)

driver output turns on the external SR MOSFET. When the external SR MOSFET is
switched on, the absolute voltage difference between the drain and the source sense
connections drops to below V

. The regulation phase follows the turn-on phase.

act(drv)

In the regulation phase, the IC regulates the difference between the drain and the source
sense inputs to an absolute level (V
V
until the V

, the gate driver output increases the gate voltage of the external SR MOSFET

reg(drv)

level is reached. The SR MOSFET does not switch off at low currents.

reg(drv)

). When the absolute difference is higher than

reg(drv)

The IC operates without minimum on-time.

When the absolute difference is lower than V

deact(drv)

, the gate driver output decreases
the gate voltage of the external SR MOSFET. The voltage waveform on the gate of the
SR MOSFET follows the waveform of the current through the SR MOSFET. When the
current through the external SR MOSFET reaches zero, the SR MOSFET is quickly
switched off.

After the SR MOSFET switch-off, the drain voltage increases. For a drain voltage above
V

, a low ohmic gate pull-down of R

swoff

keeps the gate of the SR MOSFET switched

pd(G)

off.

TEA1995T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.

Product data sheet Rev. 3 — 5 December 2017

6 / 18