TEA1721BT

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© NXP B.V. 2012. All rights reserved.

Product data sheet

Rev. 2.1 — 7 June 2012

4 of 14

NXP Semiconductors

TEA1721BT

HV start-up flyback controller with integrated MOSFET for 5 W

4.

Pinning information

4.1 Pinning

4.2 Pin description

5.

Functional description

5.1 Start-up

charging current flows from the high voltage DRAIN pin via an internal start-up current

source to the VCC pin.

Once the start level has been reached the start-up current source is switched off. During

switching operation, the start-up current source remains current-less and has zero

bleeder loss.

5.2 Primary sensing

The FB input senses the reflected secondary voltage on the primary side. The FB input

has a sample and hold function that samples the FB voltage on the secondary stroke to

control the output voltage.

operating mode.

Fig 2.

Pinning top view

TEA1721

GND1

DRAIN

GND2

GND3

SOURCE

FB

VCC

001aan294

1

2

3

4

6

5

7

Pin

Pin name

I/O type

Pin description

1

GND1

ground

2

GND2

ground

3

GND3

ground

4

FB

I

feedback input for voltage sensing

5

VCC

I

supply input

6

SOURCE

O

source for power switch

7

DRAIN

I

drain of power switch

-

-

high voltage spacer