TEA1751(L)T View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

Manufacturer

TEA1751(L)T

HV start-up DCM/QR flyback controller with integrated DCM/QR PFC controller

NXP Semiconductors. 

NXP Semiconductors

TEA1751T; TEA1751LT

GreenChip III SMPS control IC

Vsense(fb)max

(V)

0.52 V

FBSENSE peak voltage

0.13 V

PFC off

PFC on

flyback

frequency

reduction

flyback

cycle skip

mode

flyback

discontinuous

or QR

1.4 V 1.5 V 2.0 V VFBCTRL (V)

014aaa160

Fig 10. Peak current control of flyback part

The driver output is latched in the logic, preventing multiple switch-on.

7.3.4 Demagnetization (FBAUX pin)

The system is always in quasi-resonant or discontinuous conduction mode. The internal

oscillator does not start a new primary stroke until the previous secondary stroke has

ended.

Demagnetization features a cycle-by-cycle output short circuit protection by immediately

lowering the frequency (longer off-time), thereby reducing the power level.

Demagnetization recognition is suppressed during the first tsup(xfmr_ring) time (2 μs typical).

This suppression may be necessary at low output voltages and at start-up and in

applications where the transformer has a large leakage inductance.

If pin FBAUX is open circuit or not connected, a fault condition is assumed and the

converter stops operating immediately. Operation restarts as soon as the fault condition is

removed.

7.3.5 Flyback control / time-out (FBCTRL pin)

The pin FBCTRL is connected to an internal voltage source of 3.5 V via an internal

resistor (typical resistance is 3 kΩ). As soon as the voltage on this pin is above

2.5 V (typical), this connection is disabled. Above 2.5 V the pin is biased with a small

current. When the voltage on this pin rises above 4.5 V (typical), a fault is assumed and

switching is inhibited. In the TEA1751 a restart will then be made, while in the TEA1751L

the protection will be latched.

When a small capacitor is connected to this pin, a time-out function can be created to

protect against an open control loop situation. (see Figure 11 and Figure 12) The time-out

function can be disabled by connecting a resistor (100 kΩ) to ground on the FBCTRL pin.

If the pin is shorted to ground, switching of the flyback controller is inhibited.

TEA1751T_LT_2

Product data sheet

Rev. 02 — 23 December 2009

© NXP B.V. 2009. All rights reserved.

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