TEA1751LT/N1 NXP Semiconductors, TEA1751LT/N1 Datasheet - Page 15

• Manufacturer Part Number: TEA1751LT/N1
• Description: AC-DC, PFC, FLYBACK, CNTRL, 16SOIC
• Manufacturer: NXP Semiconductors

Specifications of TEA1751LT/N1

• Input Voltage: 276V
• Output Current: 1.2A
• Output Voltage: 11V
• No. Of Outputs: 2
• Power Dissipation Pd: 600mW
• Voltage Regulator Case Style: SOIC
• No. Of Pins: 16
• Operating Temperature Range: -40°C To
• Supply Voltage Range: 21V To 23V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

NXP Semiconductors
TEA1751T_LT_2
Product data sheet
7.3.4 Demagnetization (FBAUX pin)
7.3.5 Flyback control / time-out (FBCTRL pin)
The driver output is latched in the logic, preventing multiple switch-on.
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 t
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.
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
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.
Fig 10. Peak current control of flyback part
FBSENSE peak voltage
Rev. 02 — 23 December 2009
V
sense(fb)max
(V)
0.52 V
0.13 V
cycle skip
flyback
mode
PFC off
TEA1751T; TEA1751LT
frequency
reduction
flyback
1.4 V
1.5 V
Figure 11
PFC on
2.0 V
discontinuous
GreenChip III SMPS control IC
sup(xfmr_ring)
flyback
or QR
V
and
FBCTRL
Figure
(V)
014aaa160
time (2 μs typical).
© NXP B.V. 2009. All rights reserved.
12) The time-out
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